AN ABSThAC OF THE IHESIS OF
Willard Waldo Wakefield
in
Oceanography
Title:
for the degree of
presented on
Master of Science
February 6, 1984
FEEDING RELATIONSHIPS WITHIN ASSEMBLAGES OF NEARSHORE
AND MIDCONTINENTAL SHELF I3ENTHIC FISHES OFF OREGON
Abstract approved:
Redacted for Privacy
,.
Prof. H. F. Frolander
The food habits of 22 species of benthic fishes occurring on
the Oregon continental shelf were investigated from specimens
collected by trawling nearshore (9 and 22 m sta.) and midshelf
(73 m sta.) depths during spring 1979.
Two generalized feeding types were identified:
fishes that
prey solely on pelagic crustaceans and fishes, and fishes that
feed on infaunal invertebrates, including polychaetes, nemerteans,
amphipods, cumaceans and molluscs.
In the nearshore environment, pelagic and/or epifaunal
feeders included Psettichthys melanostictus (sand sole) which
dominated the catch numerically, Citharichthys stigmaeus (speckled
sanddab), Microgadus proximus (Pacific tomcod), Spirinchus starksi
(night smelt), and Allosmerus elongatus (whitebait smelt).
These
fishes fed mainly on crustaceans; with mysids composing 40% of the
weight of their stomach contents.
Diet overlap was intermediate
to high within this predator group, ranging from 22 to 73%.
Within the same assemblage, epifaunal and/or infaunal feeders were
Rala binoculata (big skate), Hydrolagus colliei (ratfish),
Platichthys stellatus (starry flounder), Isopsetta isolepis
(butter sole), and Parophrys vetulus (English sole).
R.
The skate,
binoculata, ranked first in biomass, and together with H.
colliei, fed largely on Cranon stylirostris and Cancer magister.
Ammodytes hexapterus (sand lance) and juvenile
also important in the skate's diet.
.
stigmaeus were
Parophrys vetulus had the
most diverse diet, feeding primarily on infaunal polychaetes,
Epibenthic invertebrates
amphipods, nemerteans, and cumaceans.
were more important in the diets of
than in the diet of P. vetulus.
.
stellatus and I. isolepis
Diet overlap within this group
ranged from low to intermediate ranging from 1 to 37%.
At the midshelf site, both Citharichthys sordidus (Pacific
sanddab), the most abundant species, and Eopsetta .iordani (petrale
sole), fed on or above the substrate, but C. sordidus fed more on
pelagic prey.
Citharichthys sordidus consumed euphausiids,
copepods, pteropods, a pelagic mysid and salps.
shift was observed in the diet of E.
A size related
jordani with small
individuals preying on mysids, Crangon, and newly settled
pleuronectiforms, and larger individuals feeding on larger
juvenile pleuronectiforms.
Six common species of pleuronectiforins
at this site were found to feed on a mixture of epibenthos and
infauna.
Four, P. vetulus, Microstomus pacificus (Dover sole),
Glyptocephalus zachirus (rex sole), and I.
isolepis fed
primarily, but in varying degrees, on polychaetes and amphipods.
Polychaetes were the only prey of Pleuronichthys decurrens
(curifin sole).
The remaining pleuronectid, Lepidopsetta
bilineata (rock sole), preyed on recently settled
pleuronectiforms, Crangon, and amphipods.
Within these six
flatfishes, diet overlap ranged from 0 to 28%.
To siimmarize the trophic relationships within the assemblages
inhabiting the two continental shelf areas, two food webs were
constructed, combining information from both the literature and
the current study.
FEEDING RELATIONSHIPS WITHIN ASSEMBLAGES OF NEARSHORE
AND MIDCONTINEZ4TAL SHELF BE24ThIC FISHES OFF OREGON
by
Willard Waldo Wakefield
A THESIS
submitted to
Oregon State University
in partial fulfillment of
the requirements for the
degree of
Master of Science
Completed February 6, 1984
Commencement June 1984
APPROVED:
Redacted for Privacy
Professor of Oceanography in charge of major
Redacted for Privacy
Dean of College of Oceanography
Redacted for Privacy
Dean of Gra'iite School
Date thesis is presented
February 6, 1984
Typed by Waldo Wakefield for
Willard Waldo Wakefield
ACKNOWLEDGE1IENTS
I gratefully thank my committee members Drs. Herbert
Frolander, William Pearcy, Carl Bond, and Robert Morris.
A
special thanks belongs to Dr. Pearcy for his guidance and support
throughout the various stages of this thesis.
Dr. Al Tyler
participated as my minor professor in the earlier stages of the
research.
Dr. Ellen Pikitch provided helpful criticism during the
final stages.
Many individuals, outside my committee have helped me along
the way, and I would like to acknowledge as many as possible.
A group of fellow graduate students in my "year class"
provided a supportive environment for learning and living, in
particular, Chip Hogue, Kathy Fisher, Marc Willis, Hal Batchelder,
Dave Strehlow, and Tom DeYries.
The field samples were collected from two commercial fishing
vessels. Credit goes to the captain and crew of the M/V MiToi and
M/V Olympic.
Two 24 hour sampling efforts at sea were made
possible, because of the hard work of Chip Hogue, Wayne Laroche
and Andy Rosenberg in May, and Wendy Gabriel, Mary Yokiavich,
Betsy Washington, Marc Willis and Andy Rosenberg in August.
Howard Jones and Jamie Trautman donated a great deal of time
to help with polychaete and amphipod taxonomy.
Dr. Robert Olson
identified gut parasites, and provided interesting discussion on
fish parasitology.
Dr. Andrew Carey and Howard Jones provided unpublished data
from Moolack Beach box core samples.
A number of close friends within the OSU Oceanography
community, not previously mentioned, added to my graduate
education experience, Joanne Laroche, Bruce Mundy, Joe and
Madeline Fisher, Bill Peterson, Dave Stein, Barb Dexter, Dena
Gadomski, Jim Harvey, Robin Brown, Denise Herzing, Rebecca
Simpkins, Rick Brodeur, Jon Shenker, John Kern, and John Kalish.
Dr. Charlie Miller, a good friend and exceptional teacher,
greatly enriched my learning experience in the field of Biological
Oceanography.
Andy Rosenberg, and Chip and Barbry Hogue saw me through good
and bad times, and I could not have completed this work without
them.
To Clare, thanks for your loving support in these recent
years.
To my parents, thanks for all that you have given me.
This research was sponsored by Oregon State University Sea
Grant College Program supported by NOAA, Office of Sea Grant.
TABLE OF CONTENTS
Page
ThThOD1JCION. 1
SAMH.. ING AREA AND METHODS
.3
Sampling Area and Program ................................. 3
Laboratory Methods ........................................ 7
Data Presentation and Diet Overlap Index .................. 8
RESULTS .................................................... 11
Species Composition ...................................... 11
Bicimass .................................................. 15
Length Frequency ...........................................
Food Habits ..............................................
9 m Station ..........................................
22 m Station .........................................
73 m Station .........................................
SizeRelated Trends ..................................
Diet Similarity ......................................
Prey Availability ....................................
17
17
23
29
34
41
45
51
DISCUSSION ...................................................
Fish Assemblages .........................................
Food Habits ..............................................
The Food Habits of Nearshore Benthic Fishes ..........
The Food Habits of Midshelf Benthic Fishes ..........
Trophic Relationships ....................................
Concluding Remarks .......................................
57
57
59
61
63
65
71
BIBLIOGRAPHY ................................................. 73
APPENDICES ................................................... 78
LIST OF FIGURES
Figure
Page
1
Trawl tracks for May and August 1979
2
Average percent composition by weight of trawl
catch at three depths off Moolack Beach
16
3
Frequency distribution of lengths for fishes
collected at the 9 m station during May 1979
18
4
Frequency distribution of lengths for fishes
collected at the 22 m station during May 1979
19
5
Frequency distribution of lengths for fishes
collected at the 73 m station during May 1979
20
6
Cumulative number of prey taxa as a function
of number of stcinach samples analyzed for
fish species
22
7
Diagram of benthic food web in the nearshore
area off Moolack Beach, Oregon
67
8
Diagram of benthic food web in the
midcontinental shelf area off Moolack Beach,
Oregon
69
4
LIST OF TABLES
Tables
1
Page
Trawl and catch information for May and August
6
1979
2
Summary of overall species composition and
ranking of 10 most numerically abundant fishes
captured during May 1979
12
3
Summarization of the number of each fish
species examined, proportion of empty
stanachs, and stcinach fullness by station
21
4
Average percent composition by weight of major
prey (weights of lower taxa summed) in the
diets of fishes collected at the 9 m station
off Moolack Beach, Oregon, May 1979
24
5
Percent frequency of occurrence (FO), and
average percent composition by weight (W)
and numbers (#) of principal prey for
pelagic and/or epifaunal feeding fishes
collected at the 9 m station (May 1979)
26
6
Percent frequency of occurrence (FO), and
average percent composition by weight (W)
and numbers (#) of principal prey for
epifaunal and/or infaunal feeding fishes
collected at the 9 m station (May 1979)
27
7
Average percent composition by weight of major
prey (weights of lower taxa summed) in the
diets of fishes collected at the 22 m station
off Moolack Beach, Oregon, May 1979
30
8
Percent frequency of occurrence (FO), and
average percent composition by weight (W)
and numbers (#) of principal prey for
pelagic and/or epifaunal feeding fishes
collected at the 22 m station (May 1979)
31
9
Percent frequency of occurrence (FO), and
average percent composition by weight (W)
and numbers (#) of principal prey for
epifaunal and/or infawial feeding fishes
collected at the 22 m station (May 1979)
32
Average percent composition by weight of major
prey (weights of lower taxa summed) in the
diets of fishes collected at the 73 m station
off Moolack Beach, Oregon, May 1979
35
10
11
Percent frequency of occurrence (FO), and
average percent composition by weight (W)
and numbers (#) of principal prey for
pelagic and/or epifaunal feeding fishes
collected at the 73 m station (May 1979)
36
12
Percent frequency of occurrence (FO), and
average percent composition by weight (W)
and numbers (#) of principal prey for
epifaunal and/or infaunal feeding fishes
collected at the 73 m station (May 1979)
39
13
Percent frequency of occurrence (FO), and
average percent composition by wet weight
42
('WT) of dominant prey in stcinachs of
Psettichthys melanostictus less than or
equal to and greater than 200 mm standard
length (SL)
14
Percent frequency of occurrence (FO), and
average percent composition by wet weight
(WT) of dominant prey and parasitic Trelatoda
(Otodistomum velipoum) in stcinachs of
Raia binoculata grouped into four length
stanzas: standard length (SL mm) < 400 (193
398), 400
599, 600
799, > 800 (870
1320)
44
15
Percent frequency of occurrence (FO), and
average percent composition by wet weight
(WT) of dominant prey in stcinachs of
Eopsetta jordani less than and
greater than 200 mm standard length (SL)
46
16
Similarity in the diets of eight species of
fish collected at the 9 m station based on
percentage of major taxa in their diets on a
wetweight basis, and on percentage of taxa
identified to the lowest taxoncmiic unit
(usually species)
47
17
Similarity in the diets of ten species of
fish collected at the 22 m station based on
percentage of maj or taxa in their diets on a
wetweight basis, and on percentage of taxa
identified to the lowest taxonxiic unit
(usually species)
48
18
Similarity in the diets of eleven species of
fish collected at the 73 m station based on
percentage of major taxa in their diets on a
wetweight basis, and on percentage of taxa
identified to the lowest taxoncinic unit
(usually species)
49
19
Numerical abundance and average composition
of invertebrates in box core samples from
22 m station
52
20
Abundance of invertebrates and fishes in beam
trawis at the 22 m station off Moolack Beach
on 2 and 29 May 1979
54
FEEDING RELATIONSHIPS WITHIN ASSEMBLAGES OF NEARSHORE
AND MIDCONTINENTAL SHELF BENTHIC FISHES OFF OREG(4
IN TR ODE cr ION
There is increasing interest in the field of fisheries to go
beyond single species management and to consider entire fish
assemblages in areas where mixed species fisheries predominate
(Gulland, 1977; Tyler, Gabriel and Overholtz, in press). On the
basis of species composition, Gabriel (1983) identified seventeen
regional fish assemblages for the mid to outercontinental shelf
and upper slope along the west coast of the United States for the
area extending from Cape Blanco, Oregon to Cape Flattery,
Washington.
