AN ABSTRACT OF THE THESIS OF
Bruce Carl Mundy
for the degree of
Master of Science
in the School of Oceanography presented on
Title:
7 June 1983
Yearly Variation in the Abundance and Distribution of Fish
Larvae in the Coastal Zone off Yaguina Head, Oregon, from June 1969 to
August 1972
Abstract approved:
Redacted for privacy
r. S. L. Richardson
Larval fishes in waters 2-18 km off Yaquina Head, Oregon during
1969-1972 were most abundant in February and May or June of each year.
Few larvae were found in August and September.
The two peaks in
abundance were composed of two species-groups.
The winter group,
composed primarily of Ammodytes hexapterus, Ophiodon elongatus,
Hemilepidotus hemilepidotus, H. spinosus and Chirolophis spp., oc-
curred from January through April.
A separate species-group, composed
of Parophrys vetulus and Sebastes spp. (October through early July),
was also most abundant in winter months.
The spring-summer group,
which occurred from February through August, consisted of three
subgroups: 1.) the Osmeridae, Microgadus proximus, Isopsetta isolepis,
Psettichthys melanostictus and three Artedius species (abundant from
February through August), 2.) Enophrys bison and Platichthys stellatus
(February through August), 3.,) Clinocottus acuticeps, Cottus asper and
Lyopsetta exilis (March through August).
Larvae of the winter group appeared after the onset of winter
storms in each year.
spring.
They became rare when upwelling began in the
Members of this group were most abundant in the winter of
1969-70.
Calm weather, reduced storm frequency, sea surface
temperatures 1-2°C above those in other years and high abundances
of copepod nauplii were related to high annual abundances of
species in the winter group.
Larvae of the spring-summer groups appeared after northerly
winds prevailed in the spring.
Predation and cessation of spawning
may have been related to the disappearance of larvae in August.
Three of the most dominant taxa in these groups were most abundant
in 1970-71.
Variable winds in late winter, calm conditions in
early spring and weak upwelling were related to high abundances of
those species (Osmeridae, Isopsetta isolepis, and Microgadus
proximus).
Psettichthys melanostictus and Artedius meanyi larvae
differed from other members of the spring-summer groups by being
most abundant when upwelling was strong and persistent.
Parophrys vetulus larvae appeared after onshore convergence
began in autumn.
Reduced storm frequency, warm winter water
temperatures and variable winds were related to high abundances of
Parophrys larvae.
Year-class success, determined from commercial
catches, was highest in years when larvae were abundant in autumn.
Abundances of P. vetulus and Isopsetta isolepis larvae were not
good predictors of year-class strengths in the fishery.
Mortality
of pelagic larvae, prior to transformation, was not the only
determinant of year-class strength in those species.
Yearly Variation in the Abundance and Distribution
of Fish Larvae in the Coastal Zone off
Yaquina Head, Oregon, From June 1969 to August 1972
by
Bruce Carl Mundy
A THESIS
submitted to
Oregon State University
in partial fulfillment of
the requirements for the
degree of
Master of Science
Completed 7 June 1983
Commencement June 1984
APPROVED:
Redacted for privacy
essor oqceanograp
n cnarge
or
Redacted for privacy
Redacted for privacy
an or the bra
Date thesis is presented
Typed by Karen Dykes and
Deborah Grossman for
7 June 1983
Bruce Carl Mundy
ACKNOWL EDGEMENTS
Dr. Sally L. Richardson, my major professor, deserves primary
recognition for her guidance throughout my research.
The growth of
my understanding of larval fish ecology, taxonomy and general
ichthyology is due to her efforts and abilities.
I am grateful for
her patience while I strayed from oceanography to freshwater larval
fish research and back.
I thank my committee members, Drs. William Pearcy, George
Boehiert, Carl Bond, and Howard Wilson, for their help in
preparation of this thesis.
Dr. Pearcy's incisive editing, based
on his profound knowledge of North Pacific ecosystems and fisheries
oceanography, added immeasurably to the quality of this study.
Dr.
Boehiert contributed not only by his editing, but by unifying many
concepts of larval fish ecology for me during his courses and in
numerous discussions.
Dr. Bond has enriched my ichthyologic
education with his knowledge of geographic ecology and of the
western North American ichthyofauna, both marine and freshwater.
My study would not have been possible without the efforts of
the initiators of the Sea Grant Early Life History and Pleuronectid
Projects, as well as those who collected and sorted the samples.
Dr. Richardson and Sharon Myers Roe initially identified the fish
larvae.
Dr. Charles Miller (OSU Oceanography), William Gilbert
(OSU Oceanography), Dr. William Peterson (State Univ. New York,
Stonybrook), Robert Demory (Ore. Dept. Fisheries and Wildlife) and
Andrew Bakun (National Marine Fisheries Service, Monterey) provided
unpublished data.
Dr. Michael Richardson (Office of Naval
Research, Biloxi, Miss.), Dr. David Thomas (OSU Statistics) and
Steven Shiboski (OSU Statistics) advised me about data analysis.
Deborah Grossman carefully typed my final thesis draft under the
stress of impending deadlines and constant editorial changes.
My education in oceanography and ichthyology has been enriched
by many discussions with colleagues.
Dena Gadomski not only
discussed her studies of larval fish feeding with me, but was
responsible for inciting me to overcome inertia and finish this
thesis.
Waldo Wakefield, Dr. Joanne Laroche, Dr. Wendy Gabriel and
Wayne Laroche shared their knowledge of ichthyology and larval fish
ecology during many pleasant hours of work in Corvallis.
Dr. David
Stein has greatly increased my understanding of systematics and
deep-sea biology, and has alway been an excellent example of a
dedicated ichthyologist.
Betsy Washington, Dr. Barbara Sullivan,
Larry LaBolle and Kevin Howe also have my gratitude for their
willingness to discuss things aquatic.
Dr. Herbert Austin (VIMS)
first introduced me to ichthyoplankton research.
Drs. Carl Shreck
and Hiram Li supported my in my digression into freshwater
ichthyoplanktology, but always encouraged me to finish this thesis.
Many other friends have helped me during this time.
My
parents and family have tolerated my fishy obsessions for many
years.
Lyn Gilman, Jim and Julie Gish, Wayne Youngquist, Mike
Kravitz, Joan Flynn, Jim Long, Barb Dexter, John Dickinson, Ken
Tighe, Harvey Siebert, Randy Hjort, Pat Hulet, Mary Yoklavich,
Chris Wilson, John Shenker, Marilyn Gum
and Ric Brodeur have all
made my time working on this happy and interesting.
I have learned from all and count all as friends.
TABLE OF CONTENTS
INTRODUCTION
Previous Studies of Ichthyoplankton Off the
Oregon Coast
The Relationship of Environmental Factors to
Larval Fish Ab' indance
Coastal Hydrography Off Oregon
Biotic Consequences of Coastal Currents Off
Oregon
MATERIALS AND METHODS
Field Sampling
Laboratory Procedures
Additional Data
Dominance and Classification Analysis
RESULTS
2
5
8
11
14
14
15
16
18
22
Sampling Gear Efficiency
Overall Species Composition and Dominant Species
The Annual Cycle of Larval Fish Abundance in
Oregon Coastal Waters
Annual Variations in Larval Fish Occurrences,
1969-1972
The Annual Cycle of Larval Fish Species-Group
Occurrences in Coastal Waters Off Oregon
Annual Variation in the Relative Dominance
(Biological Index) and Abundance (#/102)
of Dominant Taxa
Annual Variability in the Abundance (#/10m2) and
Size Composition of the Dominant Taxa
Osmeridae (smelts)
Parophrys vetulus (English sole)
Isopsetta isolepis (butter sole)
Psettichthys melanostictus (sand sole)
Microgadus proximus (Pacific tomcod)
Sebastes spp. (rockfishes)
Artedius harringtoni (scalyhead sculpin)
Ammodytes hexapterus (Pacific sand lance)
Platichthys stellatus (starry flounder)
Lyopsetta exilis (slender sole)
Artedius meanyi (Puget Sound sculpin)
Artedius fenestralis (padded sculpin)
Cyclopteridae Type I (snailfishes)
Spatial Distribution of the Dominant Taxa
Weather Conditions from June 1969 through August
1972
22
23
24
25
29
30
31
31
33
34
35
36
37
38
39
39
40
40
41
42
42
TABLE OF CONTENTS (continued)
Wind Speed and Direction
Upwelling Indices
Surface Water Temperatures
Surface Salinities
Bottom Salinities
DISCUSSION
Comparisons with Previous Studies of Larval
Fish Assemblages Off Oregon
The Relationship of Environmental Factors to
Annual Differences in Occurrences of Taxa
in the Winter Species-Groups
Parophrys vetulus (English sole)
Sebastes spp. (rockfishes)
Ammodytes hexapterus (Pacific sand lance)
The Relationship of Environmental Factors to
Annual Differences in Occurrences of Taxa
in the Spring and Summer Species-Groups
Osmeridae (smelts)
Isopsetta isolepis (butter sole)
Psettichthys melanostictus (sand sole)
Microgadus proximus (Pacific tomcod)
Artedius harringtoni (scalyhead sculpin)
Platichthys stellatus (starry flounder)
Lyopsetta exilis (slender sole)
Artedius meanyi (Puget Sound sculpin)
Artedius fenestralis (padded sculpin) and
Cyclopteridae Type I (snailfishes)
Comparisons of the Annual Variability in
Occurrences of Larval Fish Off Oregon to
That in Other Groups of Zooplankton
Spawning Seasons, Transport Mechanisms and
Early Life Histories of Coastal
Eastern North Pacific Fishes
LITERATURE CITED
44
46
48
49
51
53
53
54
56
61
62
63
69
71
72
74
75
76
76
77
78
78
81
8-2
TABLES
106
FIGURES
120
APPENDICES
151
7
LIST OF FIGURES
Figure
2
3
4
5
6
7
8
9
10
11
12
Page
Location of Stations Sampled: Stations
Designated With Open Circles Were Sampled From
22 June - 20 October 1970. Stations Designated
With Solid Circles Were Sampled From 4 November
1970 - 5 August 1972.
120
Mean Standardized Abundance Of All Taxa [E (No.
Larvae/lU m2)/No. Stations Sampled] At All
Stations Sampled On Each Date In 1969-70
121
Mean Standardized Abundance Of All Taxa [E (No.
Larvae/1O m2)/No. Stations Sampled] At All
Stations Sampled On Each Date In 1970-71
122
Mean Standardized Abundance Of All Taxa [
(No.
Larvae/1O rn2)/No. Stations Sampled] At All
Stations Sampled On Each Date In 1971-72
123
a) Time-Groups From the Classification Analysis
Using Data From 1969-70, Excluding Osmerids,
Sebastes and Cyclopterids. b) Species-Groups
From the Classification Analysis Using Data
From 1969-70, Excluding Osmerids, Sebastes and
Cyclopterids
124
Time-Groups and Species-Groups From the
Classification Analysis Using Data From 1970-71,
Excluding the Osmerids, Sebastes, and Cyclopterids
126
Time-Groups and Species-Groups From the
Classification Analysis Using Data From 19711972, Excluding the Osmerids, Sebastes and
Cyclopterids
127
Monthly Standardized Length Frequencies of
Osmeridae
128
Monthly Standardized Length Frequencies of
Parophrys vetulus
132
Monthly Standardized Length Frequencies of
Isopsetta isolepis
134
Monthly Standardized Length Frequencies of
Psettichthys melanostictus
135
Monthly Standardized Length Frequencies of
Microgadus proximus
136
LIST OF FIGURES (CONTINUED)
Figure
13
14
15
16
17
18
19
20
21
22
23
24
Page
Monthly Standardized Length Frequencies of
Sebastes spp.
137
Monthly Standardized Length Frequencies of
Artedius harringtoni
138
Monthly Standardized Length Frequencies of
Ammodytes hexapterus
139
Monthly Standardized Length Frequencies of
Platichthys stellatus
140
Monthly Standardized Length Frequencies of
Lyopsetta exilis
141
Monthly Standardized Length Frequencies of
Artedius meanyi
142
Monthly Standardized Length Frequencies of
Artedius fenestralis
143
Monthly Standardized Length Frequencies of
Cyclopteridae Type I
144
a) Progressive Wind Vector Diagrams For 16 April
1969 - 31 Dec. 1970. (Peterson and Miller, 1975)
b) Progressive Wind Vector Diagram For 1 Jan. 31 Dec. 1971. (From Peterson and Miller, 1975)
c) Progressive Wind Vector Diagram Eon Jan. 31 Dec. 1972.
(From Peterson and Miller, 1975)
145
Weekly Mean Values of the Coastal Divergence
Index (= Bakun's Upwelling Index) at 45° N
125° W (From Bakun, 1975)
148
Monthly Mean Estimates of Wind Stress Curl
(Nelson's Offshore Divergence Index) For 19691972 At 45°N 125°W (Unpublished Data From A.
Bakun, NMFS)
149
Relative Year-Class Strength Estimates For
Butter Sole (Isopsetta isolepis) and
English Sole (Parophrys vetulus)
150
LIST OF TABLES
Table
I
II
Page
Two-way Coincidence Tables for Individual Years
(Sept.- August), Excluding Multispecies Taxa.
(All time and species-groups form at a BrayCurtis Dissimilarity Value of 0.5)
106
Taxonomic Composition and Times of Occurrence
of Each Species-Group in
a) 1969-70, b) 1970-71,
and c) 1971-72
107
Summary of Kruskal-Wallis Tests for Differences
in Abundance of Larvae Between Years
109
Modified Eager's Biological Indices of Dominance
(Richardson, 1973) for the Thirteen Most Abundant
Taxa in each of the Three Years
110
:
III
IV
V
Days per Month with Winds Greater than 15 knots.
(*greater than 20 kts) Number of Days of
Storms per Month (Winds > 15 kts; Precipitation
1.0 cm)
VI
VII
VIII
IX
Average Monthly Precipitation (cm).
Number of
Days with Precipitation Greater than 1.0 cm in
Each Month
APPENDIX
I
112
Dates on Which Major Storms Occurred, 1969-1972.
Storms: From wind and precipitation data (wind
15 knots, rain > 0.4 inches, *winds > 20
knots)
113
Surface Temperatures (°C) at each Station on
each Sampling Date
114
Surface Salinity (°/oo) at Each Station on Each
Samping Date (Columbia River Plume Water
32.5
X
111
/oo)
116
Bottom salinities (°/oo) at each station on
each sampling date when measurements were taken
118
Taxa taken in this study, with references
containing descriptions, illustrations or
photographs of larvae.
151
LIST OF TABLES (CONTINUED)
Table
APPENDIX
II
APPENDIX
III
Page
Species taken, number of specimens of each
species, number of sample dates on which each
species was taken, total standardized abundance
(E number/lO m2 of sea surface) of each species,
percent of total catch of each species, percent
of standardized abundance of each species, and
biological index for each species.
154
Total Standardized Abundances of all Species
at each Station for each date.
157
YEARLY VARIATION IN THE ABUNDANCE AND DISTRIBUTION OF FISH LARVAE
IN THE COASTAL ZONE OFF YAQUINA HEAD, OREGON, FROM JUNE 1969 TO
AUGUST 1972
INTRODUCTION
The survival of fish in their larval stage has been considered
to be closely linked to variations in year-class strengths
(Gulland, 1965; Hempel, 1965; May, 1974; Gushing, 1975; Lasker,
1981b).
Hjort (1914, 1926) first suggested that a "critical
period", a time of high mortality due to starvation, during "the
very earliest larval and young fry stages" was the time of
year-class strength formation.
The existence of this critical
period has not yet been well corroborated, but mortality during the
larval stage has been widely accepted as a cause of annual
differences in fish abundance (May, 1974).
The critical period is
usually assumed to be a short period at the onset of exogenous
feeding (May, 1974), but Gulland (1965) suggested that alternative
critical phases, possibly of longer duration, may occur later in
the early life history stages of fish.
An alternative critical
phase may occur for demersal fish species during their
transformation from planktonic larvae to demersal juveniles (Steele
and Edwards, 1970; Marliave, 1977), and variations in survival of
late larval and juvenile Engraulis mordax (northern anchovy) may
determine recruitment during some years (Hewitt and Methot, 1982).
However, studies of larval abundance have been considered necessary
2
for understanding recruitment processes in marine fishes (Hempel,
1974; Hunter, 1976).
This study is an analysis of ichthyoplankton samples collected
from June 1969 to August 1972 along a transect offshore of Yaquina
Head, Oregon.
It is the first attempt to relate annual variations
in the abundance of fish larvae from the Oregon upwelling zone to
fluctuations in environmental factors on a year-round basis.
The
objectives of this study are:
1) To describe the seasonal and yearly variations in the
occurrence and abundance of fish larvae in the Oregon coastal zone.
2) To relate seasonal and yearly variations in the abundance
of numerically dominant species to variations in hydrographic
conditions, weather patterns and biological conditions that were
measured during the time of ichthyoplankton sampling.
3) To examine the annual variation in the abundance of
Parophrys vetulus (English sole) larvae with respect to resulting
year-class strengths, and to relate the results of this study to
those of other studies of factors influencing recruitment of that
species.
Previous Studies of Ichthyoplankton Off the Oregon Coast
Ichthyoplankton sampling off Oregon began in the middle of
this century, when Aron (1958, 1959, 1960) collected micronekton
beyond the continental shelf.
Other early surveys of plankton and
micronekton included ichthyoplankton taxa in their lists of catch
composition (Pearcy, 1962b, LeBrasseur, 1964, 1970).
Waidron
3
(1972) compared the distribution of larval fish during April and
May 1967 off Washington and Oregon out to 550 km to their distribution in Puget Sound, emphasizing the Scorpaenidae,
Pleuronectidae, Gadidae, Myctophidae and Ammodytidae.
Richardson
(1973) discussed the species composition and distribution of
dominant families of ichthyoplankton taken from May through October
1969.
Pearcy and Myers (1974) studied the annual variation of fish
larvae in Yaquina Bay over eleven years (1960-1970), and briefly
compared the abundance of larvae in the ocean at the mouth of the
bay to that in the bay during one year.
Laroche (1976) reported on
the seasonal abundance and species composition of larvae 5.5 km
offshore of the Columbia River mouth during 1975, emphasizing the
Osmeridae. The early life histories and larval distributions of
Eopsetta jordani (petrale sole), Glyptocephalus zachirus (rex
sole), and Microstomus pacificus (Dover sole) were discussed by
Pearcy et al. (1977).
Misitano (1977) studied the utilization of
the Columbia River estuary as a spawning and nursery area for
euryhaline fishes in 1973 by conducting an ichthyoplankton survey.
Richardson (1981) found that Engraulis mordax spawning is
associated with the Columbia River plume off Oregon during June to
August, and estimated the spawning biomass of the northern
subpopulation of that species from ichthyoplankton surveys in 1975
and 1976.
Techniques of counting daily otolith growth increments
have been used to estimate larval growth rates of Engraulis mordax
and northern lampfish, Stenobrachius leucopsarus (Methot, 1981), as
well as Parophrys vetulus (Laroche et al., 1982; Rosenberg and
Laroche, 1982) off Oregon.
Kendall and Clark (1982a,b) reported on
larval fish distributions off Washington, Oregon and northern
California, 5.6-370.0 km from shore, identifying recurrent fauna]
groups in the region.
Three published studies, and two associated data reports, have
discussed annual variations in the abundance of ichthyoplankton off
Oregon.
Richardson and Pearcy (1977) identified a coastal
assemblage (2-28 km offshore) and an offshore assemblage (37-111
km) of larvae, and described changes in larval abundance in each
group from January 1971 to August 1972.
They discussed the role of
currents and fronts in maintaining the distributional patterns, but
did not speculate on environmental factors related to annual
differences in larval abundance.
In data reports from that study,
Richardson and Stephenson (1978) used portions of the total data
set (Richardson, 1977) for numerical classification of
ichthyoplankton groups off Oregon.
Laroche and Richardson (1979)
investigated changes in the abundance and distribution of Parophrys
vetulus larvae during March and April, 1972-1975.
They presented
the first detailed analysis of the relationship of environmental
conditions to the annual abundance of fish larvae off Oregon.
Three distributional assemblages of larvae, coastal, transitional
and oceanic, were identified by Richardson et al. (1980) off the
Oregon coast.
Annual differences in the offshore occurrence of the
coastal assemblage were attributed to differences in local coastal
wind patterns.
Annual differences in the abundance of dominant
taxa were not explained, although Richardson et al. (1980)
5
speculated that feeding success, predation and competition may have
influenced the abundance of larvae.
Early life history stages of several north Pacific fishes have
been described from specimens taken in the studies discussed
previously:
Sebastolobus spp. (Pearcy, 1962), Ptilichthys goodei
(Richardson and Dehart, 1975), Sebastes spp. (Richardson and
Laroche, 1979; Laroche and Richardson, 1980, 1981), Macrouridae
(Stein, 1980), Cottidae (Richardson and Washington, 1980;
Richardson, 1981; Washington, 1982), Isopsetta isolepsis
(Richardson et a]., 1980), Embassichthys bathybius (Richardson,
1981) and Gadidae (Materese et al., 1981).
The Relationship of Environmental Factors to Larval Fish Abundance
Environmental factors that have been related to variations in
larval fish abundance include water temperature, salinity,
currents, upwelling strength, storms, food abundance, predation,
competition, spawning stock size and egg concentrations in species
with demersal eggs.
Many researchers have indicated that few of
these are independent (e.g. Colton and Temple, 1961; Ahistrom,
1965; Bannister et a]., 1974; Lasker, 1978; Laroche and Richardson,
1979).
Consequently, few studies have claimed that a single factor
is the direct cause of fluctuations in larval abundance.
It is currently thought that starvation and predation are the
proximate causes of larval fish mortality (Hunter, 1976).
This
mortality, in conjunction with the number of eggs spawned in each
year, will determine the annual variability in larval abundance.
Predators may feed on growing and starving larvae more frequently
than on those that are healthy and well fed (Ware, 1975; Hunter,
1976).
Therefore, all environmental factors that influence larval
mortality may ultimately be related to feeding success of the
larvae.
Although there is no single, comprehensive survey of
environmental effects on larval fish abundance, several authors
have reviewed aspects of the problem (Hempel, 1965, 1979; Gulland,
1965; May, 1974; Cushing, 1975; Hunter, 1976; Braum, 1978; Lasker,
1981b) and numerous studies are contained in three recent symposia
(Blaxter, 1974; Sharp, 1980; Lasker and Sherman, 1981).
Different environmental factors have been found to be
important influences on the abundance of larval fishes in different
oceanographic regions.
Intrusion of cold north Atlantic water into
the North Sea, with resulting altered zooplankton distributions,
was related to changed abundances of several species of fish larvae
(Hart, 1974; Coornbs, 1975).
Changes in zooplankton abundance in
the north Atlantic, particularly those of copepods, were directly
related to changes in larval fish abundance (Sysoeva and Degtereva,
1965; Bainbridge and Cooper, 1973; Robinson et al., 1975).
Currents at Georges Bank carried larvae into cold deep water away
from nursery grounds during certain years, causing mortality
(Walford, 1938; Colton, 1959; Colton and Temple, 1961).
High
surface water temperatures, lack of storms, low precipitation and
high salinities in Long Island Sound were related to high larval
abundances (Merriman and Sclar, 1952; Richards, 1959).
Upwelling
7
off California, with lowered water temperatures, offshore surface
water transport, increased abundances of inadequate food organisms,
disruption of upper mixed layer stability and disruption of eddy or
countercurrent systems, has been related to decreased larval
anchovy survival (Ahlstrom, 1965; Lasker and Smith, 1977; Lasker,
1981a).
Transport of larval Merluccius productus (Pacific hake)
off central California controls their distribution and is
a
significant factor in determining year-class strengths, with
offshore larval transport during upwelling leading to lower
survival (Bailey, 1981).
Predator abundance has been inversely
related to the abundance of larval Clupea harengus (Atlantic
herring) in the Baltic Sea (Möller, 1980) and larval Engraulis
mordax off California and Baja California (Alvario, 1980).
Three major hypotheses have been used to explain environmental
controls on larval fish survival in upwelling regions of the
northeastern Pacific Ocean.
Cushing (1969, 1975, 1978) suggested
that the spawning seasons of those fish species with discontinuous
seasons are matched to the peak of plankton productivity, and that
the match or mismatch of larval fish production with the production
of larval fish food organisms will determine year-class strengths.