The Oregon groundfish fishery targets a number of
different nearshore, mid and outer continental shelf assemblages
that include mixtures of pleuronectiforms (flatfishes),
scorpaenids (rockfishes), and Anoplopoma fimbria (sablefish)
(Gabriel and Tyler, 1980).
Eight major pleuronectid species are
harvested off Oregon, accounting for over 40% of the annual trawl
landings (Jackson, 1981).
The group of pleuronectiform fishes was
selected for studies of their ecology off Oregon by investigators
involved in the project, "Pleuronectid Production System and its
Fishery", sponsored by Oregon State University Sea Grant.
Management of multispecies fisheries requires information on
the biology of members of the assemblage, in particular, knowledge
of potential interactions among all commercial and noncommercial
fishes within a given assemblage.
A first step is to describe the
trophic structure of these fish assemblages.
Three recent studies
2
have examined feeding relationships within pleuronectid
assemblages on the mid and outer continental shelf off Oregon
(Kravitz et al., 1977; Pearcy and Hancock, 1978; and Gabriel and
Pearcy, 1981).
However, they have not examined food habits of
cooccurriung, nonpleuronectid fishes within the area studied.
In addition, little work has been done in nearshore, open coast
areas off Oregon.
The objectives of this study were to:
1) characterize fish assemblages inhabiting a nearshore and
midshelf area off Oregon,
2) describe and compare the food habits of fishes belonging
to these assemblages,
3) identify potential pleuronectiform predators, and
4) construct a partial food web in an attempt to summarize
important fish feeding interactions on the continental
shelf.
I report here the results of this study, and summarize the
knowledge of trophic relationships of fishes important
commercially and ecologically on the Oregon continental shelf.
3
SAMPLING AREA AND METhODS
Sampling Area and Program
The study area lies off Moolack Beach on the central Oregon
Continental shelf (Figure 1).
This site was one of several
selected for studies by investigators involved in the project,
"Pleuronectid Production System and its Fishery". Previous work
in the Moolack Beach nearshore has focused on recruitment, growth,
and feeding ecology of juvenile pleuronectids in an open coast
nursery ground (Jackson, 1981; Rosenberg, 1982; Hogue and Carey,
1982; and Krygier and Pearcy, unpubl. manuscr.).
Stations reported here were sampled in the nearshore at
depths of 9 and 22 in,
and at a midshelf depth of 73 in.
The 9 and
22 m stations are separated bathymetrically by a rock reef that
rises from a depth of 15
in to 6 in
below the sea surface and
extends from Cape Foulweather to Yaquina Head.
The sediments in
this shelf area consist of fine sands that decrease in mean grain
size offshore (Roush, 1970 and
content at midshelf
(50
Kuhn et al.., 1975).
70 in)
A greater mud
is attributed to increased
sedimentation of fines and bioturbation as evidenced by burrowing
in the sediments (Kuhn et al., 1975).
Fishes were collected on two dates utilizing two types of
commercial trawls.
An Atlantic Western IVA otter trawl was
fished from the dragger F/V Mi Toi on 20 May 1979.
This trawl was
constructed of 12.7 cm mesh (all mesh measurements are stretch
mesh) in the belly and lower half of the wings, and 20.3 cm mesh
in the square and upper half of the wings.
A 29 mm mesh liner was
(Pau/wec//er
I
/
/
L6Cm0
44°45 N4
x
(/11.!
N
440 4Q
ewp
I
I
124°15W
I
I
i
if /ILI.
124°IO
Figure 1. Trawl tracks for May and August 1979.
124005
sewn into the cod end to facilitate retention of juvenile fishes.
This 24 m foot rope trawl was assumed to have a 12 m spread
between the wings (assuming that spread equals 1/2 foot rope
length (Dennis Lodge, pers. comm.)).
Rubber disc lower bridles
and hose wrapped tow lines increased the effective fishing width
by herding fishes into the trawl's path (Henunings, 1973; Main and
Sangster, 1981).
Paired 27.4 m shrimp box trawls were fished from
the 25.9 m shrimper F/V Olympic on 6 August 1979.
This shrimp
trawl was constructed of 38 mm mesh throughout the body and the
wings.
A 29 mm mesh cod end liner was sewn into the cod end.
The 27.4 m foot rope was assumed to have an effective fishing
width of 13.7 m (again, assuming that spread equals 1/2 foot rope
length).
The bridles and tow lines of a shrimp trawl are not
designed to herd fish as in an otter trawl.
In addition, shrimp
trawls are not designed to fish on the bottom.
For this reason,
chain ballast was added to the leadline so that it dragged along
the bottom.
On each sampling date, single tows were made during day and
night at each station.
On 20 May a duplicate tow was made at the
22 m station to investigate tow to tow variability.
Tow duration
was 20 and 30 minutes in May and August, respectively.
Loran C
position fixes at the beginning and end of each tow were used to
measure relative distance covered during each tow.
These
distances agreed with estimates based on tow times plus ship's
speed.
Tow distances ranged from 1330 to 1590 m in May, and 620
to 1750 m in August (see Table 1 for a summary of trawling
information).
Table 1.
Trawl and catch information for May and August 1979.
STATION
73m
22m
9iri
night
day(1)
y(2)
night
night
DAY (hrs)
1600
0333
1324
0048
1852
1000
2255
AREA SAMPLED (m2)
19190
16710
17953
16890
17110
18520
15970
272
905
641
672
922
2352
586
53
147
149
129
475
138
41
(his)
0855
0358
1622
-
0040
1848
2210
AREA SAMPLED (m2)
26820
16940
55040
-
33880
35280
48000
33
28
7
-
11
43
57
TIME OF
NO. FISH
BIOMASS (g/10 m2)
AUGUST
TIME OF DAY
TOTAL BIOMASS
(g/10 m2)
7
The entire catch was sorted into baskets by species.
The
catch of each species was counted (May only) and then weighed on a
45 kg capacity spring scale.
A subsample of fishes less than 300
mm standard length (SL) was promptly preserved in 10% buffered
formalin at the time of capture.
The coelom of fish greater than
150 mm were opened to enhance preservation of stomach contents.
The stomachs of most individuals greater than 300 mm
removed at sea and preserved in buffered formalin.
(SL) were
Each stomach
had a label which included information on tow number, species and
fish length.
Fish biomass estimates were calulated from catch weights
determined at sea,
t
distances, and estimates of the effective
fishing width of the trawls.
Laboratory Methods
Stomach contents were analyzed for the May cruise only.
Prior to laboratory examination, all fish subsamples were
transferred to 40% isopropyl alcohol.
In the laboratory, fish
were selected randomly from these subsamples and standard lengths
were taken on a maximum of fifty fish.
From these same fish,
stomach contents were examined (contents anterior to the pyloric
valve).
Stomachs were ranked according to fullness:
2/3, 3/3 full to distended.
empty, 1/3,
Food items were identified to species
whenever possible, or when not possible, to the lowest taxa
practical, and counted.
In making counts on fragmented organisms,
only fragments representing whole prey were counted; for example,
polychaete heads, mysid telsons, ophiuroid discs, etc.
As a
measure of prey quantity, each prey taxon was grouped, blotted,
and weighed to the nearest 0.01 g (wetpreserved weight) on a
Mettler balance.
Prey that were too small to be weighed
individually were assigned wetpreserved weights derived from
weighing a number of similar sized individuals of the taxon in
question.
In many instances, stomachs contained prey fragments
and well digested prey that could not be identified.
This
material was grouped together under the category of unidentified
material, and weighed.
The proportion of unidentified material is
included at the bottom of each principal prey or complete diet
summary table.
Although wetweights for molluscs and echinoderms
may overestimate nutritional value when compared to those for
crustaceans and softbodied prey, no correction was attempted.
A
range for total length was taken for each invertebrate prey taxon
for each fish stomach (carapace width for brachyurans).
Standard
lengths (SL) were taken on all fish prey.
Data Presentation and Diet Overlap Index
A diet summary table for each station was constructed by
combining (summing) the wetweight percent composition of lower
taxa under major taxonomic headings (usually class or order).
addition, the species composition of principal prey taxa (FO >
15%) in the diet of each fish species at each station was
summarized as percent frequency of occurrence (FO), average
percent wetpreserved weight, and average percent numeric
abundance.
A complete diet summary appears in the appendices.
In
Percent similarity as a measure of dietary overlap was
calculated using the index described by Whittaker (1952) (see
also, Bray and Curtis, 1957) for predators A and B as:
percent similarity (PS) = l0Omin (at, b)
where
and b are the percent wetpreserved weight for the ith
a1
prey taxa in the diets of fish species A and B, respectively, and
s is the total number of prey taxa in the diets of predators A and
B.
Percent similarity is a biased statistic, which tends to
underestimate similarity. The bias decreases with increasing
sample size and decreasing diversity of the population (Miller,
1970).
Diet similarity was calculated in two ways:
on the basis
of comparisons made at the major taxa level (eg. polychaete,
amphipod, etc.) and at the lowest taxonanic unit level (usually
species).
In calculating percent overlap, if some prey were only
identified to higher taxonomic levels due to advanced state of
digestion, then infOrmation on true proportions of different types
of prey will be lost, and errors in percent overlap will result.
This potential error was overcome by apportioning of the total
wetpreserved weight contributed by the higher taxa prey among
lowest taxoncinic units within that taxon.
The weight contribution
of these unidentified higher taxa was apportioned according to the
relative weights of the lower taxa identified from stomachs of a
given fish species on a sampling date. The following example
illustrates how prey that could not be identified to lower
10
tazonanic levels was apportioned to lower taxonnic levels:
unapportioned
%WT
Polychaeta
Capitellidae
Spiochaetoiterus costarum
Cirratulidae
Chaetozone setosa
Nephtydae
Nephtys sp.
22.5
8.7
2.7
6.5
total %
apportioned
%WT
22.0
3.0
18.4
3.2
6.2
46.6
46.6
11
RESULTS
Species Composition
A total of 6350 fishes representing 34 species were collected
in seven tows off Moolack Beach during May (only species
composition by weight was taken for August).
Average species
richness (number of species) in collections at the 22 m station
was higher (18.3) than at the 9 m or 73 m station (10.5 and 14.0,
respectively) (Table 2).
The ranks of the 10 most numerous fishes captured in each tow
during May (Table 2) show that Psettichthys melanostictus (sand
sole), was usually numerically dominant at the two nearshore
stations, where it comprised 50 and 30 % (daynight average) of
the 9 and 22 m catch, respectively.
Raia binoculata (big skate),
was also abundant, composing 18 and 15 % of the catch at the 9 and
22 m stations.
Isopsetta isolepis (butter sole), ranked second or
third at 9 and 22 m.
Catch of Microgadus proximus (Pacific
tcincod), ranked first in abundance in the nighttime tow at 9 m,
but was less abundant in other tows.
(starry flounder) and Hydrolag
Platichthys stellatus
colliei (ratfish), were also
common in collections from the nearshore area.
Of the additional
species captured at the 22 m station, two flatfishes, C. stigmaeus
and P. vetulus, and the osmerid, A.
elongatus were common.
At the 73 m midshelf station, Citharichthys sordidus
(Pacific sanddab), ranked first in abundance, comprising 65 % of
the total catch.
Microstomus pacificus (Dover sole),
I.
isolepis,
Parophrys vetulus (English sole), Eopsetta jordani (petrale sole),
12
Table 2.
Summary of overall species composition and ranking of
the 10 most numerically abundant fishes captured
indicates
indicates presence,
during May 1979
(""
absence).
"-"
Table 2
Station
73 m
Species
day (1)
day (2)
Isop8ett.a isopelia
2
3
2
2
Raja binoculata
4
1
3
9
8
butter sole
big skate
ng
2
night
3
3
1
+
9
+
3
8
8
Microgadus proximus
-
I'settichthys melanostictus
1
2
1
1
4
9
9
6
8
6
2
7
Citharichthys sordidus
-
-
-
-
-
1
1
Hydrolagus colliei
8
5
5
4
5
-
10
Microtomus pacificus
-
-
-
-
4
2
-
-
-
-
-
5
4
-
-
-
-
6
6
-
+
+
+
7
5
Pacific tomcod
sand sole
Parophrys vetulus
English sole
Pacific sanddab
ratfish
Dover sole
Eopse t ta jordani
petrale sole
Glyptocephalus zachirue
-
Lepidop8etta bilineata
-
Citharichthys otigmaeus
-
-
4
3
-
3
6
7
7
8
-
+
Spirinchus starksi
5
+
9
5
+
-
+
Allosmerus elongatus
-
-
-
6
-
-
+
Ophiodon elonatus
-
-
+
-
-
9
-
rex sole
rock sole
speckled sanddab
Platiiohthys stellatus
starry flounder
night smelt
white bait smelt
()
lingcod
Pleuronichthys decurrens
curlfin sole
-
-
-
-
+
+
Table 2 cont'd.
Station
day ifi
llhlrPPTrO8OpOfl anale
6
73 m
22 m
gin
8
spotfin surtperch
10
!y_tI
+
night
!j&
+.
a k!ai d' I
sandpaper skate
4
kija ,hin,i
10
long nose skate
Ocella verrucosa
7
7
-
10
+
+
warty poacher
Scorpaenichthys ,nannoratus
cabezon
Ste henna xyoeterna
+
+
+
+
+
7
+
10
+
+
pricklebreast poacher
AnaPrhichthys ace ihatus
wolf-eel
-
10
Leptocottus an7r tus
+
staghorn culp1n
Merluccius productus
Pacific hake
9
Be! as tea mebanopa
black rockfish
!'ollaina barbata
tubenose
I0
-
-
+
+
-
+
-
-
+
-
-
-
poacher
Lyopsetta exiZs
slender sole
L)nbiotoca laterahis
striped surfperch
Hexaqramua deoagz'an,nua
kelp greenling
Knophrys bison
buffalo sculpin
Spirinchus thaleiohthys
night smelt
Lipanis pubchehlus
showy snailfish
+
+
-
-
+
+
II
15
and Glyptocephalus zachirus (rex sole), ranked second through
sixth, respectively.
Biomass
Estimates of total biomass are listed in Table 1 for May and
August tows.
of weight.
Figure 2 stmimarizes the species composition in terms
Total fish biomass ranged from 41
475 and 7
g/1O m2 among the tows for May and August, respectively.
57
Herding
by tow lines and bridles may cause an overestimate of biomass
(Main and Sangster, 1981).
Conversely, trawl avoidance by fish
would cause underestimation of biomass.
Sector scanning sonar
studies of otter trawl avoidance have shown the probability of
capture for Pleuronectes platessa, plaice, located between the
doors, to be about 0.5 (Harden Jones, 1974).
Therefore, the
biases caused by herding and avoidance may tend to offset each
other.
The large differences between May and August could be
attributed to the gear change between those two months, or to
displacement of fish by large concentrations of the medusae,
Chrysaora fusescens which were encountered at 9 and 22m during
August.
Raja binoculata dominated fish biomass at the 9 and 22 m
stations, composing an average of 33% of the biomass (Figure 2).
Psettichthys melanostictus and P. stellatus were also important by
weight at these stations (12
26% of biomass, respectively).
Isopsetta isolepis composed 34% of the 22 m station catch.
Citharichthys sordidus was dominant by weight as well as number at
the 73 m station, composing an average of 54% of the catch (range
16
9mSTATION
73m STATION
22m STATION
tJ
Iscpsettc
,So/eo,s
*
I
Rcjc
b,nocu/ctc
I
M,croqradus
prox/mus
Pserficnrnys
'
rne/onost,CtuS
Poroplrys
vetu/us
C
*
/
CrnoricM/'ys
I
sord,dus
41,croslomus
pacificus
jordofl
Glyptoceotlo/us
zocfl,,vs
LepI/240settc
41/'neolc
Ctflorrcht/iys
st/qmoeus
=75
*
Ii
C
0her
20
40
20
AVERAGE
Figure 2.
%
40
0
20
40
60
COMPOSITION OF CATCH
Average percent composition by weight of trawl catch at
three depths off Moolack Beach (hatched area = May, open
area = August, * = present at <2% of total of fish catch
of a tow).
17
31
71%).
The proportion of total catch contributed
individually by P.
Jordani
vetulus, 6. zachirus, M. pacificus, and E.
averaged only 6
7%.
Length Frequency
Length frequency distributions for fish species common in May
collections and those examined for stomach contents are shown in
Figures 3, 4 and 5 for each station.
Food Habits
The number of each species of fish examined, proportion of
empty stomachs, and stomach fullness are summarized by station in
Table 3 for the May cruise.
16.5% were empty.
Of the 714 fish stomachs examined,
The amount of food material that could not be
identified because of its advanced state of digestion ranged from
0
71.6% by weight of the total stomach contents for most fishes.
Two species had a relatively high proportion of unidentifiable
stomach contents:
and C.
H. colliei (9 m sta., 71.6%; 22 m sta., 54.0%)
sordidus (73 m sta., 47.4%).
This information is listed
at the bottom of each principal prey table and the bottom of each
summary table in the appendices.
Cumulative prey curves were constructed to investigate diet
diversity and whether a sufficient number of stomachs was examined
to identify the principal prey spectrum (Cailliet,
1977).
For
common predator species at each station, cumulative number of prey
is plotted against number of fish stomachs examined (taken
randomly) (Figure 6).
In general, curves for all predators were
P/otichThys ste/Ictus
i:
0
5
Psettic/ithys
rne/cnostictus
Hydrolaqus co/i/el
0I
Roja /nocu/ctc
night
:
Re/c binocu/oto day
2;
STANDARD LENGTH (mm)
Figure 3.
Frequency distribution of lengths for fishes collected at
the 9 m station during May 1979. Hatched area represents
the distribution of lengths for fishes used in stcinach
content analysis (the maximum number shown for each size
group represents the sum of fishes measured).
19
A //osmerus
elongotus
Sp/r'nc/nis
Cifhcrichlhys
40
s/C,ksl
s/iqmceus
Mlcroqoo'us
prOxrn7l/S
3J
I
V
I
"
0'
0
o,
P/atichrnys
/sopsetto
steiotuS
I$/4IS
Pcropflrys
Psetticflt/'ys
yeW/us
/flC/0fl05//CIU5
0
1
gin_rE
/
'
'p
t'
1.0'
P'
1.0'
Hjdro/ogus coil/el
: I
Rap b/noculo/o day
0
,49
45
.
P
1.'
0
,
P
'
c
STANDARD LENGTH (mm)
Figure 4.
Frequency distribution of lengths for fishes collected at
the 22 m station during May 1979. Hatched area represents
the distribution of lengths for fishes used in stcinach
content analysis (the maximum number shown for each size
group represents the sum of fishes measured).