From this hypothesis, one would expect the time of greatest larval
fish abundance to occur at the time of greatest plankton production
(Cushing, 1978).
0ff Oregon, the time of greatest productivity is
from June througn August, when strong upwelling occurs (Peterson
and Miller, 1975; Small and Menzies, 1981).
Lasker (1975, 1978,
1981a,b) suggested that prolonged stability of the upper mixed
layer is more important to the survival of Engraulis mordax larvae
than high primary productivity pse. Stability should be
conducive to the successful feeding of larvae in food patches, but
upwelling and storms would destabilize the mixed layer, disperse
patches and increase larval mortality.
Finally, Parrish et al.
(1981) suggested that most California Current region coastal fishes
spawn at times or in regions of reduced offshore transport, and
that anomalies in surface drift patterns are a major cause of
variation in the spawning success of fishes in upwelling zones.
These hypotheses are not exclusive, although each suggests a
different primary factor controlling larval fish survival.
Coastal Hydrography Off Oregon
The dominant hydrographic features off Oregon are the
California Current, the Davidson
Currents
variable alongshore
currents, the Columbia River plume, coastal upwelling and offshore
fronts (Pattullo and Denner, 1965; Huyer and Smith, 1978; Lough,
1975; Peterson and Miller, 1975; Rothlisberg, 1975; Peterson et
al., 1979).
Seasonal changes in prevailing winds control these
features nearshore.
From October through March, winds are usually
southwesterly, with frequent storms.
Runoff from coastal streams
and rainfall lower surface temperatures to as much as 9°C (Bourke
and Pattullo, 1974) and salinities by as much as 12°/oo (Pattullo
and Denner, 1965).
From April through September, winds are
northeasterly and cloud cover reduced.
Surface temperatures are
cooler and salinities are greater than in winter because of
upwell ing.
The southward flowing California Current off Oregon extends
from approximately 70 to 265 km offshore in the winter and 100-150
km in summer (Hickey, 1979).
Flows average 10.3 cm/s (Wooster and
Reid, 1963) although Wyatt et al. (1972) reported velocities of up
to 15.4 cm/s 0-200 km off Oregon, with a mean velocity of 5.7 cm/s.
A northward flowing, 15 km wide subsurface jet, at 20-40 cm/s,
occurs 15-20 km off Oregon (Hickey, 1979).
The Davidson Current, 75 km wide, is a nearshore surface
current that flows northward from about October through March-April
off Oregon (Burt and Wyatt, 1964; Wyatt et al., 1972).
Current
speed is approximately 2% of the prevailing wind velocity, with
highest current speeds about 10-24 hours after storms (Collins and
Pattullo, 1965).
Estimates of speeds are 0.0-28.8 cm/s (Burt and
Wyatt, 1964) and 25.7-102.8 cm/s, with highest speeds 32 km
offshore in November (Wyatt et al., 1972).
Winter northward flow
is present at all depths to at least 37 km offshore, with an
onshore component in the upper 10-20 m (Smith et al., 1971).
Variable alongshore currents occur in March, April and
September.
In the spring, surface flow changes from northward to
southward.
A vertical shear, with southward surface flow and a
northward undercurrent develops in late April (Huyer et al., 1975).
The Columbia River plume has been defined as a surface water
lens of salinity less than 32.5°/oo, often with salinities as low
as 20-25 0/00 and temperatures as high as 15°C at its core.
It
10
may be 20-24 m deep and extend 800 km from the river mouth in early
summer when runoff is greatest.
During the summer and fall, when
winds are northerly, the plume extends southwest of the river mouth
and is offshore.
In the winter and spring, when winds are
southerly, the plume extends north and is nearshore (Barnes et al.,
1972).
Plume velocities can be 12 cm/s at 111 km from the source
(Pak et al., 1970).
Upwelling occurs off Oregon from April through September and
is often strongest in June-August (Bakun, 1975).
It is most
pronounced equatorward of capes (Smith et al., 1971) and where
winds are at angles of 21.5° off the coast (Smith, 1968).
Upwelling effects may extend from the coast to about 50 km offshore
(Peterson et al., 1979), but are most intense 9-18 km offshore
(Bourke and Pattullo, 1974).
Upwelling strength lessens
exponentially offshore (Smith, 1968).
Offshore surface flow is
restricted to the upper lOm 0-10 km from shore and the upper 15 m
offshore (Peterson et al., 1979).
During early upwelling southward
surface velocities are 6 cm/s (Smith et al., 1966).
Vertical
velocities are 0.2x103 to 7.0x103 cm/s at 65 km offshore
(Smith et al., 1966).
During active upwelling, surface water 0 to
10-15 km offshore is 8-9°C and 33.5°/oo.
10-12°C during relaxed upwelling.
water is 10-12°C and 32.O_33.00/oo.
m has salinities of 33.0_33.50/oo.
Surface water warms to
Offshore of 10-15 km, upwelled
Deeper water at 10-20 to 60
Below 60 m, temperatures are
8-9°C and salinities are 33.50/00, like nearshore upwelled water
11
(Peterson et al., 1979).
Bourke and Pattullo (1974) found bottom
water at 30-50m 2-9 km offshore of 7°C and 34°/oo.
There is a region of alongshore frontal activity 9-18 km
offshore during the upwelling season, where coastal water mixes
with shelf and slope water (Bourke and Pattullo, 1974).
The front
has a southward flowing jet, strongest at the surface, 12-18 km
offshore (Huyer et al., 1975).
Jet velocities are 35 cm/s in late
spring and 20 cm/s in late summer (Small and Menzies, 1981).
In
May through July, the inner edge of the Columbia River plume may
form this front (Small and Menzies, 1981), and upwelled water
flowing offshore may submerge beneath the plume and front (Small
and Menzies, 1981).
Upwelling cells may exist on both sides of the front, with
water in the offshore cell rising along the pycnocline to the
surface at the front and moving offshore (Mooers et al., 1976).
Two models of nearshore circulation have been proposed.
Upwelled
water may rise along the pycnocline at the front, move shoreward at
10 m, and move seaward at the surface to be entrained in the jet at
the inner edge of the front, 7-12 km offshore (Peterson et al.,
1979).
Or, upwelled water may rise adjacent to the coast, move
seaward in the upper 20 m and descend along the pycnocline (Small
and Menzies, 1981).
Biotic Consequences of Coastal Currents Off Oregon
Alongshore flow off Oregon (30-50 cm/s) is greater than zonal
flow (6 cm/s) (Smith et al., 1966; Peterson and Miller, 1979).
12
Plankton populations may be latitudinally maintained because
current reversals result in little net north-south transport over a
season on the continental shelf (Richardson and Pearcy, 1977;
Peterson et al., 1979).
A surface front 15-28 km from shore may separate the coastal
and offshore Oregon ichthyoplankton assemblages.
This front has
been observed during upwelling, and may also be present in winter
(Richardson and Pearcy, 1977).
Differences in wind patterns may
chance the position of this front seasonally and annually, changing
the location of the transition between assemblages (Richardson et
al., 1980).
Chlorophyll concentrations off Oregon are highest 20-40 km
offshore during the upwelling season and consistently low
throughout winter.
During early or intermittent upwelling, a
biomass and productivity core is found just shoreward of the
Columbia River plume.
During prolonged strong upwelling in late
summer, this core is found farther offshore and a second core is
found at or inshore of the permanent pycnocline (Small and Menzies,
1981).
Peterson et al. (1979) found that zooplankton populations are
maintained in the Oregon upwelling zone, despite offshore
transport, and suggested as mechanisms cellular circulation, with
behavioral and ontogenetic changes in vertical distribution.
In
the nearshore upwelling cell zooplarikters avoid the thin surface
Ekman layer and remain in layers where offshore transport is
slight.
In the outer cell zooplankters move into deep layers of
13
onshore transport as adults.
In addition, surface circulation is
shoreward during relaxation of upwelling.
Upwelling events are
relatively brief in the outer cell, maintaining zooplankton
populations seaward of the offshore divergence.
Wroblewski (1980)
concluded that the maintainance of copepod populations in the
Oregon upwelling zone could be modeled by intermittent upwelling of
2-7 days duration, as observed by Huyer (1976), and that the
cellular gyre model was not necessary to explain how zooplankton
avoid offshore transport during upwelling.
The stability of the upper mixed layer may be disrupted by
storms and upwelling off Oregon as off California.
Phytoplankton
productivity is greatest during relaxed upwelling, while dilution
by mixing and offshore transport of biomass occurs during
persistent upwelling (Small and Menzies, 1981).
Food
concentrations for nearshore zooplankton populations are low during
prolonged intense upwelling, although zooplankton concentrations
remain high (Peterson et al., 1979).
14
MATERIALS AND METHODS
Field Sampling
The sampling regime has been described by Lough (1975, 1976),
Rothlisberg (1975), and Peterson and Miller (1975, 1976, 1977).
Plankton samples were taken 1.8, 5.6, 9.2 and 18.5 km offshore of
Newport, Oregon (Fig. 1) from 22 June 1969 to 5 August 1972. The
stations were designated NH1, NH3, NH5 and NH1O, respectively; the
numbers are their distance from shore in nautical miles.
The
transect initially originated at the mouth of Yaquina Bay (44°37'
N).
After 20 October 1970, it was moved 4 km to the north, off
Yaquina Head (44°41' N), to avoid estuarine runoff.
Samples were
taken at least twice monthly during 26 of the 37 months (App. III).
All stations were sampled at least once a month, except in April
1971 when only NH3 and 5 were sampled, and in Jan. -Feb. 1972 when
no samples were taken.
Of 277 samples, 267 (96.4%) were taken in
daylight, 6 (2.2%) were taken at night, and 4 (1.4%) were taken in
twil ight.
Plankton samples were collected with a 20.2 cm mouth diameter
bongo net (Posgay and Marak, 1980), illustrated in Rothlisberg
(1975) and Richardson (1977).
The bongo frames were fitted with
two 1.8 m long cylinder-cone Nitex nets.
The 0.233 mm and 0.571 mm
mesh nets on either side of the frame had filtering area to mouth
area ratios of 10.6 and 11.7.
Codends were PVC cylinders 9 cm in
diameter by 16 cm long, with laterally placed steel filtering
screens.
TSK (Tsurumi-Seiki Kosakusho Co., Litd.) flowmeters were
15
attached to the inside frame of each net.
calibrated in swimming pools.
Flowmeters were
A wire-scope to water-depth ratio of
2:1 was maintained by a 13.6 kg lead ball or a 6.8 kg fin depressor
until 4 November 1970, after which a modified 36.3 kg kite-otter
depressor (Colton, 1959) was used and 70 cm bongo nets were added
to the sampler.
A time depth recorder was attached below the nets
after 29 December 1971.
Step oblique tows of three to five levels were taken parallel
to the coast.
The nets lacked opening-closing devices, fishing
throughout the tow.
Samples were taken from bottom to surface,
with station depths of: NH1 = 20 m, NH3 = 46 m, NH5 = 59 m, and
NI-lb
= 85 m.
minutes.
Tow speeds were 2-3 knots and tow times were 4 to 42
Water volumes filtered per tow were 20.5 to 348.6 m3.
Surface temperatures, surface salinities and occasional bottom
salinities were taken prior to each tow.
Plankton samples were preserved immediately with 5-10%
formalin and buffered with sodium borate in the laboratory.
Laboratory Procedures
All fish larvae were sorted from the plankton samples.
Larvae
were stored in 5% formalin buffered to neutrality with sodium
borate.
All larvae were identified to the lowest possible
taxonomic group, measured and counted.
identified by Sharon Myers Roe1.
1
Most of the larvae were
Larval length was measured as
See Appendix I for taxonomic references.
Some identifications
were made with the unpublished work of Dr. S.L. Richardson and the
late Dr. E.H. Ahistrom.
notochord length before flexion, or as standard length during and
after flexion (Richardson, 1977).
Numbers of larvae taken per tow were standardized to numbers
of larvae beneath 10 in2 of sea surface (Smith and Richardson,
1977), except that numbers of larvae taken and water volumes
filtered in each side of the net were summed before
standardization, when larvae from both sides were available.
The
numbers and sizes of herring larvae from Yaquina Bay (Pearcy and
Myers, 1974), and kinds and numbers of crab larvae at NH3 (Lough,
1975) taken in both sides of the net were similar, indicating that
the two sides of the net did not differ in catch of large larvae.
Catches from both sides were combined to increase the sample size
of larvae at each station on each date, and because each side
filtered only a small volume of water during a single tow.
For
further analysis, the number of larvae per 10 in2 summed for all
stations sampled on a date is referred to as "total standardized
abundance," and the total standardized abundance divided by the
number of stations sampled on a date is referred to as the "mean
standardized abundance."
Salinity samples were analyzed with a CSIRO inductively
coupled sal inometer.
Additional Data
Hourly wind measurements taken from an anemometer at the south
jetty of Yaquina Bay were compiled into daily sums of north-south
and east-west components (William Gilbert, OSU School of
17
Oceanography, personal communication), and transposed into
progressive vector diagrams (Peterson and Miller, 1975, 1976,
1977).
Upwelling strength was estimated by daily and weekly values of
the coastal divergence index (=CDI11) or "upwelling index
1975).
(Bakun,
Wind stress curl (Nelson, 1976, 1977) was estimated with
daily values of the offshore divergence index (=ODI"; Andrew
Bakun, NMFS, NOAA, unpublished data).
The four combinations of
positive and negative CD1's and ODUs are coupled to four
hydrographic regimes of inshore vs. offshore convergence and
divergence (see Bakun and Parrish, 1980, Fig. 3).
Daily precipitation measurements and sporadic monthly weather
summaries reporting storms were taken from 1969-1972 climatological
reports for Newport, Oregon (U.S. Environmental Science Services
Administration, 1969-1972).
Relative cohort strengths of Parophrys vetulus and Isopsetta
isolepis from 1969-1972 were estimated from numbers of female P.
vetulus of each cohort taken per hour of fishing in 1972-1980 by
commercial fishing vessels in area 3A, and from the percent of I.
isolepis of each cohort in research survey catches off Oregon and
Washington in 1973-1975 (Robert Demory, Ore. Dept. Fisheries and
Wildlife, unpublished data:, method for P. vetulus from Ketchen and
Forrester, 1966).
For I. isolepis, the four cohorts were only
taken together in 1975, so their relative strengths were estimated
from the percentages of catch in that year.
For P. vetulus, cohort
strengths were estimated from the ranking of sums of the catches of
'SI
each cohort at ages 3-7, for which data were complete for all three
year-classes, in 1972-1980.
Dominance and Classification Analysis
Taxa were ranked by dominance using the Biological Index
(Richardson, 1973) modified from Eager (1957), which combines
abundance and frequency of occurrence.
The five most abundant taxa
were ranked within each sample (the combined catches of the two
nets in a single tow), the ranks summed among all samples for each
taxon and the summed ranks divided by the number of samples,
yielding the final dominance rankings.
Cluster classification techniques (Clifford and Stevenson,
1975; Boesch, 1977), from Richardson (1976), were used to identify
seasonal species associations (species-groups) and faurially similar
sampling dates (time-groups).
Before analysis, a two-dimensional
data matrix of species abundances x sampling times was created by
summing the abundances of each taxon over all stations sampled per
time.
Only data from the 64 times on which all four stations were
sampled were included in the analysis, to eliminate the effects of
unequal sampling effort.
Taxa occurring less than 5% of the times
were eliminated from the analysis, because rare taxa do not
contribute to recurrent species or time-groups and may obscure
patterns in the classification (Clifford and Stevenson, 1975).
Abundances were multiplied by 10, becoming numbers of larvae per
100 m2, because the algorithms used required all abundances to be
greater than 1 (Richardson, 1976).
A log10(n+1) transformation
19
(Barnes, 1952), where n=# larvae/lOU m2, was applied to remove
skewness caused by a few high abundances of the Osmeridae,
Parophrys vetulus and Isopsetta isolepis.
Abundances of larvae
were standardized to proportions in the classification of time
groups by dividing the abundance of a taxon at a single time by its
total abundance at all times.
This standardization gives more
weight to frequency of occurrence than abundance (Clifford and
Stevenson, 1975).
No standardization was used in the
classification of species-groups, giving more weight to abundance.
The Bray-Curtis dissimilarity coefficient was chosen because
it is sensitive to abundance (Clifford and Stevenson, 1975) and has
been used to identify geographic ichthyoplankton groups off Oregon
(Richardson and Stevenson, 1978; Richardson et al., 1980).
The
coefficient is calculated as:
n
D.k =
X jXjk
i
?:
when
(xjj+xjk)
is the dissimilarity between sampling times j and k,
is the abundance of the
th
species from the
th
time, and Xik is the abundance of the
sampling time.
and k,
i
th
sampling
species on the kth
When Dik is the dissimilarity between species .j
refers to a sampling time.
Bray-Curtis values range
between 0, for complete similarity, and 1, for complete
dissimilarity (Boesch, 1977).
A group average sorting strategy (Clifford and Stevenson,
1975) was used to cluster the dissimilarity coefficients.
The
20
method was explained in detail by Sneath and Sokal (1973) under the
name "unweighted pair-group method using arithmetic averages
(UPGMA)."
Sampling times were classified by the abundance of species
occurring on each date, treating times as sampling stations have
been treated in most other ecological classifications (Williams and
Stevenson, 1973).
The classification of species-groups occurring
at different times was completed as that for species-groups
occurring at different stations (Clifford and Stevenson, 1975).
Time and species-groups were initially classified from data
including all abundant taxa.
Species-groups from this
classification were not well defined, because several higher taxa
that included several species were abundant throughout the year.
A
second classification was then formed from data excluding the
Osmeridae, Cyclopteridae and Sebastes species.
Separate classifications were formed for each year,
facilitating both comparisons of time and species-groups among
years and identification of differences between years.
A year was
considered to begin on 1 September and end on 31 August, because
the season of lowest larval abundance began at that time in each
year (see RESULTS).
Classifications are presented as dendrograms.
Species and
time-groups identified were those that formed at or below the
subjectively chosen 0.55 dissimilarity level.
The relationships of
species-groups to time-groups are presented in two-way coincidence
tables.
Coincidences are the frequencies (%) with which the
21
members of a species-group occur within a time-group (Boesch,
1977).
The coincidence tab'es show the times of peak occurrence
and seasonal range of occurrence for each species-group.
A Kruskal-Wallis test was used to determine if differences in
the variance of larval fish abundances existed between years,
compared to the variance within years.
A non-parametric test was
used after graphic rankit analysis (Sokal and Rohif, 1969) showed
departure of the data from a normal frequency distribution, not
corrected by a 1og10(n+1) transformation.
22
RESULTS
Sampling Gear Efficiency
Although bongo nets are recommended sampling gear for ichthyo-
plankton surveys, the 20 cm mouth diameter is smaller than the 70
cm diameter suggested as adequate for such surveys (Smith and
Richardson, 1977; Bowles et a]., 1978).
Gear size influences the
number and size of larvae captured (Barkley, 1964; Bowles et al.,
1978).
Efficiency of the 20 cm nets was evaluated by comparing the
catch of that gear to the catch of 70 cm bongo nets, taken concurrently in 1971 and 1972 (Richardson, 1977).
Abundances of larvae were often underestimated by the 20 cm
nets.
To evaluate this, total standardized abundances (E#/10 m2)
from the 20 cm bongo net samples at each station on each date were
compared to those from the 70 cm nets (Richardson, 1977; Table
104).
Although the catches of the two nets were correlated (r
0.88), a Wilcoxon's signed rank test for differences between the
catches of the two nets was significant (P = 0.05).
Catches in the
20 cm nets were smaller than in the 70 cm nets in 67 of 111 paired
comparisons (60.4%).
In addition to smaller abundance estimates, fewer taxa were
taken in the 20 cm nets.
Eight rare species were taken only by the
70 cm nets at NH 1-10 (Richardson, 1977).
taken only by the 20 cm nets.
One rare species was
Fewer species were taken by the
smaller nets because less water was filtered per sample than by the
larger nets.
23
Avoidance of the smaller nets was demonstrated by the smaller
sizes of larvae taken in the 20 cm nets.
In a comparison of
monthly ranges and modes of lengths of 13 dominant taxa taken in
1971 by the 20 cm and 70 cm nets (Richardson and Pearcy, 1977;
Table 6), 61.1% of the modal monthly lengths and 76.6% of the
maximum monthly lengths were larger in catches of the 70 cm nets.
Smaller catches, a lower species number and smaller sizes of
larvae were taken by the 20 cm bongo nets, compared to 70 cm nets.
However, the correlation between the catches (# larvae/10 m2) of
the two sizes of bongo nets [20 cm net catch = 4.61 + 1.03 (70 cm
net catch); r
0.88] indicated that comparisons of numbers of
larvae from 20 cm net samples relative to one another through time
were valid estimates of relative temporal changes in the abundance
of fish larvae.
Overall Species Composition and Dominant
pecies
Larval fish were taken in 194 of the 277 samples.
The samples
contained 5470 larvae, which were identified to 57 taxa in 21
families and 43 genera (App. II).
Osmerids dominated in both
abundance and frequency of occurrence; 54.13% of the catch and
42.31% of the total standardized abundance (z#/ 10 m2) were smelt
larvae.
Biological Index values (Richardson, 1973) ranged from 1.61
for the Osmeridae to 0.00 for two taxa which were never among the
five most abundant taxa in any sample (App. II).
The 13 dominant
taxa, with Biological Indices of 0.15 or greater (Table IV) were,
24
in descending order of rank: Osmeridae (smelts), Parophrys vetulus
(English sole), Isopsetta isolepis (butter sole), Psettichthys
melanostictus (sand sole), Microgadus proximus (Pacific tomcod),
Sebastes spp. (rockfishes), Artedius harringtoni (scalyhead
sculpin), Ammodytes hexapterus (Pacific sand lance), Platichthys
stellatus (starry flounder), Lyopsetta exilis (slender sole),
Artedius meanyi (Puget Sound sculpin), Artedius fenestralis (padded
sculpin) and Cyclopteridae type 1 (snailfishes).
ranking
14th
The species
was a mesopelagic form, Stenobrachius leucopsarus
(northern lampfish; App. II), and not part of the coastal species
assemblage (Richardson and Pearcy, 1977).
The 13 dominant taxa
accounted for 94.25% of the larvae taken and 93.33% of the total
standardized abundance of larvae.
Only the 13 dominant taxa will
be discussed individually.
The Annual Cycle of Larval Fish Abundance in Oregon Coastal Waters
Two peaks of abundance and a period of low abundance occurred
in each year (Figs. 2-4).
The largest mean numbers of larvae (>100
larvae! 10 m2) were found in February and again in May- early July.
These peaks were usually composed of taxa from different seasonal
species-groups.
Late September was always a time of extremely low
larval abundance, and dates when no larvae were captured occurred
in late August or September of each year.
Those few larvae which
were taken in late September were large specimens of only four
taxa.
Therefore, the annual cycle of ichthyoplankton abundance in
25
Oregon coastal waters is considered to begin on 1 Sept. and end on
31 Aug. in each year.
Annual Variations in Larval Fish Occurrences, 1969-1972
Four time-groups were found at dissimilarity values
Sept. 1969 - Aug. 1970 (Fig. 5a).
O.55 in
September and October 1969 were
not included in a group because only multiple species taxa were
taken then.
Time-group 1 included dates in November and December.
Time-group 2, which was most similar in Bray-Curtis value to group
1, included dates from January and February 1970.
March was not
included in a group, but was most similar to group 2.
A spring
group, time-group 3, including April and May, was less similar to
the previous two groups than the two were to each other.
Dates
from the summer were not clustered into a group, but were similar
to group 3.
Group 4, consisting of dates in September and July,
was a late-summer group.
Five species groups were found in 1969-70
(Fig. Sb) and were associated with time-groups (Table II) by
two-way coincidence tables (Table Ia).
Species-group 1, composed
of larvae occurring only in winter, included Ophiodon elongatus,
Hemilepidotus spinosus and Ammodytes hexapterus.
Species-group 2,
Anoplarchus sp. and Platichthys stellatus, was also a winter group.
Group 4, Clinocottus acuticeps and Lyopsetta exilis, occurred in
spring, first appearing in April.
Group 3, Microgadus proximus and
Artedius feriestralis, was found in late winter, spring and early
summer (Feb. - Aug.), but did not become abundant until late May.
Group S included Artedius harringtoni, A. meanyi, Isopsetta
26
isolepis and Psettichthys melanostictus, and was found from
February through August.
Parophry
vetulus was not included in a
group, but was similar to species-groups 3 and 5 in its times of
occurrence in 1969-70.
Major differences were seen in the dendrograms for Sept. 1970Aug. 1971 (Fig. 6a + b) compared to those for 1969-70.
time-groups occurred in 1970-71 (Fig. 6a).
1970 did not form a group.
Four
The autumn months of
Time-group 1 from 1970-71 included
dates in December and January.
Group 2 included only February.
A
major difference between 1970-71 and 1969-70 was that February was
grouped more closely to spring and summer months than winter months
in 1970-71, and more closely to January than spring and summer
months in 1969-70.
Time-group 3 in 1970-71 included May and early
June, while late June and early July formed group 4.
Species-groups in 1970-71 were very different from those in the
previous year (Fig. 6b).
No equivalents of the winter
species-groups (1 and 2, Fig. 5b) were found in 1970-71.
Some
winter species, e.g. Ophiodon elongatus and Clupea harengus, were
not taken in 1970-71.
Parophrys vetulus and Hemilepidotus spinosus
formed species-group 1 in 1970-71, which occurred constantly from
December through February (Tables Ib,II).
In contrast to 1969-70,
species-groups that occurred primarily in the spring and summer
were also well represented in February.
Species-group 2, Enophrys
bison and Pholis spp., occurred from February through June.
Species-groups 3, equivalent to group 4 of 1969-70 in species
composition, occurred primarily from February through August.
27
Species-group 4 (groups 3 + 5 in 1969-70), which was the largest
group, also occurred primarily from February through August.
The dendrograms for Sept. 1971 - Aug. 1972 (Fig. 7a,b) were
more like those from 1969-70 than 1970-71.
No samples were taken
in January-February 1972, causing the winter time-group and
species-group to be missing in the classification analysis for
1971-72.
Four-time groups were found in 1971-72 (Fig. 7a): group
1, consisting of Sept. - Nov.; group 2, including only dates in
March; group 3, including April - mid June; and group 4, composed
of dates in June-August.
1971-72 (Fig. 7b).
Only three species-groups were found in
The two-way coincidence table for 1971-72
(Table Ic) indicated that none of the species-groups were found in
the first time-group.
In 1971-72, species-group I contained
species considered both winter and spring species in other years,
including dominants
Ammodytes hexapterus and Microgadus proximus.
Species-group 1 occurred from March through June, but was most
abundant in March.
Species-group 2, containing Isopsetta isolepis
and two Artedius species, occurred from March through August, but
was most abundant in April - June.
Species-group 3, found in April
- mid June 1972, was composed of species usually included in
smaller groups during the other years.
When multiple species taxa were included in the
classifications, the Osmeridae and Cyclopteridae type 1 were placed
in the species-groups which included Isopsetta isolepis, and
Sebastes spp. formed groups with Parophrys vetulus.
Major differences and similarities between years are as
follows.
In 1969-70, the winter season included Nov.- March.
well defined, abundant winter species-group was present.
vetulus larvae were present from December through May.
A
Parophrys
Species
from the spring and summer groups were found from April through
September.
In 1970-71, no winter species group was identified and
only December and January were classified as winter months.
Parophrys vetulus were found from November through June.
February
was classified with the spring time-group, which indicated a short
winter.
Species from the spring and summer groups were found from
February through August.
The final year, 1971-72, was more like
1969-70 than 1970-71 in occurrence of species-groups within
time-groups. Assessment of the winter season in 1971-72 was
difficult because January and February were not sampled.
species in 1971-72 were classified with spring species.
Winter
Species
composition and abundances from December 1971 and March 1972
indicated that a well-defined winter season and winter
species-group were present in 1971-72.
However, 1969-70 remained
the only year in which a winter species-group was actually found.
Parophrys vetulus larvae had a short season of occurrence, from
October through March.
Species in the spring and summer
species-groups occurred from March through August, earlier than in
1969-70 but later than in 1970-71.
29
The Annual Cycle of Larval Fish Species-Group Occurrences in
Coastal Waters Off Oregon
The annual cycle of species-group occurrences in Oregon
coastal waters was induced from similarities in patterns among the
three years (Figs. 5-7; Table II).
vetulus and Sebastes spp. appear.
In late fall, larval Parophrys
These species contribute to the
high abundances of winter species in January and February, and
persist into May or June.
Winter spawning species from two
species-groups appear in January and persist through April in most
years.
The most abundant species, Ammodytes hexapterus, has a
short larval occurrence with peak abundances in February and March.
Species in the spring-summer groups appear in mid-winter but do not
become abundant until March or April.
The Osmeridae is composed of
several species; the presence of smelt larvae in all months may be
due to different spawning seasons of different smelt species off
Oregon.
However, most smelt larvae were found in January-March and
April-June.
Other spring-summer taxa either were most abundant in
May and June or were evenly abundant throughout their season of
occurrence.
Large numbers of larvae found in May and June (Figs.
2-4) were due primarily to high abundances of osmerid larvae,
although other species in the spring-summer groups also contributed
to those peaks (Table II).
Low numbers of larvae in April relative
to February and May reflected the transition of the larval fish
fauna from winter species-groups to spring-sumer species-groups
(Figs. 2-4).
Most spawning had ceased and most larvae were
transformed by August or September.
30
Annual Variation in the Relative Dominance (Biological Index)
and
Abundance (#/10 m2) of Dominant Taxa
The ranking of Biological Index values of the dominant taxa
differed among years (Table IV).
dominant taxon in each year.
second or third.
Smelt larvae were the most
Isopsetta isolepis were always ranked
Parophrys vetulus were ranked second in 1969-70,
third in 1970-71 and fifth in 1971-72.
Microgadus proximus were
ranked only ninth in 1969-70, but were fourth in 1970-71.
Psettichthys melanostictus were ranked fourth in both 1969-70 and
1971-72, but were only ranked thirteenth in 1970-71.
Artedius
harringtoni decreased in rank over the three years, while
Platichthys stellatus showed a progressive increase in rank.
The
changes in rank among the dominant species indicated changes in
their relative abundance, compared to those of other species, among
years.
When differences in ranks of abundance of the 13 dominant taxa
and of all taxa combined were calculated over all months between
years (Table III: Kruskal-Wallis test), only the Osmeridae were
found to have significantly different annual abundances (P = 0.05,
2 d.f.).
The small sample size, three years, with a resulting low
number of degrees of freedom partially explains why only the
Osmeridae were found to differ significantly in abundance among
years.
Despite the test results, annual differences in the
occurrences and composition of seasonal species-groups, and in rank
31
orders of dominance were obvious (Tables III and IV).
In addition,
annual differences in the seasonal occurrence, abundance (#110 m2)
and length frequency composition of most dominant species seemed
biologically meaningful (Figs. 8-20).
Hence, further analysis
seemed appropriate.
Annual Variability in the Abundance (#110 m2) and Size
Cposition of the Dominant Taxa
Osmeridae (smelts)
The five species of smelt that spawn off Oregon hatch at 3-7
mm and absorb the yolk by 6-10 mm (Schaeffer, 1936; Yap-chiongco,
1949; Parente and Snyder, 1970; Hart, 1973; Wang, 1981).
Although
information on transformation size is scarce for those species,
osmerids transform at approximately 30-40 mm (Yap-chiongco, 1949;
Cooper, 1978; Wang, 1981).
Recently hatched and transforminci smelt, remnants of spring
and summer 1969 spawnings, were taken in July-Sept. 1969 (Fig. 8).
Recently hatched larvae were taken in Dec. 1969- May 1970.
Larger
larvae resulting from this cohort were found in April-July and Oct.
1970.
A second influx of newly hatched smelt was found in
July-Dec. 1970.
The mean abundance of smelt larvae in May 1970 was
1/14 that in May 1971. Fewer large larvae (>30 mm), found only in
Sept. 1969 and July 1970 of that year, were found in 1969-70
compared to 1970-71.
The mean annual abundance of smelt larvae was
7.28/10 m2 in 1969-70, compared to 46.46/10 m2 in 1970-71 and
16.51/10 m2 in 1971-72.
32
During Sept. - Dec. 1970, few (mean = 4.0/10 m2) recently
hatched smelt were taken.
More (mean = 19.1/10 m2) were found in
Jan. - March 1971, with slightly larger modal lengths (10 mm) in
March than Jan. - Feb., indicating growth of a cohort.
larvae were taken in April.
No small
Very large numbers (mean = 125.6/10
m2) of smelt larvae were found in May 1971, persisting through
June.
This influx of smelt was the largest of any species at any
time in this study.
The modal length of smelt larvae in early May
was at the upper end of hatching range (10 mm), which suggested
that either extrusion of small larvae was a problem or that
spawning occurred outside of the sampling area with larvae growing
as they were advected into the area.
The presence of smaller smelt
larvae in the samples at other times of the year, and of smaller
larvae of other species, suggested that the latter explanation was
true.
More (mean = 43.3/10 m2) larvae at transformation sizes (30
mm) were taken in May-Aug. 1971 than in the other years.
There
were three modal lengths (8, 14, and 20 mm) for smelt larvae in
late May 1971 which persisted through July, indicating multiple
spawning peaks in 1971.
Many (mean = 39.3/10 m2) recently hatched smelt larvae were
taken in March 1972, but few (mean
found in April.
2.6/10 m2) of any size were
Large numbers (mean = 120.5/10 m2) were taken in
May.
Most were larger than 10mm, with two modal lengths (12 and 17
mm).
Few (mean = 0.6/10 m2) larvae less than 9 mm long were found
in May 1972, as in May 1971.
Very few (mean = 0.4/10 m2)
transforming sized larvae (30 mm) were taken in June - Aug. 1972.
33
Parophrys vetulus (English sole)
English sole larvae hatch at 2.6-2.9 mm, absorb their yolk at
3.7-4.5 mm and transform at 18-22 mm (Misitano, 1976; Laroche et
al., 1982).
There were strong annual differences in the abundance
and time of occurrence of English sole larvae (Fig. 9).
In 1969, recently hatched (<5 mm) larval English sole were
very abundant (mean = 37.3/10 m2) in November.
Many (mean =
12.2/10 m2) 5-17 mm and one 18 mm English sole were found in
December.
Only two were taken in January.
Large numbers (mean =
14.8/10 m2) of recently hatched larvae were taken again in Feb. March (Fig. 9).
1969-70.
There were two spawning speaks of English sole in
Larvae of progressively larger sizes from the second peak
were captured from February through June 1970, and larvae larger
than 17 mm were taken in April and June.
Transforming larvae were
found only in 1969-70.
In the second year, small English sole larvae were found from
Dec. 1970 through March 1971, but were not abundant until February.
The largest number (mean = 109.0/10 m2) of English sole found in
any month of any year was taken in Feb. 1971.
Unlike the previous
year, only one spawning peak of English sole was found in 1970-71.
Larvae 5-17 mm long were moderately abundant (mean
March-May 1971.
9.7/10 m2) in
The mean abundance of larval English sole in
1970-71 was 12.93/10 m2, compared to 6.13/10 m2 in 1969-70 and
2.63/10 m2 in 1971-72.
34
They were least abundant in the third year.
3.33/10 m2) were found in Oct. - Nov. 1971.
Few (mean =
Recently hatched and
5-12 mm larvae were abundant (mean = 27.4/10 m2) in December.
The
lack of samples in Feb. 1972 was unfortunate, because February was
the month when English sole larvae were most abundant in other
years.
However, only one English sole larva was taken in 1972,
during March, which indicated that they were not abundant in that
year.
Isopsetta isolepis (butter sole)
Butter sole larvae hatch at 2.68-2.92 mm, absorb the yolk at
3.8-4.0 mm and transform at 18-23 mm (Richardson et al.,1980).
Differences in the abundance and size structure of the larval
butter sole catch in the three years were obvious (Fig. 10).
A few (mean = 2.8/10 m2) larvae, larger than 10 mm, were found
in Aug. - Sept. 1969.
1969 - April 1970.
Recently hatched specimens were found in Dec.
Many (mean = 64.5/10 m2) larger larvae (modes
4 and 7 mm) were present in April.
This cohort was abundant (mean
= 13.4/10 m2), with a larger modal size (10 mm) in May.
However,
only one specimen (11 mm) was found after May in 1971.
The mean abundance of butter sole larvae per 10 m2 was 3.39 in
1970-71, compared to 9.70 in 1969-70 and 5.35 in 1971-72.
hatched specimens were taken in Feb.- March 1971.
Butter sole
larvae were very abundant (mean = 48.6/10 m2) in May 1971.
approaching transformation were abundant (mean = 4.7/10 m2)
relative to other years from May through June 1971.
Recently
Larvae
35
The size distribution of butter sole larvae in 1971-72 was
more similar to that in 1969-70 than 1970-71.
larvae were present in March-April 1972.
Recently hatched
Many (mean = 36.4/10 m2)
6-13 mm specimens were found in May 1972, but they were less
abundant than in May 1971.
Only a few (mean = 2.0/10 m2) 14-19 mm
specimens were found in June-July 1972.
Psettichthys melanostictus (sand sole)
Sand sole larvae hatch at a mean length of 2.8 mm, the yolk is
absorbed at approximately 4 mm and transformation occurs at 22-28
mm (Hickman, 1959).
In 1969-72, sand sole were highly variable in
their months of occurrence (Fig. 11).
In 1969, a few large sand sole larvae from spawnings earlier
in the year were taken in July and August.
were also found in August.
In 1969-70, recently hatched sand sole
larvae were taken in March-April.
April 1970 was the month of
greatest larval sand sole abundance (mean
three years.
Recently hatched larvae
88.9/10 m2) of all
The larvae larger than 14 mm from April indicated
that spawning either occurred earlier in the year than indicated by
catches of small larvae or that large larvae were advected into the
study area from other spawning sites.
Larval sand sole were
moderately abundant (mean = 8.0/10 m2) in May, with an increase in
modal size (10 mm) from that in April (5 and 7 mm).
Sand sole
larvae larger than 20 mm were taken only in April, May and August
1970 in this study.
The mean abundance of sand sole larvae in
1969-70 was 3.03/10 m2, compared to 1.30/10 m2 in 1970-71 and
36
2.67/10 m2 in 1971-72.
There was only one spawning peak of sand
sole in 1969-70.
In 1970-71, recently hatched sand sole were found in Feb.May.
Larger larvae were taken through July, with the highest mean
abundance (4.9/10 m2) in July.
This was later than the time of
greatest abundance in the previous year.
Single large sand sole
were taken in August and September.
In 1971-72, unlike other years, recently hatched larvae
occurred in Oct.- Nov. as well as in the spring (March-April).
There were two spawning peaks in 1971-72.
Larvae from the autumn
spawning were not as abundant as those from the spring spawning of
of any year.
In the spring, sand sole larvae were abundant (mean =
17.6/10 m2) in May but only a single specimen was found after May
in 1972, unlike other years.
Microgadus proximus (Pacific tomcod)
Pacific tomcod hatch at 2.7 mm, the yolk is absorbed at 3.0 mm
and transformation occurs at 22.0-28.0 mm (Materese et a]., 1981).
In 1969-70, small tomcod larvae (<4 mm) were present in Jan.April and in July (Fig. 12).
Very few larger larvae (mean
0.3/10
m2) were taken in May-July 1970, with none close to transformation.
The mean abundance, of tomcod larvae per 10 m2 in 1969-70 was 0.39,
compared to 3.33 in 1970-71 and 1.84 in 1971-72.
Recently hatched tomcod larvae were taken in Feb.- March and
May 1971, which indicated two spawning peaks.
Two size-groups (4-5
and 18-25 mm) of tomcod larvae were found in June-July 1971.
The
37
largest mean abundances (14.0 and 8.0/10 m2) of tomcod in the three
years were found in May and June 1971.
The only specimens nearing
transformation (>22 mm) were found in June-Aug.
1971.
Newly hatched tomcod were more abundant (mean = 2.0/10 m2) in
March-April 1972 than in those months in the other years.
The
occurrence of larvae smaller than 4 mm indicated two spawning
peaks; one just prior to March and another from the last week of
March into April.
However, few (6) larvae larger than 6 mm were
taken in 1972, and no tomcod were found after May in 1972.
Sebastes spp. (rockfishes)
Larvae of most northeastern Pacific Sebastes species are born
at 3.8-7.5 mm.
al., 1977).
Notochord flexion occurs at 7.0-11.8 mm (Moser et
Rockfish larvae transform at 15-27 mm (Moser et al.,
1977; Laroche and Richardson, 1981).
Postflexion larvae were only
taken on 9 Oct. 1970 and 3 August 1971.
taken were 2-6 mm long (Fig. 13).
All other rockfish larvae
The absence of larger larvae may
have been due to net avoidance and offshore advection of larvae
soon after parturition.
Large pelagic rockfish larvae and
prejuveniles have been collected off Oregon with larger nets.
Most
were collected farther offshore than 18.5 km (Richardson, 1977;
Richardson and Pearcy, 1977; Richardson and Laroche, 1979; Laroche
and Richardson, 1980,1981).
Rockfish larvae are members of the
offshore Oregon ichthyoplankton assemblage (Richardson and Pearcy,
1977; Richardson et al., 1980).
CI:1
Small rockfish larvae were abundant (mean = 3.0/10 m2) in Dec.
1969
Feb. 1970, Dec. 1970 - Feb. 1971 and March-April 1972.
The
annual mean abundance of rockfish larvae per 10 m2 was 4.51 in
1969-70, 1.82 in 1970-71 and 1.29 in 1971-72.
Differences in the
occurrences of rockfish larvae cannot be interpreted because the
larvae could not be identified to species.
Thirty-six species of
Sebastes occur off Oregon (Richardson and Laroche, 1979).
Artedius harringtoni (scalyhead sculpin)
Scalyhead sculpins hatch at 3.0-4.0 mm, flexion occurs at 5.2
mm, fin-ray formation is complete by 10 mm and transformation
occurs at 13-14 mm (Richardson and Washington, 1980; Washington,
1982).
Recently hatched specimens were taken in June-Aug. 1969 and
larvae larger than 9 mm were found in June-July 1969 (Fig. 14).
In
1969-70, no scalyhead sculpins were taken in Jan.- March, but small
(<6 mm) specimens were found in April-June and larger ones in
May-July.
The absence of scalyhead sculpins in Jan.- March 1970
was exceptional among the three years.
In 1970-71, larvae 5 mm or
less were taken in Jan.- Aug., and larvae larger than 9 mm were
found in May-June and August 1971.
In 1972, Jan.- Feb. were not
sampled, but recently hatched larvae were present in March-June.
The mean annual abundance of scalyhead sculpin larvae per 10
m2 was 0.63 in 1969-70, 1.38 in 1970-71 and 2.39 in 1971-72.
39
Ammodytes hexapterus (Pacific sand lance)
Sand lance larvae hatch at 3-7 mm, the yolk is absorbed at
5-7.5 mm and fins form by 22 mm with transformation occurring at a
larger size (Fritzsche, 1978).
Sand lance larvae smaller than 7 mm were taken in Jan.- Feb.
1970, Feb.- March 1971 and March 1972 (Fig. 15), suggesting a brief
winter spawning season.
No larvae larger than 14 mm were taken.
Large sand lance larvae may be good avoiders of plankton nets
(Richardson and Pearcy, 1977).
The mean annual abundance per 10 m2
of post-flexion larvae larger than 9 mm was 0.04 in 1969-70, 0.30
in 1970-71 and 0.16 in 1971-72.
The mean abundance of smaller
larvae was 1.88 in 1969-70, 0.64 in 1970-71 and 1.17 in 1971-72.
Abundances of sand lance larvae in 1972 were underestimated because
no samples were taken in Jan.- Feb., months when sand lance were
abundant in other years.
Platichthys stellatus (starry flounder)
Starry flounder larvae hatch at approximately 2 mm (Orcutt,
1950) and transform at 8-9 mm (Richardson and Pearcy, 1977).
Starry flounders were rare in 1969-70 (Fig. 16).
Only single
specimens were taken in July 1969, Feb. 1970 and March 1970.
The
specimen from March had hatched recently.
During 1970-71, larvae smaller than 6 mm were taken in
February and April 1971.
None were taken in March.
Many starry
flounder (mean = 10.6/10 n-i2) including recently hatched and
40
transforming larvae, were taken in May.
A few (mean = 1.0/10 m2)
starry flounder 5-8 mm long were found in June.
In 1971-72, several (mean = 4.6/10 m2) recently hatched larvae
were taken in March-April.
Many (mean = 14.5/10 m2) specimens
larger than 6 mm were found in May.
The mean annual abundance per 10 m2 of starry flounder larvae
was 0.06 in 1969-70, 1.61 in 1970-71 and 2.69 in 1971-72.
Lyopsetta exilis (slender sole)
Slender sole hatch at 5 mm and transform at 18-22 mm (Ahlstroni
and Moser, 1975).
Larvae smaller than 6 mm were taken in April-May
1970 and March and May-June 1971.
Larvae larger than 15 mm were
found in July 1969, May 1970, July 1971 and July 1972, but were
never common (Fig. 17).
In 1969-70, slender sole larvae were only f' und in April-May.
In 1970-71, they occurred in more months, March-July, than in the
other two years and were most abundant (mean = 2.4/10 m2) in
May-July.
In 1971-72, they occurred in May and June.
The mean
annual abundance per 10 m2 of slender sole larvae was 0.57 in
1969-70, 0.83 in 1970-71 and 0.72 in 1971-72, which suggested
little annual variability.
Artedius meanyi (Puget Sound sculpin)
Puget Sound sculpin hatch at 3.4 mm, flexion begins at approximately 6.2 mm and transformation occurs at 15-16 mm (Richardson
and Washington, 1980 as Icelinus spp.; Washington, 1982).
41
Relatively few Puget Sound sculpins (76) were taken. Post-
flexion larvae were more abundant (mean = 1.6/10 in2) in July-Aug.
1969 than in any of the full three years sampled, suggesting high
abundances for this species in 1968-69. In 1969-70, recently
hatched larvae were found in Feb.- April and a single specimen
approaching transformation was found in June (Fig. 18).
More Puget
Sound sculpins (mean = 3.9/10 m2) were found in May 1970 than in
any other month of this study, but very few (mean = 0.5/10 in2) were
taken in June-July 1970.
In 1970-71, recently hatched larvae were
taken in March and June.
Only two specimens were taken in 1971-72.
The mean annual abundance per 10 in2 of Puget Sound sculpin was 0.67
in 1969-70, 0.35 in 1970-71 and 0.17 in 1971-72.
Artedius fenestralis (padded sculpin)
Larval padded sculpins hatch at 3.5-3.8 mm, flexion occurs at
6 mm and transformation begins at 12-14 mm (Richardson and
Washington, 1980; Washington, 1982).
Larvae smaller than 5 mm were
taken in Jan.- March 1970, Jan.- Feb., June and Aug. 1971, and
March-April 1972 (Fig. 19).
in this study.
Larvae 12 mm or longer were not taken
Padded sculpin occurred from January through August
in each year and were most abundant in April or May.
The mean
annual abundance per 10 in2 of padded sculpin larvae was 0.37 in
1969-70, 0.62 in 1970-71 and 0.70 in 1971-72, suggesting little
annual variation in the abundance of this species.
42
Cyclopteridae Type 1 (snailfishes)
This was another taxon that was probably composed of several
species.
Too few specimens (24) were taken for annual differences
in abundance or trends in spawning and growth to be seen (Fig. 20).
Spatial Distribution of the Dominant Taxa
Smelt larvae occurred at all stations at various times, but
were usually most abundant at 2-6 km from shore.
not taken at 18 km.
They were usually
Parophrys vetulus were abundant at all
stations at various times.
Large numbers of English sole were
found at 2-9 km in Jan. - March 1971.
Isopsetta isolepis were often
dispersed along all stations, but the largest concentrations were
found at 6 and 9 km.
Psettichthys melanostictus were temporally
and spatially patchy in distribution, but their highest
concentrations were found primarily at 6-9 km.
Microgadus proximus
occurred at all stations, but were most abundant at 6-9 km.
Sebastes spp. were most abundant at 18 km, unlike the other
dominant taxa.