Is onset/c
Op/'iodon
elon go/us
20
10
L
0
I0
Pcrophrys
ye/u/us
Ci/horichthys
j
sordidzis
/
0
Micros/ornus
Eopse/tc
jOrdQfli
11.1
20
G/yptocep/clus
zchirus
Lep/dopsetta
1
A
0
c
STANDARD LENGTH (mm)
Figure 5.
Frequency distribution of lengths for fishes collected at
the 73 m station during May 1979. Hatched area represents
the distribution of lengths for fishes used in stxiach
content analysis (the maximum number shown for each size
group represents the sum of fishes measured).
Table 3.
Summarization of the number of each fish species examined, proportion of
empty stomachs, and stomach fullness by station.
9m
examined
Empty
Rajubinoculata
13
0.0
Raja kino.aidii
(22)
0
%
N
0
Raja rhina
Hyh'olagu8 aolliei
(12)
-
0
b'pirinchuo at.arkoj
6
0.0
Nyperprosopon anale
Soorpueniohthys mmn'n,ozutus
(5)
(0.0)
53.9
(0.0)
-
-
-
-
-
-
(0.0) (83.3) (16.7)
AIioa,nerua elongates
22m
Stomach Fullness
1/3
213
3/3
0.0
46.1
(0.0) (22.7) (77.3)
-
Miarogadmms proximus
STATION
-
66.7
-
33.3
(7.4) (100.0)
3
0.0
100.0
(3)
0.0
0.0
0.0
0.0
0.0
ex
amlned
N
29
(35)
%
Empty
STATION
73in
Stomach Fullness
1/3
2/3
3/3
0.0
37.9
44.8
17.3
(11.4) (25.7) (42.9) (20.0)
Stomach Fullness
1/3
2/3 _f
3
0.0
0.0
t,6.1
33.3
-
-
2
0.0
0.0
50.0
50.0
0
-
-
-
-
4
0.0
0.0
1,0.0
50.0
0.0
0
-
-
-
-
0
-
-
-
-
-
-
-
0
-
-
-
-
-
33
60.6
24.3
9.1
6.0
0.0
50
34.0
28.0
12.0
26.0
0.0
STATION
-
87.4
(66.7) (33.3)
amined
%
Empty
-
0.0
(0.0)
ex-
0
16
(0.0)
N
19
21,0
12.6
47,4
15,8
15,8
0
0
-
-
0
-
-
-
-
1
0.0
0.0
100.0
0.0
0
-
-
-
-
40.0
40.0
10.0
0
-
Stellerinuxyosterna
2
0.0
100.0
5
0.0
Ophiodon elongates
0
-
-
-
-
0
-
-
-
-
5
20.0
20.0
0.0
60.0
Cithuriohthya sordi4ua
0
-
-
-
-
0
-
-
-
-
51
23.5
33.3
47.1
15.7
Cztharm.chthys stgmv.wua
0
-
-
-
-
33
6.1
3.0
Eopaetta jardani
0
-
-
-
-
0
-
-
0
-
-
-
-
0
-
-
Glyptocephaius
aaohirua
laopaett.a isolepia
13
23.0
Lepidopsetta bilineata
0
-
Miapostomu, j,aaiJicus
0
-
Pu'ophrys vetulua
0
-
Plmtihthys stellatua
Pleuronohthya decurrena
Psettichthymm melanom,ti,tua
TOTAL
20
0
39
138
60.0
-
25.6
38.5
-
-
0.0
-
38.5
38.5
0.0
33
30.3
27.3
51.5
-
33.3
39.4
0
-
-
-
-
-
-
-
-
-
33
12.1
21.2
39.4
27.3
-
37
0.0
10.8
43.2
46.0
9.1
32
9.1
31.3
31.3
28.0
-
-
0
-
-
-
-
29
6.9
17.2
44.8
31.0
-
-
0
-
-
-
-
27
11.1
25.9
51.9
11.1
-
-
16
(5)
6.3
6.3
35
2.9
14.3
74.3
3.6
(0.0)
(0.0)
20.0
14
28.6
42.9
20.0
-
15.4
-
20.5
0
30
313
-
36.7
-
16.7
0.0
87.5
(20.0) (80.0)
21.4
7.1
-
20.0
-
26.6
0
-
-
-
5
0.0
0.0
0.0
0
-
-
-
263
-
100.0
-
72
[:17:1
50
40
30
.
20-i
x
,Pstel
l0
>
uJ
Ls::ISiIs9
P mel.
0
0
22m.
22m.
20
P
M prox
C. Sn g
eta
elan
':
z
LiJ
73m.
60
73
vet
I-
50
J
zac
/0
40
(-)
30
C ear
pa c
E or
01
0
0
20
30
40
NUMBER
Figure 6.
0
0
20
30
40
OF FISH
Cumulative number of prey taxa as a function of number of
stomach samples analyzed for each fish species (A. elon. =
A. elongatus, C. sor. = C. sordidus, C. stig. =
stigmaeus, E. jor. =
jordani, G. zac. =
zachirus, H. col. = H. colliei I. iso. =
I. isolepis, L. bi. = L. bilineata, M. prox. =
It!.
proximus, M. pac. = M. pacificus, P. vet. =
P. vetulus, P. mel. = P. melanostictus, R. bi. =
K. binoculata, S. star. = Spirinchus starksi).
.
.
.
23
asymptotic, with the exception of
.
isolepis and P.
stellatus at
the 9 m station, and G. zachirus and L. bilineata at the 73 m
station, indicating that in most cases the number of stomachs
examined was adequate to include the principal prey.
Shape and height of cumulative prey curves may yield some
information on feeding habits.
A steep curve rising to a high
asymptote implies a great diversity in individual diets.
case of P. vetulus, 50
8
12 stomachs.
In the
60 unique prey were encountered from only
A curve gradually increasing to a high asymptote
implies a broad diet with lower diversity in individual stomachs
(suggesting greater selectivity) (eg. G. zachirus and L.
bilineata).
In contrast, R. binoculata, P.
melanostictus,
Citharichthys stigmaeus (speckled sanddab), Allosmerus elongatus
(whitebait smelt), and Spirinchus starksi (night smelt) reached a
low asymptote (< 10 prey) after 5
diet diversity.
10 stomachs, indicating a low
The remaining species were intermediate,
requiring about 20 stomachs to reach an asymptote.
In the following three sections, food habits data will be
presented for fish species collected at each station.
The results
will begin with a generalized station by station description of
major prey types followed by specific details for major prey
species.
9 rn Station
The average percent composition of major prey taxa in the
diets of fishes collected at the 9 m station are presented in
Table 4.
Two general feeding types can be recognized:
pelagic
and/or epifaunal feeders, and epifaunal and/or infaunal feeders.
Table 4.
Average percent composition by weight of major prey taxa (weights of lower taxa
summed) in the diets of fishes collected at the 9 m station off Moolack Beach,
Oregon, May 1979 ("0" = number of stomachs examined).
0
4
/;..
.1
0
day
I0I.Y('IlAlTA
28.7
0.2
0.1
PII.ECYI'()1)A SIPhON
0.0
0.0
45.2
0.0
0.1
0.0
MYSl0Al1A
0.1)
<0.1
1.5
AMlhIIh'OI)A
14.4
24.6
0.0
IWLAl'ODA
27.4
97.5
0.0
0.0
0.7
0.0
0.0
22.7
24.0
6.2
5.5
0.2
0.0
0.9
0.0
M01,1.LISCA
i<EAI'0DA I.AIIVAE
O'1E1cF1T11YLE
0.0
0.0
0.0
0.0
.çP
'
<
.
.'< '1'
night
10.8
<0.1
0.0
2.7
0.0
0.1
0.0
0.5
0.5
98.1
87.7
0.0
0.0
0.7
0.0
3.2
0.0
0.0
0.0
48.3
7.4
0.0
40.4
0.0
77.6
2.2
7.1
2.2
58.3
11.8
24.8
2.7
0.0
0.0
0.0
0.0
1.1
0.1
17.5
0.0
0.0
0.0
1.9
10.1
29.2
30.6
16.9
0.0
0.0
0.0
0.0
0.0
0.0
(1.0
0.0
0.0
25
Psettichthys melanostictus, M. proximus and S. starksi fed mainly
on pelagic mysids representing over 40% of the diet; decapods and
Epifaunal and for infaunal feeders
fishes were also important.
included R. binoculata, H. colliei, Scorpaenichthys marmoratus
(cabezon),
.
isolepis and
stellatus.
.
This second group of
fishes preyed upon a broad spectrum of epifauna and infauna
including polychaetes, molluscs, amphipods, decapods, Dendraster
excentricus (sanddollar) and fishes.
More detailed information on species composition of principal
prey (FO > 15%) in diets of fishes are summarized by feeding type
of the predator (e.g. pelagic and/or epifaunal) in Tables 5 and 6.
The group of pelagic feeding fishes fed on five mysid
species, but one, Neomysis kadiakensis, was most important (Table
5).
Additional common prey of M. proximus were surface tube
Crab zoea were
dwelling amphipods and small Crangon (< 40mm).
common in the stomachs of
starksi.
.
A detailed description of
the diet of P. melanostictus will be presented in a section on
size related changes in diet.
Stomachs of a few smaller fishes, less common in commercial
trawl catches, were examined:
the agonid, Ocella verrucosa, and
embiotocid, Hyperprosopon anale both had mysids, particularly
Neomysis kadiakensis, as a major dietary component (50
Raja binoculata and
.
100%).
colliei fed largely on Crangon
stylirotris, a sand shrimp (20
50 mm TL) and Cancer magister,
Dungeness crab (20 - 50 mm) (Table 6).
Crangon stylirostris
occurred in > 95% of R. binoculata stomachs.
One fish, Ammodytes
hexapterus (sand lance) was a common prey of R. binoculata (FO =
Table 5.
Percent frequency of occurrence (FO), and average percent composition by weight
(W) and numbers (1/) of principal prey for pelagic and/or epifaunal feeding
fishes collected at the 9 m station (May 1979).
1. tijh thy
melanost ictus
sand sole
SF0
SW
%#
Polychaeta
Micioadi
pPosunus
Spirinchiw
tcirksi
Pacific tomcod
SF0
SW
St
night smelt
SF0
SW
St
20.0
20.0
25.0
20.0
3.2
-
20.0
7.4
1.4
60.0
40.0
60.0
20.0
13.8
20.8
2.9
7.9
2.5
8.6
10.3
Gastropoda
Olit',ZIa sp.