In addition, large numbers of small rockfish
occasionally occurred patchily at single stations on single dates
(18 km on 29 Dec. 1969, 2 km on 13 Jan. 1970, 18 km on 3 Feb. 1970,
18 km on 21 Dec. 1970 and 6 km on 18 Jan. 1971).
Artedius
harringtoni were most abundant at 6-9 km, although they occurred
frequently at 2 km.
1971.
They were found only at 18 km in Jan. - March
Ammodytes hexapterus larvae were found only for a few weeks
in each year and were spatially very patchy in distribution.
were most abundant at 6-18 km.
They
Platichthys stellatus larvae were
43
most abundant at 2-9 km. with their highest concentrations at 2-6
km.
They were found at 18 km once.
Lyopsetta exilis larvae were
patchy, most abundant at 6-18 km. and were found at 2 km once.
Artedius meanyi were most abundant at 6-9 km, occurring only once
at 18 km and twice at 2 km.
A. fenestralis were found at 2-9 km,
but were most abundant at 6-9 km.
They were taken at 18 km once.
Cyclopterids were occasionally abundant at 6-18 km.
Weather Conditions from June 1969 through August 1972
(From U.S. Environmental Science Services Administration,
1969-1972)
June 1969 was a relatively warm, wet month with no days of
strong winds (Tables V,VI).
July and August were dry; four days of
strong winds occurred in July.
Although the first storms of 1969-70 occurred in September,
earlier than in the two other years, the winter of 1969-70 was less
stormy than the winters of 1970-71 and 1971-72 (Table VII).
September 1969 was average in precipitation and wind.
October,
November and December in 1969 were less stormy than in the two
other years.
January 1969 was average among the years in number of
storms and wind strength.
Major storms occurred on 5-6 Nov., 10-12
Dec., and 17-19 Jan. in 1969-70.
February and March 1970 were
relatively dry, calm and storm free. Storms resumed in April 1970,
arid air temperatures were approximately 2°C below normal in that
month.
Spring storms ceased by May.
June-August 1970 were very
dry and storm free, although strong north winds occurred frequently
in June.
44
The winter months of 1970-71 were much stormier than those of
1969-70, although no storms occurred in September 1970 (Table VII).
Oct. 1970 - Jan. 1971 were stormier months than in 1969-70.
Major
storms occurred on 20-24 Oct. 1970, 22-24 Nov. 1970, 1-7, 14-16,
and 27-30 Dec. 1970 and 15-18 Jan. 1971.
February 1971 was average
in the number of storms although much stormier than in 1970.
March
in 1970 was much stormier than in both of the other years, with
major storms on the 9th - 12th and 25th - 30th.
were 1.5-2.5°C below normal in March 1971.
in precipitation and number of storms.
Air temperatures
April 1971 was average
May, July, and August were
dry and storm free, but June was relatively wet with two short
storms and several days of strong north winds.
Air temperatures
were 1-2°C below normal in June and July 1971.
The winter of 1971-72 was more similar to that of 1970-71 than
1969-70.
September 1971 was wetter, but not more stormy than in
other years.
October, November and December 1971 were very stormy.
Major storms occurred on 18-19 October, 23-28 November and 11-14
December.
Storms and rain continued through April 1972, although
March 1972 was not as stormy as in 1971.
By May, storms had ceased
and relatively calm dry weather prevailed through August 1972.
Wind Speed and Direction
During June-August 1969, strong upwelling was favored by north
winds for only one month, an unusually short time (Fig. 21).
were relatively weak and primarily onshore in June 1969.
Winds
Strong
45
north winds developed in and persisted through July.
Winds were
weak in August and early September.
Strong southwest winds characteristic of winter storms were
rare in the winter of 1969-70 (Fig. 21a, Peterson and Miller,
1977).
Winds were weak in September, and strong but from an
unusual direction (east) in October and November 1969.
1969-early March 1970, south winds prevailed.
predominated during April
,
In December
Eastward winds
with short periods of southward winds.
The summer period from May through mid-August 1970 was one of
consistent upwelling, indicated by persistent, strong southward
winds.
Winds were weak and variable in August 1970 and the first
two months, September-October, of 1970-71.
A southwest wind regime typical of winter storms of the Oregon
coast existed in November 1970 to mid-April 1971, except for
variable and eastward winds in February (Fig. 21b).
From mid-April
to mid-August 1971, winds tended toward the southeast and were
unusually weak.
No strong, purely southward winds were recorded
during the summer of 1971, unlike the other years, except in July.
Weak winds caused reduced upwelling in 1970-71, relative to the
other years.
September 1971 - August 1972 was a year of both well developed
winter storms and strong summer upwelling.
Although winds were
weak and variable in direction in September-November 1971, strong
south and southwest winds indicative of winter storms began in
mid-November and continued through mid-April 1972 (Fig. 21c).
In
mid-April 1972, winds reversed direction, blowing first toward the
east and then intermittently toward the southeast in May.
Strong
southward and southeastward winds, conducive to upwelling, were
recorded from May through early September 1972, with occasional
reversals in direction.
Upwelling Indices
Positive coastal divergence index (CDI) values (Fig. 22) and
negative offshore divergence index (ODI) values (Fig. 23) were
recorded from late April through mid-September 1969, indicating
nearshore upwelling with offshore submergence of upwelled water
(Bakun and Parrish, 1980).
There were 16 weeks when the CDI was
greater than 25 m3/sec/100 m of coastline (an arbitrary estimate of
upwelling strength), fewer than in the summer of 1970 or 1972.
Onshore transport on surface water from mid-September 1969 to
mid-March 1970 was indicated by negative CDI values (Fig. 22).
Positive ODI values in October 1969-February 1970 (Fig. 23)
indicated offshore upwelling and onshore surface water transport.
This circulation pattern was disrupted less often by storms in the
winter of 1969-70 than in the other two years.
Positive CDI
values, indicating upwelling, and negative ODI values, indicating
offshore submergence of upwelled water, were recorded in
March-August 1971.
There were 21 weeks during 1970 in which the
CDI was greater than 25 m3/sec/100 m of coastline, more than in any
other year.
in 1970.
The most persistent upwelling of any summer occurred
47
Circulation patterns were more often disrupted in the autumn
and winter of 1970-71 than 1969-70.
Transport was weak, with CDI
values near zero, in September and early October 1970 (Fig. 22).
Negative CDI values indicated onshore transport from mid-October
1970 through January 1971, while ODI values switched from positive
to negative at the end of December 1970.
Both indices were usually
near zero in February-April 1971, indicating weak surface water
transport, although negative CDI's suggested that onshore transport
occurred in early February and early March.
Positive CDI values,
indicating upwelling, did not appear until mid-April 1971, later
than in 1970, and persisted through August.
001 values decreased
to zero more often in the sumer of 1971 than in the other two
years.
There were only 16 weeks of 1971 in which the CDI was
greater than 25 m3/sec/100 m of coastline, which suggested reduced
upwelling relative to the other years.
Relaxation of upwelling
occurred in early May, mid-June and late August 1971.
Zonal circulation patterns were weakly developed in October
1971 through January 1972, with CDI and 001 values frequently near
zero (Figs. 22,23).
Negative CDI values indicated well developed
onshore transport in February and mid-March 1972.
CDI values were
positive and ODI values negative from mid-April through August
1972.
There were 20 weeks during 1972 when CDI values were greater
than 25 m3/sec/100 m of coastline, which suggested strong upwelling
in the summer of 1972.
2EI
Surface Water Temperatures
Surface temperatures were initially warm (12.6-14.6°C; Table
VIII) in June 1969, but dropped by 5-6° in July, during an
upwelling event.
Warming occurred in July-early September 1969,
with the greatest increase at 18 km.
Winter temperatures were stable and relatively warm in 1969-70
compared to the other years (Table VIII).
From October through
November 1969, temperatures fluctuated between 11-12.5°C, 1-2.5°C
above the modal temperature of 10°C (Pattullo and Denner, 1965).
From January through April 1970, sea surface temperatures rose in a
gradient of 1 to 3°C going offshore.
Upwelling was indicated by a
decrease to 8.5°C inshore and 7.5°C offshore on 23 June.
Temperatures rose again in July to 11-12.5°C inshore and 12-14°C
offshore. Upwelling occurred again in early August 1970.
Sea surface temperatures were extremely variable in 1970-71.
Surface temperatures dropped to 9-10°C at all stations (Table VIII)
in early September, during upwelling.
Temperatures rose by 2°C on
25 September, except at 18 km where a high temperature of 16°C was
recorded.
Nearshore warming continued in October and November,
although temperatures at 18 km decreased.
9-10.5°C began in December 1970.
Winter cooling to
From January through March 1971
temperatures fluctuated between 7.4 and 10.5°C, gradually
increasing but with periods of cooling in late January and early
February.
From March to May, surface waters warmed by 2-2.5°C with
most heating occurring offshore.
Upwelling was indicated by a
49
decrease to 8-9°C on 29 May.
Inshore incursion of Columbia River
plume water caused warming to 13-14.5°C in June.
Another decrease
occurred in July, with a low of 8.5-9.5°C on 21 July.
Extreme
warming in August, with a gradient of increasing temperature from
14°C at 2 km to 16.5°C at 18 km, was due again to Columbia River
plume water.
Fewer upwelling events, as indicated by sudden
cooling, occurred in 1971 than 1970.
Sea surface temperatures were least variable in 1971-72 (Table
VIII).
Upwelling (8.8-9.9°C) occurred in early September and
a
gradual warming of approximately 2°C occurred at all stations by 11
October.
Temperatures cooled into the winter range (8-9°C) by 7
December 1971.
From March through July at 2 km, temperatures were
all between 9.8 and 10.6°C.
At other stations, temperatures were
in or near that range except for warming (11-12°C) on 15 March at
6-18 km and June-July at 18 km.
The temperature data do not
indicate the strong upwelling suggested by the wind data and
upwelling indices for 1972, except on 5 August (8.5-9.0°C at all
stations).
This may have been due to the relatively few samples
taken in 1972, compared to 1970 and 1971.
Surface Salinities
Sea surface salinities (32.50/oo) indicated that Columbia
River plume water was present at the start of sampling, 22 June
1969 (Table IX).
In July, salinities of 32-34.7°/oo, with the
highest values nearshore, suggested an upwelling event.
50
Surface salinities at all stations in Sept.- Nov. 1969 were in
the modal range for the area annually of 33.0-33.5°/oo (Pattullo
and Denner, 1965).
They decreased to 27.6-31.3°/oo by Jan.- Feb.
1970, indicating dilution of surface waters by rainfall and coastal
stream runoff.
1970.
Few measurements were available for March-April
Salinities as great as 33.3°/oo in May indicated the first
upwelling event of 1970.
In mid and late May, the highest
salinities were inshore, with Columbia River plume water
(30.9-31.9°/oo) at 18 km.
Upwelled water (33-35°/oo) occurred
in June-August 1970, although water of 31.5-33.00/oo was found at
9-18 km on 29 July and during August.
The high surface salinities
in June-August 1970 indicated strong persistent upwelling in those
months.
Surface salinities decreased steadily in Sept.-early Dec.
1970.
No zonal pattern of dilution suggestive of Columbia River
plume water or coastal stream discharge was seen, indicating the
direct influence of precipitation.
Decreased salinities
(25.1-28.1°/oo) at the two inner stations in mid-January
indicated high discharge from coastal streams.
Dilute surface
water (29.0-32.5°/oo) at all stations in Feb.-mid May 1971
indicated persisting winter hydrographic conditions influenced by
precipitation and runoff.
At the end of May, upwelled water
(33.5-33.8°/oo) was found at all stations.
Surface salinities
were lowered by Columbia River plume water to 29.4-30.9°/oo in
early June.
Upwelled water (33.5-33.8°/oo) occurred at the three
51
inner stations during late July.
Lower salinities in August 1971
indicated relaxation of upwelling.
Surface salinities were near the modal range again in Sept.Oct. 1971, and decreased progressively from 32.5-33.4°/oo to
31.4_32.1O/oo from September through December.
taken in Jan.- Feb. 1972.
No samples were
Salinities were low (25.1-30.5°/oo) at
the inshore stations in March-early April2, indicating the
influence of coastal runoff, and very low surface salinities
(17.1-21.4°/oo) were recorded in mid-April.
Salinities gradually
increased in May and June until they reached modal values.
Upwelling caused high surface salinities at the inshore stations in
late July-early August 1972.
Bottom Salinities
The incomplete record of bottom salinity (Table X), relative
to that of surface salinity, limited the inferences that could be
drawn from these data.
Bottom salinities greater than 34°/oo at all stations in
late July 1969 indicated upwelling with high density deep water
being brought inshore.
In Jan. - March 1970, a decreasing gradient
of bottom salinity (32.8-30.2°/oo) with decreasing distance from
shore indicated dilution by rainfall and runoff, with submergence
2
1972 was
The 35.90/oo salinity recorded at 6 km on 3-4 Marc
false. Maximum surface salinities off Oregon are 33.8 /00
(Pattullo and Denner, 1965). Salinities below the halocline in the
subarctic Pacific are never much greater than 33.80/00 (Dodimead
and Pickard, 1967).
52
and mixing of surface waters nearshore.
Bottom salinities were
remarkably consistent (33.7-33.9°/oo) in May-Aug. 1970, due to
relatively strong, persistent upwelling during that year.
Decreasing bottom salinities (33.731.0'/oo) with proximity
to shore, similar to that in the winter of 1969-70, was found in
Dec. 1970-Feb. 1971.
Bottom salinities increased
(33.4-33.7°/oo) in early March as if winter conditions were
replaced by upwelling, but they decreased (32.4-33.40/oo) by
mid-March.
The bottom salinity structure was very unstable in
May-Aug. 1971, compared to 1970.
Salinities of less than
33.50/00 were recorded in mid-May, mid and late June and late
August 1971, indicating mixing and disruption of upwelling by
storms.
Bottom salinities of 32.2-33.5°/oo indicated a return to
winter hydrographic conditions in Dec. 1971.
Low bottom salinities
(31.2-32.6°/oo) were found at all stations when sampling resumed
in March 1972.
Salinities increased in March-May 1972.
Bottom
salinities in June-Aug. 1972 were high (32.9-33.9°/oo) and
stable, which indicated persistent upwelling conditions more
similar to those of the summer in 1970 than 1971.
53
DISCUSSION
Comparisons with Previous Studies of Larval Fish Assemblages Off
Oregon
The taxa found in this study were the same as those taken by
Richardson and Pearcy (1977), with the exception of a few rare
species.
Most were members of their coastal assemblage, and
members of their offshore assemblage that were taken more than once
in this study were occasionally found nearshore by Richardson and
Pearcy (1977).
Artedius meanyi and Cyclopteridae Type 1 were
dominant taxa in this study, but not in Richardson and Pearcy
(1977).
They found Hemilepidotus spinosus and Cottus asper to be
dominants in the coastal assemblage during 1971 and 1972.
The
seasonal cycle of abundance described in their paper for 1971 and
1972 was similar to that found in this study, with peaks of
abundance in late winter and early summer and a period of low
abundance in late summer.
The geographic assemblages discussed by Richardson et al.
(1980) included members of the winter and spring-summer
species-groups of this study, because their samples were taken in
the transitional months of March and April.
Several species not
taken in great numbers during this study were abundant nearshore in
1972-75, including Anoplarchus spp., Leptocottus armatus, Pholis
spp. and Radulinus asprellus (Richardson et al., 1980).
54
The Relationship of Environmental Factors to Annual Differences in
Occurrences of Taxa in the Winter Species-Groups
Two factors influence the variability in larval fish
occurrences.
First, variation in spawning season (Qasim, 1955;
Johannes, 1978; Scott, 1979) and numbers of eggs produced by the
parent stock (Gulland, 1965; Cushing and Harris, 1973) determine
when and how many larvae are introduced into the plankton.
Second,
survival, transport, and duration in the plankton of the early life
history stages determine when and how many larvae will be available
from the eggs initially produced by the spawning stock.
No
information was available on spawning stock sizes for this study.
For that reason, and because larval survival is considered the most
important factor of the two in determining annual variability of
larval abundance from a single stock (Gulland, 1965; Cushing and
Harris, 1973; Hunter, 1976), effects of spawning stock size will
not be discussed further.
In each year, members of winter species-groups appeared in
late November or December after a series of winter storms, when
salinities indicated dilution and temperatures indicated cooling.
The seasonal regularity of their appearance also suggested that a
regular annual factor, such as photoperiod, may have influenced the
spawning time of the winter spawning fishes (Scott, 1979).
The
slight variability in time of first capture of winter species was
closely related to the first large series of storms in each year
(Table VII) and the transition to winter hydrographic conditions
(Tables VIII and IX).
55
Relatively stable winter oceanographic conditions, without
frequent disruption by storms favored the retention and abundance
of larvae of winter spawners in 1969-70.
The winter group was only
distinct in 1969-70 (Table II), although the absence of the group
in 1971-72 may have been due to the sampling gap in Jan.- Feb.
1972.
Also, Sebastes spp. and large (>17 mm) Parophrys vetulus
larvae were more abundant in 1969-70 than other years.
There were
fewer storms in Dec. 1969 - Feb. 1970 than in those months in the
other years (Table VII).
Sea surface temperatures in Dec. 1969
Jan. 1970 were 1-2°C warmer than in 1970-71.
-
Upwelling indices
indicated increased onshore convergence in the winter of 1969-70
relative to the other years (Figs. 22 and 23).
In 1969-70, species
from the winter group persisted until salinities indicated
alteration of the hydrographic regime from dilute warm conditions
to the spring and summer upwelling regime.
In the other two years,
members of the winter groups were rare long before the hydrographic
change, with the exception of Parophrys vetulus in 1970-71.
Larval fish food items may have been more abundant in the
winter of 1969-70 than in the winters of 1970-71 and 1971-72.
Nauplii of copepods other than those of Calanus marshallae were
most abundant in the winter of 1969-70 and other known larval fish
prey (Arthur, 1976; Hunter 1981), including Calanus naupili,
pteropods, Oikopleura, barnacle nauplii, adult Oithona and adult
Paracalanus, were also very abundant in the winter of 1969-70
(Peterson and Miller, 1976).
Copepod early life history stages are
56
the most important prey item for most species of larval fish
(Hunter, 1981).
Predation by chaetognaths may have contributed to the low
abundances of fish larvae in 1970-71.
Although chaetognaths were
not as numerous in the winter as the summer, chaetognaths were more
abundant in the winter on 1970-71 than in the other two winters
(Peterson and Miller, 1976).
Ctenophores and medusae were not
common in the winter of any year (Peterson and Miller, 1976),
suggesting that predation may not be as important a control on
numbers of winter-group fish larvae as those of the summer groups.
The abundances of predators other than ctenophores, medusae and
chaetognaths were not reported by Peterson and Miller (1975, 1976,
1977), but Pearcy (1976) found nearshore abundances of planktonic
carnivores off Oregon, including chaetognaths, medusae, amphipods
and shrimps, to be significantly lower in winter than summer.
Parophrys vetulus (English sole)
Parophrys vetulus larvae were abundant at all stations.
They
have previously been reported from 2 to 74 km from shore
(Richardson and Pearcy, 1977), with most taken shoreward of the 200
m isobath and highest concentrations within 18 km of the coast
(Laroche and Richardson, 1979).
Kruse and Tyler (1983) suggested that English sole are capable
of spawning throughout the year, but spawn when bottom temperatures
are above 7.8°C (during onshore convergence) and increase
gradually, usually during 1-3 months in September through April.
57
Data from the present study was used in construction of their model
and is congruent with it.
Parophrys larvae appeared in the fall or
winter of each year in 1969-72 after the transition to onshore
surface water transport, as indicated by upwelling indices (Figs.
22 and 23).
Larval Parophrys were first collected three weeks to
two months after this transition, although the lengths of the lags
may have been partially due to sampling frequency.
An autumn
spawning peak of English sole was well developed only in 1969, the
only year in which onshore convergence was seen in September and
October.
Relative year-class strengths of English sole from 1969-72, as
estimated from commercial harvests (R.L. Demory, ODFW, pers. comm.:
see METHODS) rank as 1969-70=1, 1971-72=2, and 1970-71=3.
The mean
abundance of Parophrys larvae was greatest in 1970-71 but large
(>17 mm) larvae were only taken in 1969-70.
Large numbers (mean
109.0/10 m2) of small Parophrys larvae were taken in Feb. 1971.
In
1972, although Jan.- Feb. were not sampled, the capture of only one
larva in March indicated that abundances of Parophrys were much
lower in the winter of 1971-72 than in the other years.
English
sole larvae have a pelagic life of 8-10 weeks (Laroche et al.,
1982).
Larvae hatched in Jan.- Feb. 1972 should have been captured
in March and April if they were numerous and their survival good.
The year of greatest larval english sole abundance, 1970-71, did
not produce the largest cohort of adult fish, and the year of
lowest larval abundance, 1971-72, produced the second largest
year-class of the three years.
The discrepancies between relative
annual larval and adult abundances, also found for Isopsetta
isolepis, could have several explanations.
Estimates of relative
abundance of larvae should be appropriate between years, given
consistency of sampling.
Estimates of recruits to the fishery and
adult numbers were taken from research cruises for Isopsetta and
commercial catches for Parophrys.
Hayman et al. (1980)
demonstrated that catch per unit effort is a valid estimator of
year-class strengths for English sole.
offer explanations for the discrepancy.
Biological reasons could
Survival at sizes larger
than the planktonic larval stage may determine year-class success.
For example, mortality after the pelagic stage might determine
year-class strengths, rather than a critical period during the
larval stage.
Steele and Edwards (1970) suggested that predation
and competition for food in the more spatially limited benthic
environment might determine year-class strengths in flatfish during
transformation to benthic juvenile stages.
Longer term correlative
studies of larval survival and resulting cohort strength, and
studies of mortality during transformation would be useful to our
increased understanding of year-class strength formation in English
sole.
The factors that contributed to increased survival of
Parophrys larvae in 1969-70 relative to the other years were those
that have been discussed previously of taxa in the winter species
group (pp. 54-56).
In particular, fewer storms in Dec. 1969 - Feb.
1970 may have allowed stable upper ocean conditions to form, in
which food organisms could have been concentrated and successful
feeding by fish larvae aided (Lasker, 1981a,b).
More food
organisms may have been available inshore (Peterson and Miller,
1976) because of greater onshore convergence (Figs. 22 and 23),
less offshore loss and perhaps because of increased water
temperatures (Table VIII) due in part to the insurgence of
southerly coastal water, including a zooplankton fauna of more
southern affinities (Peterson and Miller, 1976).
The feeding
ecology of larval English sole, with implications for survival of
the larvae, is currently being investigated (Gadomski, in prep.).
Laroche and Richardson (1979) suggested that light variable
winds and other factors related to reduced numbers of storms should
favor high abundances and good survival of larval Parophrys.
The
origin of the strongest adult year-class in the winter of reduced
storms in this study supports their hypothesis.
However, the
strongest, most persistent winter winds of 1969-72 occurred in Nov.
1971 - March 1972 (Fig. 21), when reduced larval abundances were
associated with an intermediate year-class.
The positive effect of
decreased onshore drift of surface water on survival of Parophrys
larvae (Laroche and Richardson, 1979) was not consistent with
larval abundances and upwelling indices observed in this study.
The Parophrys year-class from 1982-83 may prove useful in
evaluating the effects of these influences. The winter of 1982-83
Interestingly for
was stormy, but water temperatures were warm.
comparison with 1970-71, transforming Symphurus atricauda, a fish
species of southern origin previously found in Yaquina Bay only
during 1970 and 1971 (Krygier et al., 1973; C.E. Bond, OSU, pers.
comm.) was collected again in March-April 1983 (pers. obs.).
Parophrys larvae were rarest when onshore drift was weakest, in
1971-72 (Fig. 22 and 23).
when survival was greatest.
Onshore drift was strongest in 1969-70
A similar discrepancy existed for the
strong year-class and increased onshore drift in 1961 (Laroche and
Richardson, 1979).
I suggest that Parophrys year-classes are stronger from years
when larvae are abundant in both fall and spring, given
accompanying conditions of weak or infrequent storms when larvae
are present, than from years with only a spring peak.
Between 1969
and 1972, the strongest year-class came from a year in which larvae
were abundant both in Nov.- Dec. and Feb.- March, and the weakest
from a year in which larvae were even more abundant but only in
Feb. - March.
Parophrys larvae present in March-April would be
likely to encounter upwelling conditions that seem to be
Laroche and
detrimental to larval English sole survival.
Richardson (1979) sampled only in March-April
larvae to be most abundant then.
,
assuming Parophrys
Their estimates of larval age
indicated that larvae hatched in November would still be pelagic
then.
Later studies (Laroche et al., 1982; Rosenberg and Laroche,
1982) have shown that English sole are pelagic for only 8-10 weeks,
and that Parophrys hatched in December would not be taken
planktonically during March and April.
Hayman and Tyler (1980) suggested that the factors most
strongly related to large Parophrys year-classes were cold autumn
sea surface temperatures, increased autumn barometric pressure and
persistent autumnal upwelling.
They suggested that persistent
61
upwelling acted to delay spawning until larvae would be placed in
food rich water or eggs would be of better quality due to better
condition of late spawning females.
However, their analysis is not
good at predicting very strong year-classes.
Hayman (1978) assumed
that cohort strengths were determined solely during the pelagic
larval stage, and that mortality at transformation would not be
important.
The results of this study suggest that the latter
possibility should be investigated.
Sebastes spp. (rockfishes)
The distribution of larval Sebastes indicated that they may
have been advected into the study area from offshore, except that
small rockfish taken in large numbers at single stations on single
dates may have been products of recent parturition.
While various
species of rockfish may have been giving birth in Oregon shelf
waters in all months, most newly born Sebastes were taken in winter
months, during the winter hydrographic regime.
Sebastes larvae were most abundant in the winter of 1969-70.
Their abundance may have been influenced by the same factors that
influenced the winter-group species discussed previously.
However,
the possibility that 36 Sebastes species could have contributed to
the catch of rockfish larvae made interpretation of their annual
variability impossible.
Ammodytes hexapterus (Pacific sand lance)
Sand lance larvae were patchily distributed, usually found in
abundance at isolated stations on single dates.
They were taken
seaward of 18 km only once by Richardson and Pearcy (1977).
In the
Atlantic, they were found dispersed over the entire continental
shelf (Richards and Kendall, 1973).
In this study, Ammodytes
larvae were taken during less than two months in each year.
In
contrast, sand lance larvae in other oceans have long seasons of
occurrence in Nov.- March (Richards and Kendall, 1973).
Ammodytes larvae were more numerous in 1969-70 than 1970-71,
but more large (?7 mm) larvae were taken in 1971.
In 70 cm bongo
net samples, Ammodytes larvae were 12.2 times more abundant in
1970-71 than 1971-72 (Richardson and Pearcy, 1977).
This may have
been an artifact of the lack of samples in Jan.- Feb. 1972, months
in which they would have been expected to be abundant.
Sand lance
larvae occurred in each year within the winter hydrographic regime
of convergence, dilution of surface waters and south or southwest
winds, but no specific hydrographic factors were found to be
directly related to their occurrences.
Factors influencing annual
larval Ammodytes abundances were those discussed for taxa in the
winter species-group (pp. 54-56).
63
The Relationship of Environmental Factors to Annual Differences in
Occurrences of Taxa in the Spring and Summer Species-Groups
In each year, taxa in the spring and summer species-groups
(Table II; 1969-70 = 3-5, 1970-71 = 3-4, 1971-72 = 1-3) appeared
after winds shifted in direction to north or west (Fig. 21) and
upwelling began (Figs. 22 and 23).
In 1969-70 and 1971-72, members
of the spring-summer groups first appeared in April.
First
appearance of those taxa in 1971-72 is tentatively assumed because
winter species-group larvae were present in March and spring-summer
group larvae were found in April, even though no samples were taken
in Jan.- Feb. 1972.
In 1970-71, members of the spring-summer
groups appeared earlier, in February.
Larvae taken in February
were spring-summer species abundant in May and June, but rare in
both January and March 1971.
The anomalous condition of dissimilar
species groups occurring in February and March 1971 was caused by
the absence of a well defined winter species-group, the early
appearance of spring-summer species in February and the rarity of
spring-summer species (e.g. Artedius harringtoni, Fig. 14; A.
fenestralis, Fig. 19; Platichthys stellatus, Fig. 16; Psettichthy
melanostictus, Fig. 11) in March of that year.
Several species (e.g. Osmeridae, Isopsetta isolepis,
Microgadus proximus) from the spring-summer groups were most
abundant in 1970-71, especially May-June, and least abundant in
1969-70.
High abundances of those species persisted through a
longer period at 2-9 km in the summer of 1970-71 than in the other
64
two years (App. III), indicating better production, retention or
survival of larvae in the coastal region during that year.
Factors
related to this may have been retention of coastal water during
reduced upwelling in conjunction with stable hydrographic
conditions, following the emergence of nutrient rich upwelled
water.
Highly variable winds and stormy conditions in Feb. - March
1971 followed by calm weather in April (Table VIII; Fig. 21) may
have created
conditions of nutrient mixing followed by upper mixed
layer stability conducive to larval fish survival in upwelling
regions (Lasker, 1975, 1981a,b).
Upwelling indices (Figs. 22 and
23) progressive vector diagrams (Fig. 21), sea surface temperatures
(Table VIII) and salinities (Tables IX and X) all indicated more
sporadic, weaker upwelling in 1970-71 than in the other two years.
In contrast to 1970-71, 1969-70 was a year of strong southward
winds (Fig. 21) and pronounced upwelling (Figs. 22 and 23).
Upwelling indices (Figs. 22 and 23) and strong north winds (Fig.
21) indicated strong upwelling in 1971-72, but only one upwelling
event was recorded in the temperature and salinity data from that
year.
The lack of upwelling events in the hydrographic record from
1972 may have been due to the infrequent sampling in that year.
The very low abundances of spring-summer species in 1969-70 was
associated with more frequent upwelling without the long periods of
relaxation that characterized the summer of 1970-71.
Not all members of the spring and summer species-groups were
most abundant in 1970-71.
Artedius meanyi and Psettichthys
melanostictus were most abundant in 1969-70, the year of strongest
65
upwelling.
Platichthys stellatus and Artedius harringtoni were
most abundant in 1971-72, the intermediate year.
As will be
discussed later, Psettichthys larvae occurred most often in low
temperature, high salinity water, suggesting that they were more
resistant to adverse influences of strong upwelling than other
coastal fish larvae.
The fact that different species of larval
fish in the same geographic and temporal species-groups show
obviously different responses in annual occurrence patterns to
changing environmental factors, points out the need to study larval
fish as individual species for full understanding of their biology,
rather than simply as members of species-groups.
No physical factors seemed to be related to the disappearance
of larvae in the spring-summer groups at the end of the summer.
Larvae generally became rare long before winter storms resumed and
the summer upwelling regime changed to rain and onshore transport.
Factors related to spawning cessation earlier in the summer may
have more to do with the disappearance of larvae than direct
environmental effects on those larvae.
Zooplankton abundances were lower in the summer of 1970-71,
particularly June-July, than in 1969-70 (Peterson and Miller,
1975). This, in conjunction with the highest abundances of
osmerids, Isopsetta and Microgadus in 1970-71, does not corroborate
the hypothesis that larval fish abundance and survival are
correlated with zooplankton abundances (Cushing, 1969,1975).
In
contrast to the three most dominant spring-summer taxa, two other
species, Psettichthys melanostictus and Artedius meanyi had annual
ranks of abundance in the same order as total zooplankton abundance
(1969-70>1970-71>1971-72), suggesting that abundance and survival
of larvae of those species was more closely related to total
zooplankton abundance.
Copepod nauplii, Calanus early life history
stages and Pseudocalanus, among other known larval fish prey, were
most abundant in the spring and summer of 1969-70 and least in
1971-72.
Although inferences about survival of larval fish drawn
from zooplankton abundances must be carefully made, greater
knowledge of the feeding habits of single larval fish species
should lead to an understanding of the relationship between their
survival and prey abundance (Lasker, 1978; Gadomski, in prep.).
Major problems in assessment of larval food concentrations
affecting this study were that patchiness of food organisms was not
assessed (Hunter, 1981), that most copepod early life history
stages were not quantitatively sampled by the mesh sizes used
(Arthur, 1977; Peterson and Miller, 1976) and that the prey of most
larval fish species off Oregon are unknown.
Predation may have contributed to declining abundances of fish
larvae in the late summer of each year.
Predators of larval fish
include large copepods, euphausids, hyperiid amphipods,
chaetognaths, siphonophores, medusae, ctenophores and fishes
(Hunter, 1981).
Peak summer chaetognath concentrations occurred in
June-July 1970 (mean = 6.1/m3) and June-July 1971 (mean = 6.7/me)
(Peterson and Miller, 1976), coinciding with declines in larval
fish abundance.
However, they were most numerous in May 1970 (mean
= 8.0/rn3) and 1971 (mean = 8.5/m3) when fish larvae were abundant.
67
Increased chaetognath numbers were not always associated with
declining larval fish abundance.
Ctenophores were only abundant in
May-June 1971 (mean = 6.1/rn3) and 1972 (mean
and Miller, 1976).
6.3/m3) (Peterson
May and June were the months of greatest larval
fish abundance in 1971, with numbers declining in August.
May was
the month of greatest larval fish abundance in 1972, but abundances
declined in June.
Medusae were numerous in May-Oct. of each year,
with the greatest concentrations in July-Sept. 1970 (mean
=
17.5/rn3), June-July 1971 (mean = 4.8/rn3) and late May 1972 (mean =
9.5/rn3) (Peterson and Miller, 1976).
The most abundant
scyphomedusa off the Oregon coast, Chrysaora fuscecens, is found in
its greatest concentrations and largest sizes during August, in the
period May-August (Shenker, in press).
Concentrations of Chrysaora
are low prior to June and after September.
Predation by
chaetognaths, ctenophores and medusae in June-September may have
contributed to the decline in larval fish abundance in late summer.
Alvariio (1980) found an inverse relationship between abundances of
larval Engraulis mordax and gelatinous zooplankton, suggesting that
increased numbers of predators increased mortality of larval fish.
Möller (1980) suggested that 2-5% of the standing stock of Baltic
Sea herring larvae may be eaten per day by scyphomedusae, while
Purcell (1981) suggested that as much as 28.3% of the fish larvae
in a restricted Gulf of California cove could be consumed per day
by siphonophores.
Clearly, predation on larval fish by
coelenterates can be a major source of mortality for the larvae.
In April-Sept. of each year, fish larvae were occasionally
rare or absent at 9-48 km from shore at times when surface
salinities indicated that Columbia River plume water was present
(App. III, Table IX; salinity
32/5°/oo).
However, not all
occurrences of plume water were associated with low larval
abundances.
The largest number of larvae in this study were taken
from plume water during May-June 1971 (App. III; Table IX).
gaulis mordax spawning off Oregon is associated with the
Columbia River plume and larval anchovy are most abundant in or
below plume water (Richardson, 1981), but no other larvae are
associated with the plume.
Anchovy larvae were rare in this study.
Only one occurrence (30 Aug. 1969) was associated with Columbia
River plume water and most other anchovy larvae were larger
specimens (11-22 mm) taken at 2-6 km in Dec. 1969- Feb. 1970 during
onshore advection of rain diluted water.
The stable productive
conditions in the plume hypothesized by Richardson (1981) as
conducive to anchovy spawning and larval survival may not always be
suitable for survival of coastal species-group larvae.
Temperature
and food requirements of larval Engraulis, particularly the unusual
need for small (<80 mm) particles such as Gymnodinium at first
feeding (Lasker and Smith, 1977; Hunter, 1981) may be met in the
Columbia River plume.
The hydrographic stability and high
productivity necessary for survival of larval anchovy (Lasker,
1975, 1981a,b) may exist in the biomass cores found at the
nearshore boundary of the plume during relaxed upwelling (Small and
Menzies, 1981).
However, plume water at 2-18 km off Newport had
been subject to cooling and mixing with more saline water as it
travelled south (Pattullo and Denner, 1965; Barnes, et al., 1972;
this study) and was not always good habitat for coastal species of
fish larvae.
Even anchovy larvae do not often accompany plume
water to nearshore areas (Richardson, 1981).
Osmeridae (smelts)
The five species of osmerids off Oregon spawn in rivers,
coastal streams or on beaches (Hart, 1973), explaining their
nearshore larval distribution.
Length frequencies (Fig. 8)
indicate at least two smelt spawning peaks, in winter (Dec.- March)
and spring (May-June), as suggested by Richardson and Pearcy
(1977).
A few small (<10 mm) osmerjds were found in late summer
and early fall, suggesting that various smelt species spawn
throughout the year.
The largest influx of smelt larvae, during
May-July 1970 and 1971, was probably a single species.
Spawning
seasonality and environmental factors influencing the abundance of
single species of smelt larvae could not be assessed because
species were not identified.
Smelt with fins formed would have
been good avoiders of 20 cm bongo nets, biasing estimates of
abundances of transforming osmerids.
Osmerid larvae that were present in Dec.- March followed the
seasonal abundance pattern for the winter species-group (pp.
54-56), being most abundant in 1969-70 and least in 1970-71.
70
Smelt larvae were the major component of the spring-summer
species-groups and followed the pattern for those groups (pp.
63-67).
Smelt found in the summer showed no strong relationship
with upwelling.
The largest numbers of smelt, in May-June 1971 and
May 1972, were associated with summer storms and Columbia River
plume water (App. III, Table IX).
Wave action produced by storms
facilitates larval emergence from the hatching substrate in one
osmerid, Mallotus villosus, and large concentrations of larval
Mallotus are found after storms (Frank and Leggett, 1981).
Similar
storm-induced emergence may occur for species of smelt spawning in
Oregon waters.
Onshore transport, nearshore retention and
association with the core of high productivity at the shoreward
edge of the plume (Small and Menzies, 1981) may have been
occasionally conducive to high abundances of osmerid larvae.
However, smelt larvae were not abundant in plume water in months
other than May-June.
The influx of smelt larvae in plume water
during May would most reasonably be expected to be due to a species
spawning in the Columbia River.
Thaleichthys pacificus
(eulachon), the major species spawning in the Columbia,
spawns in
Feb.- March (Wydoski and Whitney, 1979). The latest eulachon
spawning runs occur in the Sandy River Tributary.
In 1969-72, the
only Sandy River run was recorded on 23 March 1971, with none in
the other years (Carol Moon, ODFW, pers. comm.).
after 30-40 days (Hart, 1973).
The eggs hatch
It is possible that larvae of the
sizes found in May and June 1971 could have resulted from the 23
March Sandy River spawn, and that they were drifting in the
71
Columbia River plume.
However, it is also possible that larvae of
another species could have composed this large peak in abundance.
Isopsetta isolepis (butter sole)
The seasonal distribution of Isopsetta isolepis larvae was
like that found by Richardson and Pearcy (1977).
They found butter
sole spawning in Feb.- May, but Richardson et al. (1980) found
small larvae in Jan.- May and October of various years.
Although
Isopsetta larvae are most abundant in the spring, usually May
(Richardson and Pearcy, 1977; Richardson et al., 1980; this study),
butter sole are capable of spawning from mid-autumn through late
spring.
Isopsetta larvae of all sizes were most abundant in 1970-71
and least in 1969-70.
From this information, one would conclude
that the resulting ranks of year-class strengths would be
1970-71>1971-72>1969-70.
However, preliminary data from the recent
contribution of different year-classes to research survey catches
of butter sole off Oregon and Washington in 1973 and 1975 indicated
that the actual year-class ranks were 1971-72>1969-70>1970-71 (Fig.
24; Robert Demory, ODFW, pers. comm.).
The highest annual
abundance of larvae produced the lowest relative number of adults.
Reasons for this discrepancy were discussed for Parophrys vetulus
(pp. 57-58), although it should be noted that the estimates of
year-class strengths for Isopsetta are more tentative than for
Parophrys.
72
Larval Isopsetta isolepis abundances were influenced by the
factors affecting osmerids and Microgadus proximus, discussed for
the spring-summer groups in general (pp. 63-67).
Factors present
in 1971-72, when the strongest year-class was produced, were
delayed upwelling (Fig. 22) with persistence of surface water
dilution by rainfall and runoff (Table IX) and followed by
persistent, relatively strong upwelling from May through August
(Fig. 22).
Sea surface temperatures were relatively cool in the
spring and summer of 1972 (Table VIII).
However, environmental
conditions after the end of sampling in 1972 may have been more
influential on year-class strength, enhancing survival of larger
larvae or juveniles.
Isopsetta larval abundances did not show an immediate
relationship to any environmental variable.
They were greatest
just prior to and during upwelling events early in the year.
Butter sole larvae were scarce or absent after persistent upwelling
began in June and July.
They were most abundant just prior to and
during upwelling in May 1971, when they were apparently retained at
6-9 km from shore until Columbia River plume water moved over the
region.
Psettichthys melanostictus (sand sole)
Psettichthys melanostictus larvae were spatially and
temporally patchy in occurrence, and were not retained inshore for
long periods.
Little information exists about sand sole spawning
habitat, except that they spawn in coastal waters (Wang, 1981).
73
Psettichthys spawned in late winter-spring, late summer and
autumn, with peak spawning in late winter-spring (Fig. 11).
Multiple spawning times occurred in 1968-69 and 1970-71 (Fig. 11).
Sand sole spawn in Jan. - March in Puget Sound (Hickman, 1959) and
Jan.- July off Canada (Hart, 1973).
Richardson and Pearcy (1977)
found small larvae (<8 mm?) off Oregon in all months of 1971 except
July, Aug., and Dec., but only found larvae smaller than 5 mm in
Jan., Feb., May and Sept.- Nov.
Sand sole apparently cease
spawning during summer.
Psettichthys larvae were most abundant (mean = 3.0/10 m2) in
1969-70, in contrast to other dominant members of the spring-summer
groups.
They were least abundant in 1970-71 (mean
1.3/10 m2).
Two abundance peaks occurred in that year; one in May-July and one
in autumn.
The year when sand sole larvae were most abundant,
1969-70, was the year of strongest, most persistent upwelling (fig.
22) and highest zooplankton abundances (Peterson and Miller, 1975).
The year of next highest abundance, 1971-72, was also a year of
strong upwelling.
Psettichthys larvae occurred most often and in
greatest concentrations in water with surface salinities and
temperatures characteristic of upwelling.
Apparently, upwelling
was more favorable to high abundances of sand sole larvae than to
larvae of most other dominant coastal fish species off Oregon.
Offshore transport during upwelling may be less detrimental to
Psettichthys larvae than to other coastal larvae because of
a
prolonged larval life and greater ability to sustain drift, which
might allow sand sole to return to juvenile habitats.
Psettfchthys
74
remain pelagic and transform at larger sizes than most Oregon
coastal flatfishes (Orcutt, 1950; Hickman, 1959; Richardson et al,
1980), although they are smaller than Glyptocephalus zachirus or
Microstomus pacificus larvae at similar stages of development
(Ahistrom and Moser, 1975; Pearcy et al., 1977).
Nothing is known
about the duration of larval life in the sand sole, but larval
flatfish size is proportional to the duration of the larval stage
Flatfish species which transform at larger sizes
(Moser, 1981).
have extended larval lives, and may increase the probability of
successfully encountering suitable juvenile habitat following
larval drift by withholding transformation (Futch, 1977; Pearcy et
al., 1977; Moser, 1981).
Microgadus proximus (Pacific tomcod)
Microgadus proximus larvae were most abundant 6-9 km offshore,
indicating shelf spawning.
Richardson and Pearcy (1977) found a
similar distribution pattern with only two occurrences seaward of
18 km.
Retention at midshelf may be very important for larval
tomcod survival.
off Oregon.
Microgadus spawn in mid-winter through mid-spring
Two abundance peaks of newly hatched larval Microgadus
were found in each year.
The gap between the spawning peaks was
not associated with any recognizable environmental
factor, and
occurred in different months in each year; May-June 1970, April
1971 and early March 1972.
Environmental factors influencing larval tomcod abundance were
those that influenced abundances of Isopsetta isolepis (pp. 63-67).
75
Consistent, well-defined relationships between hydrography and
larval Microgadus abundances were not found.
Tomcod larvae were
abundant during certain early strong upwelling events but were not
found once intensive upwelling began in mid-summer of each year.
The greatest concentrations of Microgadus larvae were found in late
May 1971 during an upwelling event.
Artedius harringtoni (scalyhead sculpin)
The shallow-shelf distribution of Artedius harringtoni larvae
reflected the distribution of adults in shallow-shelf waters
(Hart, 1973).
Retention of scalyhead sculpin larvae nearshore may
have been important to their survival.
Their spawning season
varied from mid-winter through mid-summer off Oregon (Fig. 14).
Scalyhead sculpin was one of the spring-summer species that
appeared early in winter 1970-71 (Fig. 14), when water temperatures
were warmer (Table VIII), winds more variable (Fig. 21) and onshore
convergence weaker and less steady (Figs. 22 and 23) than in
196 9-70.
Larval A. harringtoni were most abundant in 1971-72 (mean
2.4/ 10 m2) and least in 1969-70 (mean
0.6/10 m2).
Environmental
factors that influenced the abundance of larval A,. harringtoni
apparently differed from those influencing species discussed
previously, but obvious consistent annual relationships were not
found for A. harringtoni.
Larval scalyhead sculpins were rare or
absent when strong local upwelling cccurred, except in August 1972
(Tables VIII-X).
76
Platichthys stellatus (starry flounder)
Platichthys stellatus usually spawn at depths less than 30 m,
probably near estuaries (Orcutt, 1950), explaining their larval
occurrence at inshore stations.
spring off Oregon (Fig. 16).
They spawn in late winter-early
Richardson and Pearcy (1977) found 3
mm Platichthys in March-May off Oregon, while Orcutt (1950)
suggested that starry flounder spawned in Nov.- Feb., with a peak
in Dec.- Jan., in Monterey Bay.
Starry flounder of all sizes were rare in 1969-70 (mean
0.1/10 m2) and most abundant in 1971-72 (mean
Artedius harringtoni.
=
2.7/10 m2), as were
The earlier end of dilution of surface
waters due to decreased rainfall and runoff in 1969-70 may have
been associated with decreased larval Platichth,ys abundance.
Starry flounder larvae were found primarily in water with
temperatures and salinities characteristic of dilution.
They were
taken only three times in upwelled water and were abundant (>10/10
m2) on only one of those occasions.
Lyopsetta exilis (slender sole)
The distribution of Lyopsetta exilis larvae was patchy,
because few specimens were taken (Fig. 17) and because the center
of abundance of Lyopsetta larvae is seaward of 18 km (Richardson
and Pearcy, 1977).
Inshore occurrences of slender sole larvae may
have been due to onshore advection.
Small (<6 mm) larvae were
77
found in March-June (Fig. 17), the same spawning months reported by
Richardson and Pearcy (1977).
No annual differences in larval abundances were found for
Lyopsetta, perhaps because their major geographic area of
occurrence was not included in this study.
Slender sole larvae
were included in the offshore or transitional larval fish groups
(Richardson and Pearcy, 1977; Richardson et al., 1980), with most
specimens found seaward of 28 km.
Lyopsetta larvae were usually
taken when upwelling indices indicated active upwelling (Figs. 22
and 23) and were most abundant when surface and bottom salinities
were high (33-34°/oo) during active local upwelling.
Artedius meanyi (Puget Sound sculpin)
Artedius meanyi spawn in late winter-spring off Oregon (Fig.
18).
Larval Puget Sound sculpin were most abundant in 1969-70
(mean = 0.7/10 m2) and least in 1971-72 (mean = 0.2/10 m2).
High
abundances in July-Aug. 1969 indicated that 1968-69 was also a
better year for larval A. meanyi. than 1970-71 or 1971-72.
They
were unusual as a member of the spring-summer groups because they
did not appear earlier in 1970-71 than in 1969-70, and because they
were not abundant in the Columbia River plume water that contained
large numbers of other species in June 1971.
Puget Sound sculpiri
larvae were most abundant just prior to and during upwelling events
in late spring and early summer.
Their greatest abundance was in
the year of strong, persistent upwelling.
Environmental factors
jul
conducive to high abundances and good survival of Artedius meanyi
larvae were similar to those affecting Psettichthys melanostictus.
Artedius fenestralis (padded sculpin) and
Cyclopteridae Type 1 (snailfish)
These two taxa did not differ in abundance among years.
Spawning of Artedius fenestralis occurred primarily in winter (Fig.