Mysidacea
Mysidae
Aintho,rsi1<js iwisi
Aa?zOimy$ i<
lpt
A:Ikhornyait; ji'nitkii
N<ony3i8 kadikcn<ie
eyis rayii
35.5
19.4
38.7
11.8
1.7
7.8
2.5
6.8
58.1
16.1
24.3
25.4
2.7
2.5
20.0
13.3
2.9
40.0
20.0
37.6
20.0
25.0
20.0
<0.1
<0.1
20.0
2.2
2.0
2.8
2.4
1.2
1.4
4.4
20.0
20.0
40.0
40.0
20.0
0.7
2.9
40.0
19.3
13.0
20.0
2.7
10.0
20.0
17.8
18.0
0.0
0.0
12.5
2.9
Amphipoda
Gaimtiaridea
Anqeliea inactocephal
4tyln< t:d<ns
:;ynhe1 diem <hoe,rukeri
16.1
2.2
MUHdZbU lophoxus
,nL(flrO8tr2tU8
8.6
11 .1
Decapoda
Canjon styliruatria
19.4
9.3
7.4
Brachyura
Brachyura unegalops
Ccneep nk1jister
22.6
1.1
5.8
Porcellanidae zoea
Porcellanidae megalops
Osteichthyes
Mi.zogadus proximus
Other
35.5
31.6
23.3
7.5
9.4
20.0
5.5
10.0
20.0
0.1
2.9
20.0
16.9
3.2
0.0
0.0
F'.)
Unidentified material
12.3
13.7
0.0
0"
Table 6.
Percent frequency of occurrence (FO), and average percent composition by weight
(W) and numbers (#) of principal prey for epifaunal and/or infaunal feeding
fishes collected at the 9 in station (May 1979).
Polychaeta
Nothijo ixide,cena
1501)Set ta
P1atiCht1ly3
S(5DMiChthyi3
iso1p
bteliatU
inairncc4tu..,
butter sole
starry flounder
SF0
SW
%ä
SF0
20.0
6.0
-
30.0
22.7
SW
%#
cabezon
SF0
SW
Sä
33.0
3.0
Raja binucula ta
day
SF0
SW
bi g skate
%
SF0
!Iydrotaju
collict
ratfish
night
SW
St
SF0
SW
St
23.1
10.8
5.1
15.4
0.1
2.1
23.1
0.4 11.2
20.9
Gastropoda
Nwsariu, Jossatus
0.1
Pelecypoda
44.4
Siliqua patula siphon
45.2
35.8
Mysidacea
Aoantho,njis daviai
33.3
Neornysis rayii
1.5
7.0
Miphi poda
Atylus triden8
20.0
7.9
12.4
33.3
24.3
32.8
FRppornedon dent2,culatus
Decapoda
Cviu)on atylixoatris
30.0
26.4
18.8
brachyura
Caur ,miitp
20.0
1.0
0.1
Majidae
66.7
33.9
13.0
33.3
1.0
3.5
100.0
33.3
61.1
1.5
67.8
1.8
100.0
96.5
92.9
95.5
73.9
76.4
61.5
10.2 25.4
59.1
13.8
10.6
61.5
48.1 30.3
Ech noderina ta
i
L.,nIrjt.a, exntriaus
22.2
22.7
14.8
NJ
-3
Table 6 cont'd.
Iaopetta
Osteichthyes
cz'pnihthja
iaoiepia
8telkltu
butter sole
starry flounder cabezon
SF0
SW
St SF0
SW
510
SW
30.0
2.8
St
Raja binoaulczta
mnrnørqtus
bi
6.2
SF0
46.2
SW
1.3
St
45.5
33.3
Citharichthya atignueus
Other
Unidentified material
SF0
33.2
5.5
41.6
7.8
2.3
16.6
0.9
3.9
0.0
0.0
23.4
2.2
8.7
SW
ratfish
St
SF0
SW
St
30.8
23.1
2.3
21.8
8.1
6.1
2.9
Ajr,widytea hexapterue
AOnflldae
colhe.
night
day
St
!Iydrolagwi
sk8te
4.2
8.2
4.1
9.0
8.6
4.4
6.3 11.7
71.6
46%, Table 5).
Isopsetta isoletds consumed polychaetes, gammarid
amphipods and Crangon stylirostris where as P. stellatus fed
mainly on siphons of large Siligua patula (razor clams), small
Dendraster excentricus (sanddollars) (2
25 mm test diameter),
and amphipods of the species Ampelisca agassizi and Atylus
tridens.
In a small sample of three S. marmoratus, Cancer
magister were observed to be a major prey
(61%) (Table 6).
22 m Station
Psettichthys melanostictus, C. stigmaeus, M. proximus, S.
starksi, and A. elongatus fed primarily on pelagic and/or
epibenthic crustacea.
As in the case of the 9 m station, pelagic
mysids were the major prey, representing over 50% of the diet by
weight and number (Table 7).
Neomysis kadiakensis comprised over
70 and 85% of P. melanostictus and C. stigmaeus diets (Table 8).
In contrast, M. proximus fed on three different mysids in more
even proportions (Table 7).
settled I. isolepis (19
Two
.
stigmaeus had eaten recently
20 mm) (Appendix III).
Raja binoculata and H. colliei were two common epifaunal
predators at 22 m. They fed on Crangon stylirostris (20
and on Cancer magister sp. (20
50 mm) (Table 9).
50 mm)
In addition to
Ammodytes hexapterus (a common prey of Raja at 9 m), the flatfish,
C.
stigmaeus was also important.
When C. stigmaeus occurred in
skate stomachs, it was common to find 10
in size from 30
20 individuals ranging
50 mm.
Three flatfishes were characterized by epibenthic and/or
infaunal feeding at the 22 m station (Table 7).
Parophrys had a
diverse diet, feeding primarily on infaunal polychaetes,
Table 7.
Average percent composition by weight of major prey taxa (weights of lower taxa
summed) in the diets of fishes collected at the 22 m station off Moolack Beach,
Oregon, May 1919 ("0" = number of stomachs examined).
b
Q
')
Ql:
43
z,
'
day
23.8
7.6
11.3
20.9
0.7
0.7
W)I,ILJSCA
5.0
10.1
0.3
P13 .E( Y l'()I)A S I PIION
1.9
3.7
0.0
23.8
11.1
12.9
(IJMA( 'EA
9.5
2.2
0.3
I SUPUIIA
0.1
0.8
0.0
0.0
0.0
0.2
0.0
0.0
0.0
0.1
MIS I l)A('lA
1.9
2.9
0.1
0.1
I ON )I( ASIE II
8.4
18.7
44.7
l)l.(AI'OI)A
1.7
21.4
I0:(AIUI)A l.ALIVAE
ObTL ICIITIIY 1S
0.3
0.0
(YFII 1:11
1.?
II
)l,Y( Ii AEI'A
NE ME RI INEA
AMPII I P0l)A
$
ni yht
0.0
0.0
4.1
1.0
25.3
12.5
0.0
0.0
0.9
0.2
0.0
5.0
0.0
8.4
76.8
73.2
47.3
9.6
6.3
32.2
0.0
0.0
0.0
22.7
4.8
0.0
0.0
1.5
1.4
0.0
0.0
0.0
0.3
0.4
0.0
0.0
0.0
0.0
0.9
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.5
72.4
0.0
0.0
0.0
0.0
19.6
13.2
0.0
0.0
0.0
0.0
1.1
0.1
0.0
0.0
0.0
0.0
0.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
86.8
5(1.6
50.0
84.5
0.0
0.0
0.0
0.0
0.1
18.1
(1.0
(1(7
0.1
3.1
10(1
23.8
11.8
27.5
1.8
4.4
16.7
:1.2
0.0
0.0
1.2
0.0
15.5
0.0
(1,0
0
Table 8.
Percent frequency of occurrence (FO), and average percent composition by weight
(W) and numbers (//) of principal prey for pelagic and/or epifaunal feeding
fishes collected at the 22 m station (May 1979).
PB t tt(th thy8
melc4nostictua
sand sole
SF0
SW
SI
Ci thai'ichlhya
atijmcieus
Micro yadus
proxsmus
Al los,ntius
Spiiinqhus
tarksi
elon.qatus
Pacific tc'mcod whitebait snielt night smelt
50510 SW 50 SF0 SW SI SF0 SW SI
speckled sanddab
SF0
SW
Nysidacea
Mysldae
Acant1iiqsia
.4cinth.e!ia
Nconyaie kiliiknaie
?&o.,yoin
66.1
Lwii
40.0
85.0
1(1.1
/3.5
100.0
85.8
13.3
33.3
26.1
22.3
5.8
42.5
6.3
49
5.0
12.3
10.1
50.0
50.0
50.0
zyii
26.5
10.4
14.6
/3.5
62.9
8.5
59.1
18.2
17.3
20.1
9.0
Decapoda
(vinqo,I etyiiIoatkia
41.9
BracIyura megalops
Porcellanidae zoea
Paguridae megalops
30.0
22.4
17.4
Other
1.5
9.1
Unidentified material
1.6
Osteichth3les
3.0
11.2
18.2
20.0
18.1
14.4
20.0
2.2
1.5
19.2
7.5
33.0
18.2
21.0
16.1
8.8
9.4
16./
16.7
16.1
24.5
23.9
0.0
6.0
Table 9.
Percent frequency of occurrence (FO), and average percent composition by weight
(W) and numbers (#) of principal prey for epifaunal and/or infaunal feeding
fishes collected at the 22 m station (May 1979).
lcpa.t t
P(wophra
English sole
110 SW
SI
Polychaeta
Cha.tozon, ,.toaa
Glyinda as,niwru
Glyainde piata
it'na eaculdta
N.phtya sp.
Nreia ap.
OrbIniIdae
Anitid.a sp.