19), as previously reported (Hart, 1973), with occasional spawning
in the summer.
Comparisons of the Annual Variability in Occurrences of Larval Fish
Off Oregon to That in Other Groups of Zooplankton
The pattern of annual variability in holoplankton abundance
was similar to that of larval fish in the winter and dissimilar in
the spring and summer.
Plankton concentrations were greater in the
winter of 1969-70 than in the two other years and more taxa of
southern affinities were taken in 1969-70 (Peterson and Miller,
1977).
Possible causes included increased northward surface water
transport, elevated sea surface temperatures (1-2°C) and reduced
storm frequency in the winter of 1969-70 (Peterson and Miller,
1977).
During the summer upwelling season, April-Sept., plankton
abundances were lowest in 1971 (Peterson and Miller, 1975).
Of the
larval fish, only Psettichthys melanostictus and Artedius rneanyi
had this pattern.
Zooplankton taxa which were most abundant in
1971 were offshore species, while neritic species had reduced
79
abundances (Peterson and Miller, 1975).
Possible causes included
reduced upwelling, increased storm frequency and increased onshore
advection in 1971 (Peterson and Mifler, 1975).
Apparently,
nearshore retention favored the abundance of osmerid, Microgadus
and Isopsetta larvae, but not neritic zooplankton.
The abundances
of many fish larvae of the spring-summer groups are not closely
matched to total zooplankton abundance, both on a seasonal and
inter-annual basis, with the notable exceptions of Psettichthys
melanostictus and Artedius meanyi.
Better concurrent sampling of
larval fish and their prey will be necessary to investigate the
relationship of zooplankton and ichthyopiankton abundance in the
region.
As with holoplankton, the annual variability in occurrences of
crab larvae was similar to that of fish larvae in winter, and
dissimilar in spring and summer.
Abundances of large larvae of a
crab present in the plankton during winter, Cancer magister
(Dungeness crab), were low in 1970-71 (Lough, 1975) when fish
larvae of the winter species group also were rare.
Causes may have
been cool water temperatures, low salinities and reduced food
abundances in winter 1970-71 (Lough, 1975).
Most other crab larvae
off Oregon are similar to spring-summer group fish larvae,
occurring in Feb. - July with a peak in abundance in May-June
(Lough, 1975).
In 1971, larvae of other crab species appeared
later than usual (Lough, 1975), in contrast to the early appearance
of spring-summer group fish larvae in that year.
The different
time of appearance of crab and fish larvae in 1971 suggested that
spawning of crabs and fishes off Oregon was controlled by different
physical factors.
Also, crab larvae had a second peak of abundance
in Sept.- Oct., when fish larvae were least abundant, suggesting
major differences in spawning responses of adults and early life
history strategies of crabs and fishes off Oregon.
Survival of pink shrimp larvae (Pandulus jordani), a species
found in the plankton during spring and summer, was estimated to be
greater in 1972 than 1971 (Rothlisberg, 1975; Rothlisberg and
Miller, in press).
Causes may have been cold water temperatures
and stronger upwelling in 1972 (Rothlisberg, 1975; Rothlisberg and
Miller, in press), in contrast to the adverse relationship of
upwelling strength to larval fish abundance for most coastal
species except Psettichthys melanostictus and Artedius meanyi.
Pink shrimp are an offshore species, most numerous 32-40 km
offshore (Rothlisberg, 1975; Rothlisberg and Miller, in press).
Therefore, life history strategies and survival
responses to
environmental conditions of pink shrimp should be more similar to
oceanic than coastal fish species.
However, four of the five
dominant offshore larval fish species were more abundant in 1971
than 1972, with Engraulis mordax as the exception (Richardson and
Pearcy, 1977).
Apparently, as with spring-summer holoplankton and
crab larvae, the response of pink shrimp larvae to hydrographic
variability is different from that of fish larvae.
Differences in
larval food, vertical distribution of early life history stages,
physiology, or spawning phenology might explain the differences
observed between abundances and times of planktonic occurrences of
fish larvae and crustaceans off Oregon.
Spawning Seasons, Transport Mechanisms and Early Life
Histories of Coastal Eastern North Pacific Fishes
Three seasonal spawning strategies by fishes were found in
this study.
Larvae were classified as occurring in 1) the winter,
2) the spring and summer, or 3) over an extended time period from
autumn through spring, in the exceptional case of Parophrys
vetulus.
Winter species, such as Ammodytes hexapterus and Ophiodon
elongatus, were found as pelagic larvae during a short season,
December through March, during onshore surface water transport and
northward meridional transport.
Spring and summer species, the
largest species-group dominated by the Osmeridae and Pleuronectidae
other than Parophrys, occurred as pelagic larvae in the late winter
into midsummer.
The time of first appearance of these larvae was
variable among years.
These were species whose larvae were pelagic
in the season of increased productivity due to upwelling, but which
were at risk of offshore zonal and strong southward meridional
transport during upwelling events.
Parophrys vetulus extended
their spawning season over a longer time period, September through
May with extreme variability among years, primarily during onshore
transport but extending into the upwelling season in some years.
The Parophrys strategy seemed to be one of bet hedging, with
protracted spawning and multiple peaks of larval abundance.
82
Within 30 km of shore, chlorophyll concentrations are
generally low from November through February and high from June
through August during upwellinQ (Small and Menzies, 1981).
Zooplankton abundances are low in November through April
,
and high
during the upwelling season starting in June (Peterson and Miller,
1977).
Zooplankton remains abundant through the transitional
months of September and October, when larval fishes are rare.
A
short winter peak of zooplankton abundance usually occurs in
February or March, when small early life history stages of copepods
are abundant.
Zooplankton concentrations are low in April and May
(Peterson and Miller, 1977).
I propose that the winter spawners, such as Ammodytes, place
their larvae in the water at a time of increased probability of
riearshore retention but increased risk of mis-match with the short
period of zooplankton abundance in February or March.
These
species may be more like the north Atlantic species studied by
Cushing (1969,1975) than other coastal Oregon species in their need
to match the timing of their pelagic larval stage with productivity
cycles.
However, they also risk having food concentrations
frequently disrupted by storms, leading to increased mortality as
proposed by Lasker (1978, 1981a,b).
Parophrys vetulus adopts a
different strategy of prolonged larval occurrence, with pelagic
larvae occurring throughout the period of low productivity.
Most
coastal fish species off Oregon place their larvae in the water at
a time of increasing food concentration, with increased risk of
offshore transport and disruption of food concentrations by
upwelling.
These species do not rely on a match with productivity
as much as the occurrence of hydrographically stable periods
following brief upwelling (Lasker, 1981a,b).
Certain species, such
as many Sebastes species, Glyptocephalus zachirus and Microstomus
pacificus, have solved the problem of offshore transport by having
prolonged dispersive larval and prejuvenile stages (Pearcy et al.,
1977; Moser, 1981).
Another, Engraulis mordax, occurs
planktonically in stable frontal zones associated with the Columbia
River plume (Richardson, 1981).
Some, such as Trichodon trichodon
and Ascelichthys rhodurus, exhibit rapid swimming behavior near the
bottom immediately after hatching, enabling them to remain in
extreme nearshore areas or avoid entrainment into upwelled water
(Marliave, 1981).
Most other coastal fishes in the northeastern
Pacific, with the exception of the Pleuronectiformes, have
partially solved the problem of offshore transport by having
parental care of the embryos either with demersal eggs (e.g.
Osmeridae, Cottoidei, Blennioidei) or viviparity (Sebastes spp.,
Embiotocidae) (Kendall, 1981).
Many species with demersal eggs
also have greater yolk investment of prefeeding embryos which may
lead to larger size at hatching with better ability to both capture
a larger size range of food and avoid predators (Kendall, 1981).
Both abilities would be advantageous to larvae in the
hydrographically unstable coastal upwelling zone.
Parrish et a]. (1981; abstract, p. 175) stated that "In the
Pacific Northwest, coastal fish species having pelagic larvae tend
to spawn during winter when surface wind drift is generally
directed toward the coast, rather than during the more productive
upwelling season.'
This is an oversimplification.
When the
majority of coastal Oregon taxa having pelagic larvae are
considered, it is wrong; most spawn during the late winter and
spring.
The statement by Parrish et al. (1981) in their abstract
is also contradicted in their text when they state (p. 192) that
most members of Richardson and Pearcy's (1977) inshore assemblage
were spring spawners, and where they discuss (p. 191) reproductive
strategies that minimize advective loss of eggs and larvae.
Parrish et al. (1981) present thought-provoking hypotheses, but
their paper understates the variety of early life history
strategies found in Pacific Northwest marine fishes.
In addition to the variety of reproductive and early life
history strategies discussed above, other factors may help retain
larvae of coastal fishes nearshore along the narrow Oregon
continental shelf.
Richardson and Pearcy (1977) suggested that
alongshore fronts might retain larvae in coastal waters.
This
mechanism would be necessary only during upwelling, because zonal
transport is onshore during the winter, but fronts might exist in
both seasons (Richardson and Pearcy, 1977).
They also pointed out
that advection along the Oregon coast is primarily meridional.
Loss of larvae from the region could be prevented by current
reversals, which may cause net north-south flow to be zero in both
summer and winter (Pearcy et al., 1977; Richardson, and Pearcy,
1977).
Even during active upwelling periods of extreme offshore
and southward transport, larval fish could be retained by fronts
EI1
and recirculating cells that have been demonstrated to retain
zooplankton (Peterson et al., 1979).
Persistent concentrations of
many species of larval fish at 6-9 km offshore during periods of
one or more months in the spring and early summer of each year in
this study suggested that larvae are retained within the region.
As suggested by Richardson and Pearcy (1977) and Richardson et al.
(1980), transport away from favorable areas may be less important
to the survival of coastal Oregon fish larvae than other factors.
Three major hypotheses pertaining to survival of larval fishes
in upwelling regions were summarized in the Introduction: Cushing's
(1969,1975,1978) match/mismatch hypothesis, Parrish et al.'s (1981)
transport hypothesis, and Lasker's (1975,1978,1981a,b) stability
hypothesis.
All of these explain aspects of the seasonality and
annual variability of larval fish abundance off Oregon.
The
match/mismatch hypothesis does not explain the spawning seasonality
of coastal Oregon fish, nor does it account for the annual
variability of the three most dominant spring-summer species.
None
of the fish species in this study had their peak of abundance
during the peak of zooplankton abundance, and few of the
spring-summer species were most abundant in the year of greatest
zooplankton abundance.
However, the match/mismatch of individual
larval fish species with the abundance of their particular prey
within a season may be important for larval survival.
Too little
is known about feeding in most coastal Oregon fish larvae to
determine the applicability of the match/mismatch hypotheses to
their survival.
Offshore transport of larvae may be less important
than other factors in influencing the survival of Oregon fish
larvae, as discussed earlier.
However, selection on coastal
species via transport-related larval mortality has been important
in determining both the variety of early life history strategies of
fishes in the region, and the spawning seasons of many species
(Kendall, 1981; Parrish et al, 1981).
The possible importance of
upper mixed layer stability (Lasker, 1975,1978,1981a,b) is
indicated by the negative influence of winds, as associated with
winter storms and summer upwelling, on the abundances of the
majority of coastal Oregon larval fish species.
The third power of
wind speed ("wind cubed") is a promising tool for assessing the
effects of wind induced mixing of the upper ocean on larval fish
survival (Husby and Nelson, 1982). Analyses of feeding, upper mixed
layer stability, and distributional patterns with respect to water
transport are the next steps toward understanding the factors that
influence the survival of larval fishes in Oregon's upwelling
areas.
LITERATURE CITED
Ahistrom, E.H.
1956.
Eggs and larvae of anchovy, jack mackerel,
and Pacific mackerel.
Calif. Coop. Oceanic Fish. Invest.
Prog. Rep., 1 April 1955 to 30 June 1956: 33-42.
Ahlstrom, E.H. 1965. A review of the effects of the environment
of the Pacific sardine.
Internatl. Comm. for No. Atlantic
Fish., Spec. Pubi. No. 6: 53-74.
Ahlstrom, E.H. 1965.
Kinds and abundance of fishes in the California Current region based on egg and larval surveys. Calif.
Coop. Oceanic Fish. Invest. Rept. 10: 31-53.
Ahistrom, E.H.
1972.
Distributional atlas of fish larvae in the
California Current region: six common mesopelagic fishes,
Vinciguerria lucetia, Triphoturus mexicanus, Stenobrachius
leucopsarus, Leuroglossus stilbius, Bathylagus wesethi and
Bathylagus ochotensis, 1955 through 1960.
Calif. Coop.
Oceanic Fish. Invest. Atlas 17: 317 pp.
Ahlstrom, E.H., J.L. Butler and B.Y. Sumida. 1976.
Pelagic
stromateoid fishes (Pisces, Perciformes) of the eastern
Pacific: kinds, distribution, and early life histories and
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TAB L ES
106
Table I:
Two-way Coincidence
Table for Individual Years (Sept.
Excluding Multispecies Taxa.
- August),
(All time and species
groups form at a Bray-Curtis Dissimilarity Value of 0.5).
a)
Sept., 1969 - August, 1970
Time Groups
1
2
3
4
Species
1
-
.93
-
-
Groups
2
-
.33
-
-
3
-
.67
.38
-
4
-
-
.63
-
5
-
.25
.94
.36
Sept., 1970 - August, 1971
b)
Time Groups
1
3
4
1.00
.25
-
2
Species
1
Groups
2
-
.75
.25
-
3
-
.50
.25
.33
4
.07
.71
.89
.43
c)
1.00
Sept., 1971 - August, 1972
Time Groups
1
2
3
4
Species
1
-
.75
.42
.25
Groups
2
-
.38
.92
.63
3
-
-
.75
-
Table II:
a).
Taxonomic Composition and Times of Occurrence of Each Species-Group in:
a). 1969-1970, b). 1970-1971 and c). 1971-1972.
1969-1970
pecies Groqp
Dom!Jcies
etua
1
Other Taxa
taulis mordax
Months of Occurrence
Months of MosLe!t
(Time Group)
Occurrence (Time Group)
Jan.-March (2)
Jan.-March (2)
Jan.-March (2)
Jan.-March (2)
Jan.-May (2&3)
Jan.-March (2)
April-May (3)
April-May
(3)
Jan.-May,July,Sept. (2,3&4)
April-May
(3)
(large larvae only)
Hemilepidotus !E!
4on
tus
Stenohrachius leucopsarus
2
Platichthvs stellatus
Ec!
3
Microgadus pm
none
spp.
Artedius fenestralis
exilis
psetta isolepis
4
5
Clinocottus acuticeps
none
melanostictus
Artedius
Artedlus meanyi
b).
1970-1971
1
2
Parophy vetulus
none
Hemilepidotus ps
Pholis app.
Dec.-June (l,2&3)
Feb.,May&June
Dec.-Feb. (l&2)
(2&3)
Feb.
(2)
Feb.-July (2,3&4)
Feb.
(2)
Enophrys bison
3
none
Clinocottus
!R2
4
tta
none
!cIItIs melanostictus
MI crogadus p2mus
Artedius
4o1
Dec.-July (l,2,3&4)
Feb.,May&June (2&3)
Table 11 - ContInued
Months of Occurrence
srou
Dominant Species
Other Taxa
(rp)
Occurrence (Time Croj
cItIy stellatus
Artedius meanyJ.
Artedjus fenestralis
c).
1971-1972
1
Ammodytes hexapterus
Microgadus ExiInus
2
isolepis
Artedius harringtonl
Cottus aspe
ocotttis acuticeps
none
March-Aug.
(2,3&4)
March
March-Aug.
(2,3&4)
April-June
(3)
April-June
(3)
(2)
yopsetta exilis
Artedius fenestralis
3
P1atichtIy stellatus
Artedius meanyl
ys bison
Ronguilus jordani
April-June (3)
109
Table III:
Summary of Kruskal-Wallis Tests for Differences
in Abundance of Larvae Between Years.
Critical x2 values:
90% (2 d.f.) = 4.605; 95% (2 d.f.,)
5.991; 99% (2 d.f.) = 9.210
H value
Taxon
for Sept. -Sept.
All taxa
1.538
Osmeridae
8.328*
Microgadus proximus
2.345
Sebastes spp.
.088
Artedius harrinytoni
3.709
Artedius fenestralis
1.231
Artedius meanyi
1.474
Ammodytes hexapterus
2.827
Isopsetta isolepis
0.617
Lyopsetta exilis
1.487
Parophry
1.296
vetulus
Platichthys stellatus
2.508
Psettichthys melanostictus
0.619
110
Table IV:
Modified Eager's Biological Indices of Dominance
(Richardson, 1973) for the Thirteen Most Abundant Taxa
in
Taxon
each of Three Years.
1969-70
B.I.
1970-71
Rank
8.1.
1971-72
Rank
B.I.
Rank
Osmeridae
1.02
1
2.22
1
1.72
1
Parophrys
vetulus
0.80
2
1.05
3
0.52
5
Isopsetta
isolepis
0.66
3
1.06
2
0.97
2
Psettichthys
melanostictus
0.53
4
0.17
12
0.58
4
Microgadus
proximus
0.22
8
0.73
4
0.42
6
0.53
4
0.45
5
0.39
7
0.39
5
0.44
6
0.73
3
0.24
7
0.19
10
0.32
9
Platichthys
stellatus
0.12
13
0.18
11
0.42
6
Lyopsetta
exilis
0.04
23
0.23
8
0.26
10
Artedius
meanyi
0.25
6
0.09
17
0.08
15
fenestralis
0.18
9
0.26
7
0.35
8
Cyclopteridae
Type 1
0.06
21
0.19
10
0.25
11
*
*
Sebastes
spp.
*
Artedi us
harringtoni
Amniodytes
hexapterus
*
*
*
*
*
Artedi us
*
*
* indicates tied ranks
111
Table V:
Month
Days per Month with Winds Greater than 15 knots.
(*greater
than 20 kts)
1969
1970
1971
1972
*
January
12(5
February
4
March
5
)
*
14(6 )
11(1*)
15(6
11(5
12(4*
)
*
April
6(2
May
*
)
1
5
7(2
2
4
2
4
*
June
0
5(1
July
4
3
4
2
August
1
0
2
2
September
2
0
)
1
*
October
5(1
1
*
November
4(1
)
7(2
4(2
*
7(4
*
December
*
)
)
8(2
*
)
12(6
)
*
)
*
)
14(3
Number of Days of Storms per Month
(Winds > 15 kts;
Month
1969
Precipitation > 1.0 cm)
1970
1971
1972
January
9
13
11
February
3
9
12
March
4
14
7
April
4
4
0
May
0
0
0
June
0
0
2
0
July
0
0
0
0
August
0
0
1
0
September
2
0
0
October
1
5
4
November
2
7
8
December
5
12
13
112
Table VI:
Month
1969
Average Monthly Precipitation (cm).
1970
1971
1972
January
1.57
1.27
1.15
February
0.75
0.65
0.64
March
0.65
0.74
0.94
April
0.74
0.64
0.58
May
0.21
0.17
0.18
June
0.48
0.09
0.32
0.15
July
0.04
0.03
0.09
0.04
August
0.03
0.03
0.13
0.09
September
0.34
0.37
0.54
October
0.99
0.44
0.51
November
0.44
0.75
0.89
December
1.26
1.15
1.64
Number of Days with Precipitation Greater than 1.0 cm in Each Month
Month
1969
1970
1971
1972
17
14
11
February
5
9
12
March
4
14
9
April
9
5
6
May
1
1
2
January
June
6
1
3
1
July
0
0
1
0
August
0
0
2
1
September
5
4
6
October
7
6
6
November
4
8
11
December
15
12
14
113
Table VII.
Dates on Which Major Storms Occurred, 1969-1972.
From wind and precipitation data.
Storms
(wind > 15 knots,
1969
rain > 0.4 inches,
1971
1972
Sept. 17
Jan. 8_17**
Sept. 30
Jan. 22
Oct. 27
Nov. 5_6*
Dec. 10_12*
Dec. 14
Dec. 22*
Dec. 25
Jan. 24_25*
Feb.
9
Feb. 14-15
Feb. 18
Feb. 23_27*
March
2
March 9_12*
1970
March 14
Jan. 13_14*
March 22_23*
Jan. 17_19*
March 25_30*
Jan. 22*
April 10
Jan. 24_25*
April 16-17
Jan. 31*
April 24
Feb. 15-17
*winds > 20 knots)
June 18
Jan. 7_ll*
Jan. 16
Jan. 18_20**
Jan. 23*
Jan. 27
Feb.
2
Feb. 11_12*
Feb. l4_17*
Feb. 19
Feb. 24
Feb. 27-March 1*
March 4_5*
March l0_12*
March 18
March 24
April 5_8*
June 24
April 11-12
March
12
August 31.
April 24
March
14
Oct. 18_19*
March 5-6
April
5
Oct. 26
April
9*
Oct. 30
April 18
Nov.
9
April 24*
Nov. 13*
Oct. 20_24*
Nov. 23_28*
Nov. 15*
Dec. 3_6*
Nov. 22_24*
Dec.
9
Nov. 26
Dec. ll_14*
Nov. 30*
Dec. 20_22*
Dec.
3
Dec. 5_6*
Dec. 10
Dec. 14_16*
Dec. 20
Dec. 27_28*
Dec. 25
May 17
May 21
July
8
114
Table .TIII.
Date
Surface Temperatures at each Station on each Sampling Date.
NH 1
NH 3
NH 5
NH 10
Mean
June 22
12.6
12.7
12.9
13.8
13.0
29
14.4
14.6
-
--
1.4.5
July 10
10.2
-
11.3
10.4
10.6
18
9.6
11.3
9.5
10.5
10.2
25
8.5
8.0
7.9
8.3
8.2
30
--
--
--
8.6
8.6
1969
Aug.
Sept.
Oct.
6
10.0
9.0
10.3
11.6
10.2
26
11.1
11.0
11.2
12.8
11.5
30
11.7
11.6
11.8
14.0
12.3
3
8.8
9.0
9.4
10.0
9.3
14
--
8.5
8.5
--
28
13.6
13.7
13.9
14.4
8.5
13.9
--
--
--
--
--
23
11.6
11.9
12.0
12.2
11.9
8
29
12.1
12.2
12.2
12.1
12.2
Nov. 11
11.5
11.8
11.9
12.0
11.8
18
11.1
11.2
11.5
11.7
11.4
2
10.5
10.6
10.6
10.9
10.7
9
10.4
10.8
10.8
-
10.7
29
10.3
10.1
10.4
10.9
10.6
Dec.
1970
9.8
Jan. 13
9.8
--
--
--
29
10.5
10.4
10.4
10.7
10.4
Feb. 13
10.9
10.8
11.1
11.4
11.1
25
11.3
11.4
--
--
11.4
9
10.9
10.7
10.9
10.8
10.8
9.7
--
March
April 16
--
9.7
--
--
27
--
--
--
--
May1
--
--
--
-
June
JuLy
Aug.
Sept.
6
9.1
8.9
9.2
9.8
9.3
22
10.4
11.6
12.6
12.6
11.8
9.1
4
8.6
9.2
9.6
--
23
7.6
7.3
3.2
8.5
7.9
2
12.4
11.9
11.9
14.0
12.6
16
--
29
12.3
9.2
9.9
9.6
9.6
11.3
13.3
13.9
12.7
13
8.9
9.2
8.3
9.2
8.9
27
11.1
10.7
10.3
12.1
11.1
11
8.8
8.8
8.9
9.9
9.1.
25
10.6
10.6
10.8
16.0
12.0
115
Table VIII - Continued
Date
Oct.
NH 1
NH 3
NH 5
NH 10
Mean
11.3
9
10.7
11.4
12.1
10.9
20
10.3
10.4
10.3
10.7
10.4
4
11.4
11.3
11.2
11.9
11.4
Nov.
Dec.
4
9.0
9.6
9.7
10.6
9.7
21
9.6
9.9
10.0
10.6
10.0
1971
Jan.