Et.one bp.
flalu,w.,aa spino&l
Spijh.uwa bombyx
60.0
0.8
-
60.0
20.0
46.7
60.0
66.7
20.0
46.7
20.0
40.0
75.3
93.3
0.1
0.3
3.7
0.3
3.0
17
0.1
'0.1
11.7
3.2
3.2
0.2
0.8
0.5
0.6
1.8
12.3
53.0
0.1
0.8
46.7
3.5
0.5
26.1
1.1
0.3
0.5
0.1
0.1
0.1
5.9
butter sole
SF0
SW
&i.Ja binoiu lz tci
t ih thyt
.Jtellutu8
starry flounder
P1
JoZ)i.Li
II
SF0
SW
Ia
20.0
0.1
0.1
20.0
0.1
1.4
20.0
0.2
2.0
20.0
0.1
0.4
Jay
SF0
SW
bl 9 5k ate
XI
SF0
night
SW
Hydzo lujiw
ratfish
11510
SW
It
Gas tropoda
OjjpoLLi sp.
Pelecypoda
Pelecypoda sIphon
SiIiqiJ patul4
TellInIdae
26.0
25.3
6.4
26.7
1.4
9.4
18.8
0.9
2.1
Hysldacea
Mysldae
Aohaonyui
zbnitakii
46.7
53.3
0.4
1.4
0.4
1.7
N..c.nVaia Icadjak.en,ja
Cianacea
Anüiiocotorus
Oistgjlia ep.
Dist1opa&a Juijooni
1ioiilaripiopa
ap.
93.0
26.7
80.0
60.0
4.6
8.4
2.0
2.3
6.4
0.3
6.6
3.3
20.0
2.0
2.6
15.0
0.5
4.2
16.0
0.2
2.2
16.7
44.9
20.0
0.1
0.7
3.6
6.4
8.8
1.3
Isopoda
J/Hi,iut.a biouupida
tJ
Table 9 cont'd.
vetuiva
English sole
SF0
SW
SI
iaoiepi.a
butter sole
SF0
SM
Raja binoculata
Piatichthya
Iaopaetta
Parophrya
atellatua
starry flounder
SI 510 SW SI 510
day
SW
bi
SI
skate
SF0
Iiydrclagua
ooflz.ei.
ratfish
night
SW
SI
SW
SI
20.0
1.0
3.4
66.1
25.6
36.2
SF0
Aiiiphlpoda
36.0
GaRmlarldea
An5,oli,a ajaaaiai
.4qeliaea niarocBphata
&,llauatoriud ae,ajllu
konou1odee apinipe8
Sy.wheiidiwi
l'hotia
Photia
aFio.ni&ri
p.
breulpea
Phoxocephafldae
Foxiphalua l,tu3ideflS
kindibulophoxua
UflijQt8tfl4tUd
khepoxyniwa epzatomua
Rhepuxyniva ui9itthJu
1.2
3.0
8.8
2.4
1.5
10.5
10.0
3.7
33.3
20.0
47.1
80.0
0.1
0.1
0.2
0.5
0.2
1.2
6.9
3.1
80.0
80.0
80.0
0.2
0.2
0.6
1.7
1.4
2.4
20.0
33.3
0.6
1.0
0.4
0.5
33.3
20.0
0.1
0.5
'0.1
0.1
46.7
0.1
0.6
66.7
93.3
93.3
86.7
7.0
8.1
0.9
3.0
15.0
2.5
1.8
20.0
17.0
11.5
30.0
12.4
11.4
20.0
0.1
1.4
20.0
20.0
20.0
20.0
60.0
30.0
30.0
1.3
0.1
2.1
14.3
9.3
6.4
0.4
5.4
1.6
2.6
21.4
21.0
2.7
40.0
44.1
22.6
20.0
0.7
Oecapoda
CaunJon atylix.oatria
Cwuevnegioter
Ptnnotherldae
Plniiother$dae bee
Plnnotheridae meyaiops
Porcellenldae zoea
Porcelianldae megalops
20.0
9.4
12.9
Pagutidae megaiops
1.1
15.9
62.1
43.1
32.1
46.3
14.2
11.2
1.0
2.6
21.6
44.8
3.9
17.3
7.4
22.3
3.6
9.8
/2.4
44.0
62.0
29.1
34.5
18.8
23.3
30.0
2.1
11.7
2.4
13.6
8.8
15.5
Echinodermata
L)enfrataz
exoentriaua
80.0
8.4
3.6
46.0
18.7
14.9
1.5
30.0
4.8
4.3
Ophluroldea
80.0
1.1
Heaiertea
93.3
20.9
-
-
-
Osteichthyes
odyta
hex pterua
Citharichthpa ati0ewua
Other
UnidentifIed materIal
5.9
19.9
6.5
37.0
4.2
28.5
0.1
ii
4.3
14.7
9.6
45.9 42.6
54.0
amphipods, nemerteans, and cumaceans (Table 9).
Frequency of
occurrence was high (< 60%) for most principal prey, indicating
that each stomach contained many prey taxa (average across all
prey taza = 22 taxa/stoinach).
The polychaete, Si,ioihanes bombyx
and amphipods, Ampelisca and Eohaustorius were particularly
important by weight.
Isopsetta isolepis had a diet similar to P.
vetulus, but included more epifaunal prey (Crangon and Cancer),
and fewer infaunal polychaetes and amphipods.
Platichthys
stellatus fed on decapod larvae and small sanddollars (Dendraster
excentricus) which were found intact along the length of its
tubular gut.
Bivalve siphons (Siligua patula), an important food
of P. stellatus at 9 m, were not observed in stomachs of fish
collected at 22 in.
However,
large Siligua appeared to inhabit
the 22 m station area, because whole individuals were commonly
observed in stomachs of H.
colliei (Table 9).
73 m Station
Diets for the midshelf (73 in) fishes are summarized by major
prey taxa in Table 10. Two flatfishes, E.
fed both on and above the substrate.
jordani and C. sordidus
Citharichthys sordidus had
the most pelagic food habits of any fish collected at the 73
station.
in
Its prey included: the pelagic mysid, Caesaromysis
vanclevei, the pteropod Limacina, copepods, hyperiid amphipods,
the euphausiid Thysanoessa spinifera, salps, and chaetognaths
(Table 11) .
In addition,
flatfish,
isolepis.
I.
.
sordidus consumed a recently settled
Principal prey of E. jordani included
juvenile pleuronectiform fishes, Crangon alaskensis, and the
mysid, Acanthomysis sculpta (Table 10 and 11).
A more detailed
Table 10.
Average percent composition by weight of major prey taxa (weights of lower taxa
summed) in the diets of fishes collected at the 73 m station off Moolack Beach,
Oregon, May 1979 ("0" = number of stinachs examined).
J
F,,
-'
,J'
I
.
\?J
'4fr
.'
'4
I'Ol,YCIIAI!lA
86.2
20.4
21.3
7.5
17.0
100.0
0.0
'0.1
0.0
0.0
0.0
1)ASTh0I'ODA
6.4
7.0
2.1
1.3
0.0
0.0
'0.1
0.2
0.1
0.0
0.0
PEI.ECYI'01)A
2.0
1.6
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
(iAIIIIAIIOII)EA
15.2
26.5
36.0
9.3
19.1
0.0
0.0
1.9
0.0
0.0
0.0
0.0
CUMACEA
10.0
1.7
1.5
3.9
2.0
0.0
0.0
1.5
0.0
0.0
Ii01'00A
'0.1
8.9
6.7
1.4
7.6
0.0
0.0
'0.1
0.0
0.0
0 0
1.0
0.0
0.3
1.1
0.0
0.0
10.4
14.7
0.0
0.0
0.0
0.0
0.0
0.0
0.0
UY8I1)ACA
ECIIINOIIEIII4ATA
2.2
0.4
0
1
0.0
2.2
0.0
0.0
A3CII)KACEA
0.3
0.0
0.6
0.0
14.4
0.0
0.0
0.0
0.0
0.0
0.0
clay PEI.l.E'3
2.4
24.5
1.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
I'II310I01)A
0.0
0.0
0.0
0.0
0.0
0.0
0.0
10.44
0.0
0.0
0.0
C01EI'0I)A
0.3
0.4
1.2
0.0
0.1
0.0
0.0
7.4
0.0
0.0
0.0
IlYPI11IJEA
0.0
0.0
0.0
0.0
0.0
0.0
0.0
3.9
0.0
0.0
0.0
ELJPHAIJSIACEA
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1(1.2
(1.0
0.0
0.0
0ECAI00A
2.8
5.8
25.4
46.8
31.0
0.0
111.6
58
25.6
2.2
0.0
0.0
Al.I'A
CI4AEi0t,NAlIIA
OSTEIC(1T(1(ES
(1441134
0.0
0.0
0.0
0.0
0.0
0.0
0.0
9,3
0.0
0.0
0.0
0.0
01)
0.0
0.0
0.0
0.0
5.0
0.0
0.0
0.0
0.0
0.0
2.1)
3.7
0.0
'14.3
19.6
14.3
97.8
400.0
44.0
0.0
0.0
UI)
2.2
5.9
I
.1)
(.9
2.9
0.0
1.7
('3
Ui
Table 11.
Percent frequency of occurrence (FO), and average percent composition by weight
(W) and numbers (#) of principal prey for pelagic and/or epifaunal feeding
fishes collected at the 73 m station (May 1979).
Ci than
ch thy2
ordidus
1'ops t ta
jordani
petrale sole
SF0 SW
S
Pacific sanddab
SF0
SW
St
kaja
Raja
binocu iota
big skate
SF0
SW
St
33.3
26.7
Oplu udon
kaja
rhino
k in cajd ii
elonga tuu
sandpaper skate
longnose skate
SF0
SW
St SF0 SW St
llngcod
SF0
SW
St
75.0
15.0
75.0
Polychaeta
Gas tropoda
L,injaain
sp.
38.5
10.8
12.2
lwnchpua
38. 5
6.7
18.8
25.6
15.4
13.8
0.9
9.5
3.6
15.4
2.1
3.6
20.5
16.2
12.3
0.1
Copepoda
a 1,nua
'
Mysidacea
(lParny53 t)u,wlevei
4wtharnyai; ne1hro;hraialrna 51.7
10.4
29.8
100.0
0.3
11.5
7.7 100.0
19.8
25.8
7.8
39.6
15.6
3.1
3.1
Aitiph lpooa
Ilyperidea
Euphus1 iacea
1J,ynocau tqinifera
Decapoda
(ran;on sp.
alaBkn8i8
(
33.3
51.7
14.7
Za1JOfl a 1 ha
100.0
50.0
50.0
I/ it,is
aIIfl
Pa9ur idae
ii a c hyu ra
(.i'i, ,,szjis taz
P nnotheridae
20.5
9.2
3.7
Chaetounatha
20.5
5.0
5.9
,a
Agonidae
17.2
jirnbia
33.3
3.2
7.7
33.3
33.3
0.2
2.6
21.6
12.8
50.0
Salpa
Osteichthyes
0.7
15.3
5.8
7.8
33.3
35.4
33.3
33.3
33.3
35.7
2.2
2.6
2.8
7.8
4.7
50.0
1.7
18.0
25.0
0.4
1.3
25.0
<0.1
1.3
75.0
46.3
41.6
4.2
(a
m
Table 11 cont'd.
FJopsetta
jordani
petrale sole
SF0 SW
SI
P1 euroneti formes
20.7
12.7
17.2
10.5
20.7
17.3
13.2
12.9
6.8
6.3
Other
13.1
16.0
Unidentified material
10.8
lh.ar nordilun
SF0
SW
SI
7.8
24.1
Ci O:ii
Citharichthys
sordidus
Pacific sanddab
Glyj toc(qha lam machiram
laopmetta isolepia
Micron tof,rus pacificum
16.0
8.9
3.8
26.4
26.6
47.4
Raja
binoculata
big skate
SF0
SW
SI
33.3
33.3
2.2
2.2
0.1
0.2
0.0
7.8
0.0
Raja
Raja
Ophiodon
kincaidii
rhina
elongatus
sandpaper skate
longnose skate. llngcod
SF0
SW
SI SF0 SW SI SF0 SW
100.0
33.8
0.0
20.6
22.9
0.0
50.0
25.0
25.0
25.0
1.2
4.2
25.4
20.8
19.7
0.0
0.0
9.5
9.7
25.0
25.0
4.2
SI
20.8
10.7
14.3
0.0
0.0
6.3
1.3
0.0
-4
38
description of the diet of E.
iordani appears in the section
entitled: "Sizerelated Trends".
A few individuals of three skate species were captured at the
73 m station.
Small Raja kincaidii, sandpaper skate, preyed on
crangonid shrimp and juvenile C. sordidus (Table 11).
Fish
comprised the majority of the diet of two larger skates, Raja
rhina, longnose skate, and R. binoculata.
sordidus, G. zachirus and I.
isolepis.
Raja rhina fed on C.
One large
binoculata
.
(1300 mm) had eaten a 450 mm Anoplopoma fimbria (sablefish), plus
two large pleuronectiforms.
Ophiodon elongatus, iingcod, fed exclusively on fishes.
With
the exception of C. sordidus, most Ophiodon prey were in an
advanced state of digestion, and therefore, unidentifiable (Table
11).
Six species of flatfishes at this station had fed on both
epifauna and infauna (Table 10).
Four of them, Parophrys vetulus,
M. pacificus, G. zachirus and I. isolepis, fed in varying degrees
primarily on inlaunal polychaetes and amphipods.
A small sample
size of stomachs from a fifth, Pleuronichthys decurrens (curlfin
sole), contained just the onuphiid polychaete, Nothria irridescens
(Table 12).
clear.
Dietary differences among these four species are
Polychaetes were more important in the diet of P. vetulus
on a weight basis than in the diets of the other three
pleuronectids (56% vs. 17
21%), and P. vetulus fed on a more
diverse assemblage of polychaetes
(28 taxa vs. 7
14).
Cumaceans were also more common in the diet of P. vetulus than in
those of the other fishes.
Prolate spheroid and spheroid clay
Percent frequency of occurrence (FO), and average percent composition by weight
(W) and numbers (/1) of principal prey for epifaunal and/or infaunal feeding
fishes collected at the 73 m station (May 1979).
Table 12.
Microstomw
Pai'ohrg
vetuZu
English sole
Dover sole
9109W
91
910
SW
-
37.5
15.6
71.4
25.1
Capitellidae
17.1
2.7
1.8
Chaetopteridae
40.0
20.0
1.6
1.0
51. 1
2. 1
6.1
1.8
7.9
Polychaeta
Spiu.:etopt'.ew cotaeu,n
(Jkw town s tosc
GlL wmijera
Ma1dnidae
Nqty2 sp.
31.4
31.4
45.7
1.6
0.5
2.3
1.4
1.2
6.5
17.1
12.5
1.9
G1yptocepha1u
Lepidopsetta
rex sole
SF0
SW
rock sole
SF0
9W
zachirus
pacifiou
SI
-
35.1
18.9
6.4
2.1
SI
-
Ibopetta
bilineata
21.9
2.5
Pleuronichthys
decurrena
iaolepi8
SI
-
butter sole
SW
SI
SF0
13.8
4.6
-
11.2
3.4
5.5
Terebellidae
iit1
20.8
25.7
2.0
0.8
4.5
1.5
sp.
18.5
3.0
3.0
48.2
1.1
9.5
25.9
0.2
4.4
G2 s tropoda
C5,lichna sp.
Olioeila
51.4
4.8
4.2
16.7
sp.
6.3
3.6
24.3
2.0
2.3
35.1
1.2
6.4
Pel ecypoda
Copepoda
AetediwB pacificu
17.3
0.3
1.6
Mysidacea
Aeanthomysia nephrophChalrna
Cuijiacea
IIcmila'npvupa sp.
.
17.1
0.2
1.1
51.4
8.4
12.6
29.2
1.7
5.7
18.9
0.4
3.6
33.4
5.5
8.3
29.7
6.4
3.9
5.5
27.0
0.9
3.5
18.5
0.2
16.2
81.1
Li
13.1
1.2
15.7
66.1
8.1
Isopoda
:;/i1,t1 ep.
17.2
7.0
4.1
2.2
20.1
1.9
8.1
16.2
31.0
8.9
11.8
Aisphi poda
Gai,inaridea
aJ,auiui
A,relia na'o,e1ha1a
17.1
0.6
1.1
17.1
0.4
4.8
0.9
8.0
62.9
29.2
1.9
910
SW
50.0
2.1
100.0
97.9
SI
1.6
[Wit h,, a j ii desc,ens
T,','iijia jiya
.lnaitida, sp.
curlfin sole
100.0
Table 12 cont'd.
Parophry8
ye tu lus
English sole
SF0
SW
SI
40.0
0./
2.4
Mioroatomus
pacificue
SW
SI
Rhachtropis inflat.
Rohau.9torj
sp.
I.ysianassidae
llip.m.ion sp.
Ihoti8 sp
Re1oxyniwi
p.
Rhepcxyniva
epiatofm4z
28.6
31.4
L/
6.1
2.0
17.1
0.3
2.2
0.9
70.8
19.6
Lepidopsetta
Iaopaetta
zachi rue
hi iinea ta
1.80 iepis
rex sole
Dover sole
SF0
Glyptocephalus
39.5
Pieuronichthya
decurrene
butter sole
rock sole
SF0
SW
SI
SF0
SW
SI
21.6
0.6
2.0
22.2
0.3
1.8
29.1
48.7
2.2
7.2
5.2
7.8
21.6
0.4
35.1
4.0
40.5
1.7
2.5
5.3
4.6
46.1
4.0
5.9
SF0
SW
SI
17.2
2.2
6.0
24.1
14.3
3.6
31.0
12.2
9.9
20.1
2.2
5.0
31.0
14.4
16.5
28.9
29.5
curifin sole
SF0
SW
SI
Decapoda
Crunqon sp.
48.0
11.4
9.1
Paguridae
Pinnotheridae
17.1
2.2
2.0
Ophiuroidea
45.7
1.6
2.6
17.1
2.4
40.5
12.1
6.6
Ascideacea
Spheroid pellets
Ellipsoid pell.ts
54.2
21.6
20.8
2.9
Osteichthyes
Pleuronectlfonnes
25.9
4.2
3.5
(.itho.richthye aordidua
31.0
59.3
24.2
24.8
10.7
18.9
20.0
20.7
I8og8ett
i&1epi
Other
16.9
Unidentified material
23.3
19.0
24.1
10.8
32.9
33.6
21.7
21.9
3.3
3.7
0.0
0.0
0.0
0
41
particles (1
1.5 mm diam.) were common in the stcinachs of M.
The origin of these particles could
pacificus (24.5% by weight).
not be ascertained, 'but they are probably benthic invertebrate
feces or pseudofeces.
also uncertain.
The nutritional value of these particles is
Of the ten amphipod taxa consumed by Microstomus,
the genus Photis was most important with greater than 70% FO.
Ainphipods and pinnotherid crabs were dominant prey of G.
zachirus.
The diet of I isolepis was distinguished by the
presence of an unidentified, sediment dwelling ascidian, and two
decapods: Crangon and pagurid crabs.
The remaining pleuronectid, Lepidopsetta bilineata, had a
diet distinct from the above five species.
The major prey of
Lepidopsetta were recently settled pleuronectiform fishes (53%),
including ç. sordidus (30
that
40 mm) and j. isolepis (20
were eaten in relatively equal proportions.
25 mm)
Crangon,
gammarid amphipods, and polychaetes were also common prey.
Sizerelated Trends
Three species showed striking changes in diet with size:
melanostictus at 9 and
.
22 m, R. binoculata at 9, 22 and 73 m, and
E. jordani at 73 m.
At the 9 and 22 m station
.
melanostictus was represented in
the catch by two modal size groups (Figure 3 and 4).
A comparison
of diets between the small (< 200 mm) and large (> 200 mm) groups
showed an increase in the proportion of fish in the diet of
Psettichthys with increasing predator size (Table 13).
Mysids
were the most important dietary component of individuals < 200 mm
(73 %), replaced by fish in individuals > 200 mm.
The most common
Table 13.
Percent frequency of occurrence (FO), and average percent
composition by wetweight (WT) of dominant prey in stomachs of
Psettichthys melanostictus less than or equal to and greater than
200 mm standard length (SL) (9 and 22 In stations combined).
SL < 200
n = 31
SL ) 200
= 20
prey taxa
%F0
%WT
%F0
%WT
Mysidacea
83.8
73.0
55.0
34.0
Amphipoda
19.4
2.1
0.0
0.0
6.5
6.5
15.0
3.4
Decapoda larvae
25.8
1.1
0.0
0.0
Osteichthyes
25.8
16.9
60.0
58.7
Crczngon sy Ziros tris
other
-
0.4
-
3.9
43
fish prey identified for
(
.
melanostictus was Microgadus proximus
100 mm).
The dependency of Raja's prey spectrum on size of individual
is outlined in Table 14.
Food habits data from all three stations
were combined, and then grouped by four predator length stanzas.
Crangonid shrimp were the dominant prey of
the two smallest length stanzas (<
.