6
8.0
8.1
8.2
7.4
7.9
18
9.5
10.5
9.9
9.8
9.9
3
8.4
8.8
8.7
8.6
8.6
16-17
9.5
9.3
9.2
9.0
9.3
1
8.3
7.8
8.2
7.9
8.1
20-21
8.7
8.6
8.6
8.4
8.6
30
9.4
9.8
8.8
8.7
9.2
-
--
9.5
9.6
9.6
May 3-4
9.9
10.4
10.6
10.7
10.4
14-20
11.9
11.4
11.4
11.2
11.5
29-30
9.1
8.7
8.1
9.1
June 1-2
10.8
9.3
--
--
10.1
12-13
13.2
13.2
13.3
13.7
13.4
28-30
14.2
14.5
3.4.5
14.1
14.3
6
10.3
10.7
11.5
14.3
11.7
21-22
8.5
9.3
9.1
9.1
9.0
Aug. 2-3
13.7
14.3
14.1
16.6
14.7
15.0
Feb.
March
April 22-26
July
8.8
19-20
14.0
14.4
15.5
16.1
Sept. 23-24
10.3
10.3
10.2
10.4
10.3
Oct. 11-12
12.4
12.4
12.3
12.4
12.4
Nov. 6-7
9.6
9.8
9.8
10.4
9.9
9.6
9.2
8.4
9.1
Dec.
7
1972
March 3-4
9.8
9.3
9.6
9.3
9.5
15-16
10.6
11.1
11.4
11.7
11.2
29-30
10.4
--
9.7
9.6
9.9
April Il
10.3
10.4
10.2
10.1
10.3
--
20-21
10.0
9.7
9.4
9.7
May 22-23
9.8
9.9
10.3
10.5
10.1
June 11-12
10.1
10.4
10.7
10.7
10.5
28-29
10.3
9.7
9.9
11.9
10.5
July 21-22
10.3
10.5
10.5
11.7
10.8
8.5
8.6
5.5
9.0
8.7
Aug.
5
116
Table IX.
Surface Salinity at Each Station on Each Sampling Date
(Columbia River Pltmie Water ' 32.5 0/00)
Date
NH 1
NH 3
NH 5
NH 10
Mean
June 22
32.42
32.46
32.50
30.74
32.03
29
30.79
31.18
28.38
25.18
28.88
--
--
-
--
--
18
33.78
34.70
33.07
32.22
33.44
25
34.22
33.86
33.74
32.76
33.65
30
--
-
--
33.16
33.16
6
33.56
33.54
33.26
32.60
33.24
26
33.14
32.14
32.96
31.52
32.43
30
33.14
32.62
32.60
32.10
32.62
3
33.15
1969
July10
August
Sept.
Oct.
33.85
32.70
33.48
32.56
14
--
33.90
33.92
--
33.91
28
32.08
-
32.16
32.38
32.13
8
-
--
--
--
--
23
33.54
33.38
33.10
33.22
33.31
29
33.42
33.14
33.34
33.38
33.32
Nov. 11
33.24
33.47
33.48
33.34
33.36
18
33.46
33.42
33.25
33.42
33.39
2
32.38
31.15
32.18
32.21
31.96
9
--
--
-
-
--
29
--
--
-
--
Dec.
1970
Jan. 13
31.61
--
--
-
31.61
29
28.25
27.68
27.64
31.29
28.72
Feb. 13
29.94
29.01
30.20
31.26
30.10
25
--
--
--
--
9
30.96
30.10
31.10
April 16
--
33.06
27
--
--
-
--
--
1
--
--
--
--
--
arrh
May
June
July
-30.54
--
33.06
6
33.33
33.32
33.00
31.92
32.89
22
33.10
33.05
33.01
30.95
32.53
4
33.77
33.68
33.41
--
33.47
23
33.19
33.91
33.36
33.25
33.45
2
33.43
33.58
33.04
31.31
32.84
16
--
--
--
--
29
33.31
33.49
31.96
31.73
32.66
Aug. 13
33.77
33.74
33.55
32.92
33.50
27
33.76
33.58
33.39
32.41
33.29
11
33.77
33.77
33.61
33.17
33.58
25
33.27
32.69
32.68
32.80
32.86
Sept.
117
Table IX - Continued
Date
Oct.
Nov.
NH 1
NH 3
NH 5
NH 10
Mean
9
33.48
33.32
33.30
33.16
20
32.99
32.89
32.90
32.63
32.85
4
32.82
32.94
32.98
32.74
32.88
4
30.35
30.45
30.15
32.49
30.86
21
30.71
30.76
30.87
32.37
31.18
Dec.
33.32
1971
Jan.
6
31.40
31.19
31.40
31.69
31.42
18
28.14
25.17
32.32
32.39
29.51
3
32.07
32.04
31.50
30.59
31.55
16-17
30.55
30.45
31.48
31.54
31.01
1
32.40
31.75
32.29
31.96
32.10
20-21
32.37
32.20
32.12
32.16
32.21
30
30.16
29.80
30.85
32.45
30.82
--
--
32.42
32.48
32.43
May 3-4
31.21
31.35
31.06
29.34
30.74
Feb.
March
April 22-26
14-20
32.03
31.81
31.25
30.95
31.51
29-30
33.68
33.66
33.57
33.86
33.69
June .1.2
33.60
33.44
--
-
33.26
12-13
30.08
29.73
30.93
29.42
30.04
28-30
30.83
30.86
32.30
30.93
31.23
6
33.44
33.41
33.32
27.18
31.84
21-22
33.85
33.57
33.50
33.21
33.53
Aug. 2-3
33.38
33.25
33.19
29.72
32.36
19-20
32.86
32.82
32.77
32.86
32.83
Sept. 23-24
33.22
33.04
32.77
32.48
32.88
Oct. 11-12
32.72
32.73
32.77
32.46
32.67
Nov. 6-7
32.33
31.80
31.64
31.77
31.89
7
31.89
32.08
-
31.38
31.78
March 3-4
25.05
28.11
35.92*
32.33
28.50
15-16
29.21
25.88
29.47
32.19
29.19
27-30
30.92
--
31.61
32.17
31.53
April 11
30.28
30.49
31.31
31.96
31.01
19-22
21.37
--
19.30
17.12
19.26
29-30
--
--
--
--
--
May 22-23
31.73
31.74
31.29
31.10
31.44
June 11-12
32.89
32.24
31.83
31.98
32.24
28-29
33.31
33.20
32.94
32.30
32.94
July 21-22
33.68
33.51
33.57
32.70
33.37
Aug.
33.82
33.79
33.22
32.93
33.44
July
Dec.
1972
5
*false measuretnent (see footnote
1, p
118
Table X:
Bottom salinities at each station on each sampling date when measurements were taken.
Date
NH 1
NH 3
NH 5
NH 10
Mean
July 18
33.78
34.70
33.18
33.00
33.67
25
34.33
34.38
34.06
33.20
34.01
August 30
33.46
33.72
33.22
32.66
33.27
--
32.24
--
1969
Dec.
2
-
32.24
1970
Jan. 13
32.39
--
--
--
32.29
29
30.23
31.65
32.21
32.50
31.65
Feb. 13
30.74
32.24
32.39
32.83
32.03
March
9
31.54
32.02
32.46
--
32.01
May
6
33.79
33.86
33.89
33.84
33.85
22
33.45
33.57
33.91
33.84
33.69
4
33.87
33.92
33.93
--
33.91
23
33.74
33.84
33.93
33.89
33.85
July 29
33.91
33.93
33.94
33.94
33.93
August 13
33.86
33.91
33.91
33.92
33.90
27
33.84
33.82
33.86
33.55
33.77
9
33.62
33.81
33.85
33.90
33.80
20
33.16
33.38
33.73
33.87
33.54
Nov.
4
32.32
33.23
33.27
-
33.11
Dec.
4
32.30
--
32.55
33.79
32.55
21
31.49
31.72
32.22
32.52
31.99
June
Oct.
1971
6
31.57
32.36
32.87
32.40
32.30
18
30.99
32.16
32.35
32.59
32.05
3
32.62
33.14
33.55
33.60
33.23
16-17
31.37
32.53
33.05
33.58
32.63
1
33.42
33.70
34.56
33.77
33.86
March 20-21
32.41
32.77
32.27
33.43
32.72
30
31.71
31.72
32.44
32.49
32.01
--
--
34.18
34.67
34.43
May 3-4
32.63
33.44
33.59
33.80
33.37
14-20
32.04
33.43
33.73
33.83
33.24
29-30
33.75
33.92
33.91
33.84
33.86
June 1-2
33.72
33.86
--
--
33.79
12-13
33.30
33.81
33.84
33.83
33.65
29-30
31.47
33.68
32.27
33.82
32.81
6
33.72
33.80
33.84
33.89
33.81
21-22
33.88
33.84
33.87
33.86
33.86
August 2-3
33.51
33.81
33.86
33.92
33.78
19-20
32.90
33.37
33.59
33.80
33.42
Jan.
Feb.
March
April 22-26
July
119
Table X - Contitiued
Date
NH 1
NH 3
NH 5
NH 10
Mean
Sept. 23-24
33.28
33.57
33.64
33.68
33.54
Oct. 11-12
33.31
33.46
33.50
33.70
33.49
6-7
32.48
32.47
33.60
33.73
33.07
7
32.22
32.26
-
33.51
32.50
32.00
Nov.
Dec
1972
March 3-4
31.20
32.09
32.16
32.56
15-16
30.96
31.63
32.32
32.84
31.94
27-30
32.47
--
32.74
33.13
32.75
April 1].
31.32
32.11
32.07
32.34
31.96
19-22
32.72
--
32.87
33.51
33.03
May 22-23
32.91
32.94
33.60
33.54
33.25
June 11-12
32.85
33.60
33.76
33.81
33.51
28-29
33.74
33.50
33.83
33.87
33.81
July 21-22
33.76
33.83
33.87
33.88
33.84
33.83
33.85
33.87
33.87
33.86
August
5
FIGURES
1 20
Figure
I
Location of Stations Sampled Stations Designated With
Open Circles Were Sampled From 22 June - 20 Oct. 1970.
Stations Designated With Solid Circles Were Sampled
From 4 Nov. 1970 - 5 Aug. 1972.
l20
450
45'
;50
50'
11
Figure 2
2
Mean Standardized Abundance Of All Taxa IE(No. Larvae/IOm )/No. Stations Sampled]
0
0
(I)
0
z
0
0
0
>
0
I.-
-I
a
z
4)
1969
1970
-J
N)
Figure 3
Mean Standardized Abundance Of All Taxa {E(No. Larvae/10m2)/No. Stations SampiedJ
At All Stations Sampled On Each Dote In 1970- 1971
4.-
0
Cl)
33J- _,7c49
z0
200
0
4,
0
0
-J
0
z
150
4,
0
>
0
-J
.4-
0
4)
0C
0
100
0C
0
4)
N
4-
0
0
C
0
50
Cl)
C
0
4)
Sept.
'
Oct.
'
1970
Nov.
Dec.
J
Jan.
Feb.
' March '
April
May
1971
' June ' July
' Aug.
N)
N)
Figure 4
Mean Standardized Abundance Of All Taxa IE(No. Lorvae/lOm2)/No. Stations Samoledi
197
l972'
N)
(JJ
Figure 5 a
Time Groups From the Classification Analysis Using Data From $969- 1970,
Excluding Osmerids, Sebastes, and Cyclopterids.
Bray
0
I
.1
.2
Curtis Dissimilarity Value
.3
.4
.5
.6
.7
.8
.9
1.0
November 18, 1969
December 2, 1969
December 20, 1969
February 13, 1970
2 February 25, 1970
January 29i 1970
March 9, 1970
May 6, 1970
3 May 22, 1970
May I, 1970
April 27, 1970
July 2, 1970
August 13, 1970
1June 23, 1970
September 3, 1970
July 16, 1970
November II, 1969
-1
Figure 5b
Species Groups From the Classification Analysis Using Data From l969- 1970,
Excluding Osmerlds, ebastes, and Cycloptorids.
0
.1
Bray- Curtis Dissiftillority Value
.5
.3
.4
.2
.6
.7
.8
.9
1.0
Qphiodon iQnga1u
HemiJepjf
i
pinosus
Enggfls mordox
Stenobrochius eutopsarus
Ammôdytes tgpjLs
DQPJQLLth1L
spp.
Plotichthys stellatus
Clinocottus acuticeps
Lyopselta exiis
Cottus osper
3 Microgadusproximus
Artedius fenestralis
Artedius meanyi
fettichthy melanoslictus
5
i9pJ
Artedius harringtoni
Porophrys vetulus
jordani
N)
cJ'
Figure 6
Time Groups and Species Groups From the Classification Analysis Using Data From 1970-1971,
Excluding the Osmerids, Sebostes, and Cyclopterids.
0
a) Time Groups
.1
dray
.2
.1
.2
Curtis Dissimilarity Value
.3
.4
5
.6
.7
.8
.9
1.0
May 4, 1971
June 2, 1971
May 29, 1971
May 3, 1971
2
February 3, 1971
February 16, 1971
July 6, 1971
July 21, 1971
June 28, 1971
March 30, 971
Au gust 2, I 97i
December 21, 1970
January 6, 1971
Januory 8, 1971
September 25, 1970
October 20, 1970
b) Species Groups
promus
opi#flg
0
.3
.4
.5
.6
.7
.8
.9
oIep
Psettichthy
meIarostj
Artedius fenestralis
Artedws harrinorn
u
rnapyj
chthys stellatus
yito eMItS
CQflJ,L QPer
ClinoCottus ocuticaps
psus
i9Ph!Y! vetulus
2
P2il
SSp.
Ammod
hexaptus
HIeptus
Ieotus
4
N)
Figure 7
Time Groups and Species Groups From the Classification Analysis Using Data From 1971-1972,
Excluding the Osmerids, Sebastes, and Cyctopterida.
a) Terne Groups
0.1
Bray
.2
Curtis Dissimilarity Value
.3
.4
.5
.6
.7
.8
.9
1.0
September 23, 1971
December 7, 1971
2 March 3, 1972
March 15, (972
May 22, 1972
June II, 1972
2
3
April Il, 1972
4 June 28, 1972
August 5, 1972
July 21, 1972
b) Species Groups
2!I
0
.1
.2
,3
.4
.5
.6
.7
.8
.9
PLY bOfl
jrdoi
Platichthys stellotus
jus meonyl
Artedius fenestralis
2 lsopjjg,
O(epj
Aedius hoingrnffl
Lyopsetta eci1ts
psettichthys meIariostic1stictus
Cottus osper
Clinocottus 2t!hceP!
Microgadus proximus
Anmodytes hexopj
Parophry
yjS
-J
128
Figure 8
Month'y Standardized Length Frequencies of Osmeridae
c..J
ID
July, 1969
ii
-
E
2
1
0
5
I
Aug.,l96
5
I°i
30
ao Standard Length (mm)
0!
35
40
40
Dec., 1969
301
March, (970
2ci
Jan., 1970
5
0
N1
5
0
5
2C
April, (970
MOY, (970
z:z
0
o
1168
0
5
-j
S
-J 15c
5
10
5
0
5
5
98
2L
5
)
10
June, (970
5
20
as
20
25
_JuIy,197O
_
IS
Sept.,1970
TO
5
0
5
ao
5
ao
0ct.,l97 If
5
ID
Nov., (970
5
10
15
20
Standard Length (mm)
I
35
U
45
Dec., 1970
Standard Length (mm)
30
25
D
55
129
Figure 8
Monthly Standardized Length Frequencies of Osmeridae
(continued 2)
3C
20
60
EI0j97L
5
0
50
E
240
20
5
-
.
II
0
___L1IL_.
5
0
5
L
10
5
10
L
20
20
March, 971
0
20
15
May 4, 971
5
IC
15
20
25
30
-S
El
C.)
(VI
-'I
0
2 601
a,
I
501
C
I
I
May 3,
-
1971
__
I
..140I
IMay 29,
1971
a,
C
>
a
I-
lI,
5
5
10
5
20
Standard Length (mm)
25
0
5
20
25
Standard Length (mm)
30
130
Figure 8
Monthly Standardized Length Frequencies of Osmeridue
(continued - 3)
1401
20
June 28, 971
90
so
cJ
0
70
I-
a
-J
0
a
>
a
I-
-J
Standard Length (mm)
aol
July) 1971
I0
I
j
4
0
5
20
25
30
35
40
5
20
25
30
05
40 45
25
30
10
August, 1971
0
0
Oct., 1971
1
Dec., 1971
0
5
20
Standard Length (mm)
131
Figure 8
Monthly Standardized Length Frequencies of Osmeridae
(continued - 4)
N
E0
C
March
1972
'
0
July, 1972
0
5
20
25
August, 1972
0 a
tO
15
20
25
30
Standard Length (mm)
April, 1972
CI
20
90
N
E
2 70
May, 1972
60
C
-J
50
40
I,J
June, 1972
5
10
IS
20
25
Standard Length (mm)
35
40
132
Figure 9
Monthly Standardized Length Frequencies
of Parophrys vetulus
30
120
tIC
5
Feb., 1970
0
10
50
4o
15
I March, 1970
ac
Nov., 1969
, 30
4,
5
>
4,
0
5
April, 1970
to
-J
I0
5
5
0
IS
50
101
IC
15
20
May,.19?O
-
40
5
Dec., 1969
30
10
10
IS
20
25
30
20
25
30
June, 1970
20
15
I
l0
5
tO
0
IS
Standard Length (mm)
IS
Jan., 1970
S
IC
5
20
Standard Length (mm)
133
Figure 9
Monthly Standardized Length Frequencies
of Parophrys vetutus (continued-2)
Dec., 1970
C420
5
1971
E
10
0
to
I
1971
C
A
5
LI
C
tO
15
20
-J
April, 1971
5
I
tO
5
240
230
20
tO
15
20
May, 1971
I_I
220
2
2lO
5
140
5
tO
20
Standard Length (mm)
30
C'J
E
2 ao
ol
Feb., 1971
Oct., 1971
>
0
-j
to
5
E
80
Nov., 1971
230
tO
15
Dec., 1971
20
60
C
-jto
50
40
____
5
J
0
5
March, 1972
5
20
10
tO
IS
Standard Length (mm)
to
5
tO
IS
Standard Length (mm)
134
Figure 10
Monthly Standardized Length Frequencies of
Isopsetta isolepis
August, 1969
20
March, 197!
201
I
0
March, 1972
20
5
I
101
tO
20
IS
I
5
101
10
April, 1971
Sept., 1969
101
5
0
IS
April, 1972
S
5
5
20
5
10
IS
j 5L_°0
5
10
IS
May, 1971
0
5
50
E
04
1970 2
10
0
5
IS
1972
E
2
0
a
.30
a
I-
a
>
-J
3°LI April, 1970
ac
-j
20
5
10
10
15
20
June 1972
rnWao
0
Io
5
5
10
5
20
15
20
0
5
20
20
0
10
04
E
30
0
20L
0
5
10
5
0
97!
Feb
5
Standard Length (mm)
0
0
IS
20
5
20
July, 1971
5
10
5
0
15
20
Standard Length (mm)
June, 970
5
July, 1972
10
August, 1971
5
10
IS
20
Standard Length (mm)
1 35
Figure II
Monthly Standardized Length Frequencies of
Psettichthys melanostictus
C
July, 1969
Feb., 1971
Ihi20
_JL:
5
N
I
E
IS
JO
9
IOj April, 1971
20
15
JO
March, (972
I-
Standard Length (mm)
I
Jo
a1
s
IS
JO
5
C
May, 1971
5
in
April, 1972
a
(0
15
JO
IS
May,
20
June, 1971
June, 1972
April, 1970
N
5
E
10
N
I
>
IS
20
Standard Length (mm)
(520
b04,5
May,
1970
(0
230
20
(0
5
E20 July,
Aug.,
1971
-a5
JO
IS
20
JO
JO
5
0
5
(3
20
(0
5
(0
5
20
25
JO
20
25
0
(0
(5
Nov., 1971
5
(0
(5
Standard Length (mm)
Aug., 1970
5
20
0
July, (970
5
1
25
June, 1970
5
Sept., 1971
20
25
Standard Length (mm)
136
Figure 12
Monthly Standardized Length Frequencies
of Microgadus proximus
June, 1969
0
5
IS
July, 1969
0
5
5
20
25
Aug.l969
5
5
5
20
IS
25
Feb.1970
.
5
5
tO
10
1I.h,l970
5
0
_*E!l, 1970
5
tO
- May, 1970
E
2
5
'
Junej97O
15
20
- July, 1970
5
1
-
_tO
tO
tO
February, 1971
25
E
0
-S
a
0
5
to
10
-4
March, 1971
to
April, 1971
Standard Length (mm)
5
0
15
Standard Length (mm)
137
Figure 13
Monthly Standardized Length Frequencies of
Sebastes spp.
June, 1969
0
5
30
1262
25QJ1
5
20
Oct., 1969
10
13011130
0
5
120
15
0
Nov.
2
a
>
Feb., 1970
5
0
5
5
0
5
5
0
15
[97l
a
-J 0
201
Dec., 1969
cu
E
0
301L
21
0
5
C
a
>
a
0
5
10
20
Standard Length (mm)
0
Oct., 1970
-j
5
5
March, 1971
0
15
April, 1971
15
5
10
IS
20
March, 1972
25
401
Is
1015
30
Jan., 1970
20
Dec., 1970
0
10
20
April, 1972
Ia
5
5
0
0
15
101
5
May, 1972
Standard Length Cm
5
0
15
Standard Length (mm)
5
0
5
Standard Length (mm)
138
Figure 14
Monthly Standardized Length Frequencies of
Artedius harringjj
20
30
June, 1969
0
I
0
I Jan., 1971
20
I
March, 972
)
E
I
July, 1969
20
III2
>
iiI
I
101
I
-j
I Feb., 97!
August,
(969
I
.
5
5
10
5
5
10
Sept., 1969
0
Ii
0
15
20Stad. Length (mm)E
April, 1970
10
5
ic
0
2
IS
April, 1971
I
5
'015
J May, 1971
II
May, (970
5
0
IS
June, (97!
5
o
5
10
June, 1970
5
.iNI
5
a
to
10
5
5
July,1971
July,
5
(970d
5
0
10
10
0
10
1015
August, (971
15
August, (970
1 I b
5
tO
15
Standard Length (mm)
Standard Length (mm)
5
10
June,
1972
15
-J
a
10
10
5
_Ii
March, 1971
5
I -10
5
0
May, 1972
0
a
5
10
6
0
15
April, (972
5
I
01
o
is
1
a'
0
5
J I
I'
5
15
10
o July, (972
I
5
10
5
Standard Length mm)
139
Figure 15
Monthly Standardized Length Frequencies
of Ammodytes hexapterus
Jan., 1970
Feb., 1971
5
tO
15
20
E
10
0
5
2
5
tO
March, 1971
-ito
5
to
ts
Standard Length (mm)
cJ
E
0
March, 1972
Feb., 1970
0
0
>
0
20
--
E1O
-J
0
5
5
101
tO
5
20
March, 1970
5
tO
IS
tO
0
Standard Length (mm)
IS
April. 972
I
3
5
20
tO
to
is
gtandard Length (mm)
140
Figure 16
Monthly Standardized Length Frequencies
of Platichthys stellatus
6 20
0
0
July, 1969
March, 1972
U,
a
5
-J
tO
II!]
IS
Standard Length (mm)
20,
10
EI
10
Feb., 1970
0
April, 1972
2
IC
l
U,
5
o 40
>
March, 1970
30
tO
10
3
0
IS
May,
1972
20
Standard Length (mm)
201
101
Feb., 1971
101
June, 1972
11
[ 5
IC
IS
101 April, 1971
6
040
U
30
a
-j
ao
May,
1971
10
iol
1 June, 1971
Standard Length (mm)
5
10
IS
Standard Length (mm)
141
Figure 17'
Monthly Standardized Length Frequencies of
Lyopsetta exilis
N
E20
iojj969
10
20
May, 1972
E
20
IS
5
Startdard Length (mm)
JO
2
ii.
5
10
20
15
0
Standard Length (mm)
io(
March, 1971
5
10
15-
20
April, 1971
5
NE
0
5
20
May, 1971
0
04e!97I
0
July, 1971
5
0
10
5
20
Standard Length (mm)
April, 1970
5
IS
I
-J
10
JO
June, 1972
I
5
20
Standard Length (mm)
142
Figure 18
Monthly Standardized Length Frequencies
of Artedius meanyj
July,
E
1971
1969
I
0
15
tO
IS
5
10
'o__March,
April, 1971
to
2
Standard Length (mm)
C
-J
'ci
Feb., 1970
ioi
March, 1970
I
5
0
5
ci
>
I
tI
I
101
2
5
May,1970
I
V.1
5
0
May, 1972
I
1
I
I
ol
5
10
15
June, 1972
I
15
0
0
5
0
15
Standard Length (mm)
5
July,1970
5
0
>
ol
I
June, 1970
5
0
I0
Standard Length (mm)
5
ci April, 1970
E
June, 1971
15
Standard Length (mm)
143
Figure 19
Monthly Standardized Length Frequencies of
Artedius fenestralis
20
E
20
20
July, 969
0
10
March, 972
Jan., 1971
0
5
10
0
5
5
August, 1969
5
10
10
s
15
Standard Length (mm) a
0
10
10
15
10
15
5
10
':'
Standard Length (mm)
July, 1971
May,
to
970
uI
5
10
5
5
10
15
E
June, 1970
0
August, 1971
I5
to
0
May, 1972
10
I
20
6
15
'°
C'J
5
15
M:y,1971
-'i:'
5
10
ApflI, 972
March, 1971
10
10
5
15
Feb., 1971
0
15
July, 1970
August, 1970
5
0
IS
Standard Length (mm)
5
0
15
Standard Length (mm)
144
Figure 20
Monthly Standardized Length Frequencies of
Cyclopteridae Type I
June, 1969
to'____________
('J
I
6
01
Z
01
I
5
tO
5
6201
01
-
July, 1969
I
ol
a,
I>'___
l___
I
6
tol Oct., 1970
-
IS
tO
I
C
20i
I
a
I
5
.J
tO
August,
tOt
,
5
Standard Length(mm)
E201
Z tol
a
20i
5
tO
Feb.,1971
2
I
6
Standard Length (mm)
IS
C
5
0
15
Standard Length (mm)
0
to
Feb.,t970
to
_____
5
tO
March,1970
5
c'.j
5
0
tO
IS
April,1970
5
0
0
15
May, 970
5
10
C
a
5
0
IS
Standard Length(mm)
E
to
May,1971
4,
-J
IS
Standard Length (mm)
June, 1972
10
620
20
22
March, 1971
5
tO
10
I
-j
I5
to
0
5
5
Standard Length(mm)
(J
5
a
IS
I
o
6
Dec., 969
tO
tol April, 972
Standard Length (mm)
969
5
I
a
15
I
I
to' LM0tm 1972
-i
5
10
15
Standard Length (mm)
145
Figure 21a
Progressive Wind Vector Diagrams For 16 April 1969- 31
Dec. 1970.
(From Peterson and Miller, 1975)
/969
EAST
16
JULY
/(IJUN
31 DC
6
APRIL
7
OC
SOUTH
AUG
,J
NOV
/970
I
I
SEPT
/
MAR
EAST
2 PER
I
22 MAY
/
UNE
2OEC
8
JAN
I JULY
SOUTH
!t
26
JULY
I7
-
NOV
SEPT-
OCT
3E
Figure 21 b
Progressive Wind Vector Diagram For I Jan. - 31 Dec. 1971.
(From Peterson and
Miller1
1975)
H
0
C
(I
0
2
C
r
C
fT
(I
lhuubMrlu
or
yvur1u
,ILUIVIIr1,
147
Figure 2! c
Progressive Wind Vector Diagram For I Jan. - 31 Dec. 1972
(From Peterson and Miller, 1975)
C
C
4
C
(I
C
-I
C
r
r
C
Figure 22
Weekly Mean Values of the Coastal Divergence Index ( Bakun's Upwelling Index)
at 45°N 125°W (From Bakun, 1975)
too
I!T1E ti1i 111111k. I,
U)
a
1
0
1 'f
C)
i
E
-100
0
0
-200
a)
9.
too
C)
a,
a)
100
1970
U)
Oh
iii
0
V
-bc
-too
.1,
-20C
.-
too
I
a
-200
tOO
1971
a
0
0
! -too
II
a,
a)
I
-200
-200
IOU
tOO
1972
C)
0
r
I
£
I
I
I
1
I
.
I
I
I
1
1
1
1
I
i
i
I
I
I
r
I
,
I
,
-100
200
Jan.
Feb.
March
April
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Figure 23
Monthly Mean Estimates of Wind Stress Curl Ulelson's Offshore Divergence
Index)
For 1969-1972 At 45°N I25W
(Unpublished Data From 4. Bakun, NMFS)
300
1969
300
200
200
too.
(
00
I
01
0
-tooj
-2001
-100
-300!
200
300
330
1970
200
300
0
200
00
too
0
-too
E
200
200
30
0
0
1300
300
200
100
E
o
0
-100
j-I00
F200
F 300
200
1972
300
200
00
1100
0
10
-1007
300
Jon.
Feb
March
April
May
Jjne
July
Aug
Sept.
Oct.
Nov.
Dec.
a
150
Figure 24
Relative Year-class Strength Estimates For Butter Sole
(Isopsetta isolepis) and English Sole (Parophrys vetulus)
a.) Butter Sole, From 0.D.F.W. Research Exploratory Cruises
50
[11971
401
o
.
o
I
II
301
h
I
II
201
h
ii
I
501
50
4oI1972fl
401
30
30
30
20
20
20
501
1973
969
401 1975
1970
I'
0
I
fi
___
1357
357
___
357
___
357
1972
Age (Years)
No Data From 974. 1971-1973 off Oregon. 1975 off Washington.
b.) English Sole, From 0.D.FW. Commercial Catch Records
0
V
00
1972
1974
I..
S
J1UL.
5
By Forsberg, O.D.EW,
0
Age (Years)
0
z
00
0
Original Calculations
øi
975
1976
50
Ui
No Data
Feb., 1972. Update
100
50
1977
By Barss, O.D.FW.,
Feb., 976.
U,
V
0
5
10
Age (Years)
E
V
50
0
1979
100
0
C
0
III 50c
uIIIIuI!uI!
Age (Years)
Communicated By
R.L. Demory, O.D.F.W.
Oct., 1982.
APPENDICES
151
Appendix I.
Taxa taken in this study, with references containing descriptions, illustrations or
photographs of larvae.
Clupeidae
Clupea harenus pallasi
Valenciennes
Pacific herring
Taylor (1964)
Blackburn (1973)
Marliave (1975)
Engraulidae
Bngraulis inordax Girard
northern anchovy
Bolin (1936)
Ahlstrom (1956, 1965)
Kramer and Ahistrom (1968)
Blackburn (1973)
Osmeridae
Osmerids were not identified to species in this study.
described or illustrated.
Hyponiesus pretiosus (Girard)
Spirinchus thaleichthys
(Ayres)
longf in smelt
Thaleichthys pacificus
(Richardson)
eulachon
The following species have been
Yapchiongco (1941, 1949)
Follett (1952)
Dryfoos (1965)
Moulton (1970)
Barraclough (1964)
Parente and Snyder (1970)
Allosmerus elongacus (Avres), the whitebait smelt, and Spirinchus starksi (Fisk), the night
smelt, have not been described or illustrated as larvae.
Sathylagidse
Bathvlagus ochotensis Schmidt
(No common name)
Ahlstrom (1972)
Paralepididae
Lestidiops ringens (Jordan and Gilbert)
(No common name)
Ege 1953, as
Lestidium elongatum (see Rofen, 1966).
Harry (1953)
Myctophidae
Lampanyctus regalia (Gilbert)
Moser and Ahistrom (1974)
pinpoint lainpfish
Protomyctophum thompsoni
(Chapman)
bigeye lanternfish
Stenobrachius leucopsarus
(Eigenmann and Eigerunann)
northern lampfish
Tarletonbeanja crenularis
(Jordan and Gilbert) = blue lanternfiah
Pereaeva-Ostroumova (1964, 1967)
Moser and Ahlstrom (1970)
Pertseva-Ostroumova (1964, 1967)
Ahlstrom (1965, 1972)
Moser and Ahlstrom (1974)
Bolin (1939)
Pertseva-Ostroumova (1964)
Ahlstrom (1965)
Moser and Ahlstrom (1970)
Gadidae
Microgadus proximus (Girard)
= Pacific tomcod
Matarese et al. (1981)
Scorpaenidae
Sebastes
S rockfish
Eigenmann (1892)
Wales (1952)
Morris (1956)
Delacy et al (1964)
Ahlstrom (1965)
Moser (1967, 1972)
Waldron (1968)
Westrheini et al (1968 a, b)
Efremenko and Liaovenko (1970)
Harling et al (1970)
Westrheim (1975)
152
Appendix I - Continued
Moser et al. (1977)
Moser and Ahlstrom (1978)
Richardson and Laroche (1979)
Laroche and Richardson (1980, 1981)
Hexagraannidae
Ophiodoxt elongatus Girard
lingcod
Blackburn (1973)
Marliave (1975)
Phillips and Barraclough (1977)
Cottidae
All of the sculpin taxa taken in this atudy have been described by Richardson and Washington
(1980), and Washington (1982).
Artedius harringtoni (Starks)
scalyhead sculpin
Artedius fanestralis Jordan
and Gilbert
padded sculpin
Artedius meanyi (Jordan and Starks)
Puget Sound sculpin
Clinocottus acuticeps (Gilbert)
sharpnose sculpin
Cottus
Richardson
= prickly sculpin
Enophrys bison
buffalo sculpin
Hemilepidotus hemilepidotus
(Tilesius)
red Irish lord
Hemilepidotus spinosus (Ayres)
brown Irish lord
Leptocottus armatus Girard
= Pacific staghorn sculpin
Scorpaenichthys marmoratus
(Ayres) = cabezon
Blackburn (1973), as "cottid 6'
Eldridge (1970), as "cottid no. 4"
Blackburn (1973), as"cottid 4, water wings'
White (1977), as "cottid III"
Blackburn (1973), as "cottid 3"
Blackburn (1973), as "cottid 1, biramous
anus"
Blackburn (1973)
Stein (1972)
Blackburn (1973)
Marliave (1975)
Misitano (1978)
Gorbunova (1964)
Peden .(1978)
Follett (1952)
Peden (1978)
Jones (1962)
Blackburn (1973)
Marliave (1975)
White (1977)
O'Connell (1953)
Marliave (1975)
Radulinus asprellus Gilbert, the slim sculpin, and the larvae referred to in this study as
cottids type ic, type 20 and other Cottidae were described by Richardson and Washington (1980)
Agonidae
Pallisina barbata (Steindachner)
= tubenose poacher
Marliave (1975)
Bathyaonus5pp., Ocella verrucosa (Lockington), the warty poacher, Odontopyxis trispinosa
(Lockington), the pygmy poacher, and Stellerina xyosterna (Jordan and Gilbert), the prickle
breast poacher, were taken in this study.
Their larvae have not been described. Marliave
(1975) presented illustrations of other larval agonids.
Cyclopteridae
Liparid type 1, in this study, is probably a multi-species group (Richardson and Pearcy,
1977).
Marliave's illustrations of larval Liparis fucensis resemble liparid type 1
(Marliave, 1975).
Liparis puichellus Ayres, the showy snailfish, and liparid type 3 from this study have not
been described or illustrated as larvae.
Bathvmasteridae
Ronguilus jordani (Gilbert)
northern ronquil
Bathymasterid larvae were discussed by
Blackburn (1973)
A blennioid larva taken in this study was not identifiable to family.
or illustrated.
Stichaeidae
Anoplarchus spp.
= cockscomb
Blackburn (1973)
Marliave (1975)
It has not been described
153
Appendix I - Continued
Chirolophus spp.
Blackburn (1973)
Poroclinus rothrocki Bean, the whitebarred prickleback, and Stichaeidae type 3 of this study
have not been described or illustrated.
Pholidae
Pholis spp.
gunnel
Blackburn (1973)
Marliave (1975)
mmodytidae
mmodytes hexapterus Pallas
Blackburn (1973)
= Pacific sand lance
See Macer (1967) for illustrations of larval Amiodytes.
Gob iidae
Clevelandia los (Jordan and Gilbert)
= arrow goby
Prasad (1959)
Larvae of Lepidogobius lepidus (Girard), the bay goby, have not been described or illusated.
Centrolophidae
Icichthys lockingroni Jordan and Gilbert
inedusafish
Ahls tram et al. (1976)
Bothidae
Citharichthys sordidus
(Girard)
Pacific sanddab
Citharichthys stigmaeus Jordan and Gilbert
speckled sanddab
Pleuronectidae
Glyptocephalus zachirus
Lockington = rex sole
Hippoglossoides elassodon
Jordan and Gilbert
flathead sole
Isopsetta isolepis (Lockingron)
butter sole
Lepidopsetta bilineata
(Avres)
rock sole
Lyopsetta exilis (Jordan and Gilbert)
= slender sole
Microstoinus pacificus
(Lockingron)
Dover sole
Parophrvs vetulus Girard
Ahlstrom (1965)
Ahlstrom and Moser (1975)
Porter (1964)
Ahlstroni (1965)
Ahlscrom and Moser (1975)
Porter (1964)
Ahlstroin and Moser (1975)
Dekhnik (1959)
Pertseva-Ostroumova (1961)
Miller (1969)
Alderdice and Forrester (1974)
Forrester and Alderdice (1968)
Levings (1968)
Blackburn (1973)
Richardson et al. (1980)
Pertseva-Oscroumova (1961)
Blackburn (1973)
Blackburn (1973)
Ahlstroin and Moser (1975)
Hagernan (1952)
Ahistrom and Moser (1975)
Budd (1940); the 6.3 mm larva is mis-
identified
Orsi (1968)
Blackburn (1973)
Ahlstroni and Moser (1975)
Misitano (1976)
Richardson et al. (1980)
Porter (1964) described Parophrys larvae. However, his discussion and photographs of this
species include specimens of Psetti.chthys inelanosticrus.
Platichthys stellatus (Pallas)
Orcutt (1950)
starry flounder
Psettichthys melanostictus
Girard = sand sole
Yusa (1957)
Pertseva-Ostroumova (1961)
Hickman (1959)
Porter (1964); some Psettichthys are
misidentified as Parophrvs
Sonimani (1969)
154
Appendix II
Species taken, number of specixens of each species, number of sample dates on which each species
was taken, total standardized abundance (E nimiber/lO a2 of sea surface) of each species, percent
of total catch of each species, percent of standardized abundance of each species, and biological
index for each species.
Species
Sample
Total
Standardized
S of
Total
S of
Standardized
Dates
Abundance
Catch
Abundance
10
5
31.95
0.18
0.24
0.04
8
5
24.32
0.15
0.18
0.03
2961
101
5732.58
54.13
42.31
1.61
ochotensis
3
2
6.54
0.06
0.06
0.00
Lea tidiops
ringens
1
1
6.68
0.02
0.05
0.02
1
1
1.17
0.02
0.01
0.00
1
1
5.64
0.02
0.04
0.01
21
11
104.51
0.38
0.77
0.11
crenularja
1
1
2.00
0.02
0.01
0.02
Microgadus
proximus
184
51
482.77
3.36
3.56
0.45
Sebastes spp.
183
37
702.72
3.34
5.19
0.47
7
7
26.16
0.13
0.19
0.03
117
50
390.35
2.14
2.88
0.48
59
29
149.36
1.08
1.10
0.25
meanyi
76
26
158.59
1.39
1.17
0.15
Clinocottus
acuticeps
27
15
50.07
0.49
0.37
0.11
40
15
81.89
0.73
0.60
0.11
21
12
77.19
0.38
0.57
0.07
9
4
16.78
0.15
0.12
0.10
27
12
68.43
0.49
0.51
0.09
4
4
15.84
0.07
0.12
0.03
6
6
25.21
0.11
0.19
0.05
No.
of
Specimens
Clupea
harengus
No. of
Biological
Index
Engraulis
inordax
Osmeridae
Bathylagus
Lampanyctus
regalis
Pro tomvctophum
thoinpsoni
S tenobrachius
leucopsarus
Tarletonbeania
Ophiodon
elongarus
Artedius
harringtoni
Artedius
fenestralis
Artedius
Cottus
Enophrys
bison
Hemilepidotus
hemilepidotus
Hemilepidotus
apinosus
Leptocottus
armatus
Padulinus
asprellus
155
Appendix II - Continued
Species
No. of
No. of
% of
Biological
Sample
Total
Standardized
% of
Specimens
Total
Standardized
Index
Dates
Abundance
Catch
Abundance
Scorpaenichthys
marnioratus
3
3
9.48
0.05
0.07
0.01.
Cottjdae lc
4
4
9.70
0.07
0.07
0.01
Cottidae 20
1
1
3.68
0.02
0.03
0.00
Other Cottidae
5
4
11.04
0.09
0.08
0.04
xvosterna
9
7
31.80
0.16
0.23
0.07
Bathvagonus app.
1
1
2.45
0.02
0.02
0.002
1
1
2.77
0.02
0.02
0.00
1
1
6.91
0.02
0.05
0.02
1
1
1.94
0.02
0.01
0.01
24
23
115.34
0.44
0.85
0.15
7
6
29.38
0.13
0.22
0.03
13
6
22.46
0.24
0.17
0.07
3
5
16.56
0.09
0.12
0.06
1].
9
33.97
0.20
0.25
0.09
1
1.
4.10
0.02
0.03
0.07
iioplarchus spp.
3
2
2.88
0.05
0.02
0.004
Chirolophis spp.
18
6
42.36
0.33
0.31
0.02
2
2
4.48
0.04
0.03
0.005
2
1
4.22
0.04
0.03
0.005
13
10
35.95
0.24
0.27
0.02
109
20
346.70
1.99
2.56
0.24
2
2
7.96
0.04
0.06
0.03
1
1
1.89
0.02
0.01
0.002
1
1.
1.22
0.02
0.01
0.001
1
1
3.14
0.02
0.02
0.02
Stellerina
Pallisina
barbata
Odontopyxis
trispinosa
Ocella
verrucosa
Cyclopteridae
Type No. 1
Liaris
pulchellus
Cyclopteridae
type No. 3
Other
Cyclopteridae
Ronguilus
jordani
Unidentified
Blennioids
Poroclirtus
rothrocki
S tichaeidae
Type 3
Pholis spp.
ziodytes
hexapterus
Clevelandia
ice
Lepidogobius
lepidus
Icichthys
lockingroni
Citharichthys
sordidus
156
Appendix II - Continued
Species
o. of
to. of
Total
2 of
% of
Biological
Specimens
Sample
Standardized
Total
Standardized
Index
Dates
Abundance
Catch
Abundance
Citharichthys
stigmaeus
2
2
8.93
0.04
0.07
0.02
Clvptocephalus
zachirus
3
3
12.07
0.05
0.09
0.02
12
3
26.62
0.22
0.20
0.04
491
60
1524.35
8.98
11.25
0.88
1
1
2.54
0.02
0.02
0.00
83
2].
186.16
1.52
1.37
0.16
pacificus
3
3
14.90
0.05
0.11
0.16
Parophrys
vetulus
498
55
1923.88
9.10
14.20
0.83
99
23
296.28
1.81
2.19
0.21
272
42
637.12
4.97
4.70
0.41
Hippoglossoides
elassodon
Isopsetta
isolepis
Lepidopsetta
bilineata
Lyopsetta
exilis
Micros tomus
Platichthvs
stellatus
Psettichthys
melanostictus
157
Appendix III
Total Standardized Abundances of all Species at each Station for each date.
NH 1
NH 3
NH 5
NH 10
Total
22
0.00
0.00
20.61
9.32
29.93
7.48
29
2.30
6.11
--
--
8.41
4.21
--
IDate
Mean
1969
June
July
August
Sept.
10
5.36
74.60
8.55
88.51
29.50
18
12.71
23.75
0.00
0.00
36.46
9.12
25
12.05
15.69
0.00
0.00
27.74
6.94
30
--
--
-
0.00
0.00
0.00
0.00
0.00
134.42
33.61
6
1.38
0.00
0.00
0.00
1.38
0.35
30
11.13
19.44
24.99
31.77
87.33
21.83
3
22.76
6.91
24.52
0.00
54.19
13.55
--
0.00
0.00
--
0.00
0.00
0.00
4.31
0.00
0.00
4.31
1.08
--
0.00
0.00
--
0.00
0.00
23
0.00
0.00
2.00
0.00
2.00
0.50
29
0.00
0.00
0.00
9.88
9.88
2.47
11
0.00
0.00
6.28
0.00
6.28
1.57
18
0.00
52.14
81.62
43.20
176.96
44.24
2
2.00
39.52
17.94
64.40
123.86
30.97
9
2.27
6.53
27.16
--
35.96
11.99
29
5.74
6.68
17.07
33.10
62.59
15.65
13
49.45
--
--
49.45
49.45
29
81.90
95.89
39.52
21.32
238.63
59.66
13
246.44
208.28
25.92
407.43
888.07
222.02
19.69
28
Nov.
Dec.
122.74
26
14
Oct.
11.68
8
1970
Jan.
Feb.
--
25
3.06
37.38
10.92
27.40
78.76
March
9
75.24
45.98
126.73
89.65
337.60
84.40
April
16
--
393.60
393.60
27
0.00
1
4.44
May
--
-
1.69
34.24
7.02
42.95
10.74
151.84
7.52
0.00
163.80
40.95
393.60
6
3.60
149.76
7.60
0.00
160.96
40.24
22
79.54
84.36
51.45
20.22
235.57
58.89
4
.0.00
9.25
21.96
31.21
10.40
23
4.80
3.92
0.00
0.00
8.72
2.18
2
13.38
12.81
10.68
4.10
41.17
10.29
16
6.1.4
2.89
8.40
4.20
21.93
5.48
29
0.00
4.96
2.25
0.00
7.21
1.80
August 13
9.90
0.00
5.49
0.00
15.39
3.85
27
0.00
0.00
0.00
0.00
0.00
0.00
11
5.80
2.12
0.00
0.00
7.92
1.98
25
12.46
1.66
0.00
0.00
14.12
3.53
9
0.00
0.00
1.11
0.00
1.11
0.28
20
5.81
5.19
0.00
2.44
13.44
3.36
June
July
Sept.
Oct.
--
158
Appendix III - Continued
Date
NH 1
NH 3
NH 5
NH 10
Total
1970
Nov.
4
4.89
0.00
0.00
0.00
4.89
Dcc.
4
2.41
0.00
0.00
0.00
2.41.
0.50
21
3.44
16.62
4.74
46.76
71.56
17.89
20.98
1.22
1971
Jan.
6
11.82
7.84
34.65
29.60
83.91
18
1.87
104.04
0.00
0.00
105.91
26.48
3
141.86
290.36
97.06
26.70
555.98
139.00
16-17
24.96
Feb.
125.28
272.48
18.60
441.32
110.33
20
--
35.04
217.80
42.84
295.68
98.56
30
28.08
14.90
56.10
23.66
122.74
30.69
--
--
36.72
7.24
43.96
21.98
3-4
89.54
411.60
81.76
203.87
786.77
196.69
14-20
33.24
404.55
99.75
62.30
599.84
149.96
29-2
9.00
777.48
450.66
90.24
1327.38
331.85
June 12-13
57.50
282.20
1118.38
21.60
1479.68
369.92
28-30
4.65
155.93
22.15
813.12
995.85
248.96
52.21
March
April 2.2-26
May
July
6
41.60
104.26
63.00
0.00
208.85
21-22
58.14
32.69
0.00
0.00
90.83
22.71
August 2-3
24.87
15.39
0.00
6.97
47.23
11.81
3.05
19-20
0.00
0.00
12.20
0.00
12.20
Sept. 23-24
0.00
3.40
0.00
0.00
3.40
0.85
Oct. 11-12
0.00
0.00
57.72
12.34
70.06
17.52
Nov.
6-7
3.20
13.32
0.00
0.00
16.52
4.13
Dec.
7
3.14
49.92
33.60
38.71
125.37
31.34
99.50
1972
March 3-4
62.44
308.36
27.18
0.00
397.98
15-16
52.78
41.58
20.04
6.41
120.81
30.20
29-30
97.96
--
145.39
16.23
259.58
86.53
25.22
April
11
57.13
12.64
15.24
15.87
100.88
21-22
49.64
--
81.48
0.00
131.12
43.71
May 22-23
170.10
403.68
301.92
0.00
875.70
218.93
June 11-12
12.66
17.60
18.32
10.12
58.70
14.68
28-29
22.99
43.40
40.60
6.88
113.87
28.47
July 21-22
1.69
3.98
4.84
0.00
10.51
2.63
28.14
12.65
13.60
0.00
54.39
13.60
August
5