600 mm).
binoculata within
Small Cancer
magister (< 40 nun), and Ammodytes hexapterus were also common
prey.
Intermediate size R. binoculata (600
799 mm) preyed on a
mixture of Crangon, Cancer, aid small pleuronectiform fish (< 75
mm), primarily ç. stigmaeus.
(870
Skate within the largest size class
1320 mm) consumed large C. magister (90
pleuronectiform (150
130 mm), plus
275 mm) and nonpleuronectiform fishes.
Adult parasitic treniatodes (Otodistomum velii,orum) were
common in the stcinachs of R. binoculata (Table 14).
The amount of
infestation increased with increase in skate length.
Frequency of
infestation and percent composition of parasites by weight of
total stanach contents is reported for the four length stanzas
described above.
Off Oregon, the metacercaria of 0. veliporum are
the most common digenetic trematode parasites of Parophrys vetul
Olson
and presumably other pleuronectiforms (Olson, 1978).
suggests that
.
binoculata become infested with 0.
when feeding on intermediate pleuronectid hosts.
veliporum
Therefore,
trematode infestation may indicate relative importance of
pleuronectids in the diet of a given size class of
binoculata.
R.
Table 14.
Percent frequency of occurrence (FO), and average percent composition by
wet-weight of dominant prey and parasitic Trematoda (Otodistomuin veliporum)
in stomachs of Raja binoculata grouped into four length stanzas:
standard length (SL mm) < 400 (193
599, 600
799, > 800 (870
398), 400
1320).
SL < 400 mm
n = 22
% FO
% WT
prey taxa
599 mm
400
n = 33
799 mm
600
SL > 800 mm
n ± 29
=
9
% FO
% WT
% FO
% WT
% FO
% WT
Cranjon
95.5
74.4
90.9
76.4
79.3
36.4
11.1
1.2
Cancer magister
45.5
11.9
51.5
12.9
62.1
37.0
77.8
45.3
Anirnodytes hexapterus
18.2
1.4
33.3
3.1
34.5
5.9
0.0
0.0
Pleuronectiformes< 60 mm
9.1
3.2
6.1
4.6
58.6
17.8
0.0
0.0
Pleuroiiectiformes > 150 mm
0.0
0.0
0.0
0.0
0.0
0.0
77.8
21.0
3.0
-
2.9
other
Trematoda (0.
9.1
32.5
veliporurn)
% FO and o WT
**
mean number (range),! stomach
4.6
0.4
0.5 (0-1)
48.5
4.2
42.5 (0-241)
93.1
7.3
48.7 (0-136)
100.0
3.2
132.0 (5-244)
** % wet weight composition of all stomach contents, including all unidentified material
45
A size related shift in the diet of E. jordani occurred at
Individuals less than 250 mm fed
approximately 250 mm (Table 15).
on mysids, the sculpin Radulinus asirellus (50 mm), and two
species of recentlysettled, juvenile flatfish:
50 mm) and I. isolepis (25
fed on Crangon and 75
35 mm).
Larger
.
C.
sordidus (30
jordani (> 250 mm)
130 mm juvenile flatfishes, including C.
sordidus, M. pacificus and G. zachirus.
Diet Similarity
Percent similarity values (PS) as a measure of within diet
overlap (wetweight basis) are presented for fish collected at
each station in Tables 16
18.
Percent similarity depends in
part on the taxonomic level used in the comparison.
For fishes
collected simultaneously, overlap measured primarily at the level
of species utilizes all the available information, and therefore
should be a representation of short term or immediate feeding
relationships.
Conversely, diet overlap measured at major
taxonomic levels (e.g.
class, order, etc.) results in a loss of
specieslevel information, but may provide a more general picture
of potential food resource overlap (assuming that species within a
major taxon are equally available).
At all stations, similarities
based on comparisons made at the level of major prey taxa (Tables
16
18, below diagonal) usually were much greater than those at
the lowest taxon (above diagonal).
In general diet overlaps were
highest within the two major feeding types of fishes: 1) those
that preyed on (a mixture of) pelagic and epifaunal prey, and 2)
those that
preyed primarily on infauna (unless otherwise stated,
all overlaps discussed below are based on comparisons made at the
Table 15.
Percent frequency of occurrence (FO), and average percent
composition by wetweight (WT) of dominant prey in stomachs of
Eopsetta jordani less than and greater than 250 mm standard
length (SL) collected at the 73 m station.
SL<
250
SL>
250
n=6
n=23
prey taxa
% FO
% WT
% FO
% WT
Mysidacea
69.6
13.1
0.0
0.0
Crczngon
65.2
18.7
0.0
0.0
Pleuronectiformes < 50 mm
56.5
45.6
0.0
0.0
Pleuronectiformes > 75 mm
4.4
5.7
83.3
76.7
other Osteichthyes < 50 mm
4.4
1.5
16.7
3.1
other Osteichthyes > 75 mm
0.0
0.0.
16.7
18.6
other
-
15.4
-
1.6
Table 16.
Similarity in the diets of eight species of fish collected at the 9 m
station based on percentage of major prey taxa in their diets on a wetweight
basis (lower left), and on percentage of taxa identified to the lowest taxonomic
unit (usually species) (upper right).
c
)çj
S
A
Q\J
S
.
Rczjcz binocul-ata
c.
37
c.
.
.
28
1
30
11
21
0
59
1
29
12
25
2
12
23
11
16
0
9
2
3
0
13
23
0
28
36
Scorpaenichthys marmoratus
98
JIjdro lagus co 1 l-iei
60
60
3
2
i3
Isopsetta isolep-to
29
28
53
22
Psettichthys rnelanostictus
14
14
42
9
38
Micro gadus proxirnus
27
27
43
14
52
71
3
4
4
3
5
54
Platichthjs .stel2atus
Spirinc1us starksi
20
45
-4
Table 17.
Similarity in the diets of ten species of fish collected at the 22 m
station based on percentage of major prey taxa in their diets on a wetweight
basis (lower left), and on percentage of taxa identified to the lowest taxonoinic
unit (usually species) (upper right).
>cp
/
A
"()
.
N
c
,°
.
.
.
.
o
33
Raja binoculata
Hydrolagus colliei
Platichthjs stellatus
55
7
21
2
1
1
18
< 1
<1
7
33
4
1
2
9
2
2
37
12
< 1-
< 1
1-2
20
7
24
2
3
13
12
6
< 1
1
9
< 1
< 1
73
22
50
72
25
50
72
25
30
9
10
28
49
50
2
16
25
43
23
15
< 1
9
2
8
11
4
15
5
80
Microgadus proxirnus
23
27
32
48
21
55
60
AllosI7lerus elongatus
17
15
24
19
2
67
61
64
3
5
12
16
2
76
91
64
Isopsetta isolepis
Parophrjs vetulus
Psettichthys rnelanostictus
Citharichthys stigrnaeus
Spirinchus starksi
60
65
OD
Table 18.
Similarity in the diets of eleven species of fish collected at the 73 m
station based on percentage of major prey taxa in their diets on a wetweight
basis (lower left), and on percentage of taxa identified to the lowest taxonomic
unit (usually species) (upper right).
//
6/
O
C;
c.
Ophiodon elongatus
9
'
I
Q
"ç
V
6;
.°
<1
0
23
24
2
0
0
0
4
<1
14
36
34
2
0
0
I
3
3
1
1
1
0
0
1
1
24
18
6
3
0
2
5
64
<1
2
0
2
20
21
8
0
15
28
18
3
22
28
0
20
21
0
0
Raja rhina
98
Rajcz binoculata
74
77
Citharichthys sordidus
19
22
26
Eopsetta jordani
71
74
88
36
Lepidopsetta bilineata
55
57
74
30
73
Glyptocephalus zachirus
2
4
27
13
19
42
Microstoraus pacificus
0
2
6
6
6
27
64
Pleuronichthys decurrens
0
0
0
1
0
8
21
20
Parophrys vetulus
0
2
3
8
4
26
46
52
56
Isopsetta
4
6
29
13
20
43
72
53
17
isole1yzs
'
26
41
50
lowest taxonomic level).
At the 9 m station, diet overlaps were intermediate within
two groups of fishes:
1) P. melanostictus, M. proximus, and S.
36%), and 2) R. binoculata, H. colliei, and S.
starksi (20
marmoratus (28
59%) (Table 16).
The degree of overlap within the
first group can be attributed to mutual utilization of mysids and
decapod shrimp living both on and above the substrate.
Overlap
within the second group was due to their feeding on Cancer
magister.
The diet of I. isolepis overlapped moderately with all
30%) with the exception of the pelagic feeding
fish collected (9
smelt, S. starisi.
As stated earlier, the species composition of the group of
pelagic and/or epifaunal feeders at the 9 and 22 m stations was
similar except for the addition of C. stigmaeus and A. elongatus
at 22 m.
(22
Maximal values for diet overlaps were somewhat higher
73%) within this group at 22 m when compared to 9 m.
In
part, the higher values reflect a greater utilization of mysids
(primarily
.
kadiakensis) at 22 m.
Diet similarity between small
P. melanostictus and other fishes preying on small pelagic and/or
epibenthic crustacea could be expected to be larger than the
tabulated values because of size related predation on mysids by
melanostictus.
Of the remaining five species, P. vetulus, P.
stellatus, and I. isolepis, all epibenthic and/or infaunal
feeders, showed a low to intermediate degree of overlap (12
37%).
These similarities were the result of consumption of an
assortment of crustacean prey plus Dendraster in the case of ..
isolepis and
.
stellatus.
Intermediate levels of similarity
.
51
were observed between R. binoculata and H. colliel (37%).
Similarities at the 73 m station ranged from 0
64% (Table
18). High diet similarity within the upper left corner of the
table corresponds to those fishes that preyed on juvenile
pleuronectiforms and/or decapod crustaceans (Cancer and Crangon
living on the substrate.
Citharichthys sordidus had more pelagic
food habits than other fishes within this group, and therefore a
lower diet overlap.
Low to intermediate diet overlaps (12
28%)
were observed for the group of fishes which feed primarily on
infauna and appear in the lower right corner of the table (Q.
zachirus, M.
isolepis).
pacificus, P. decurrens, P. vetulus, and I.
For example, P. vetulus and G. zachirus had a diet
overlap of 22%, resulting primarily from consumption of the same
species of polychaetes and especially the amphipods, Ampelisca
macrocephala (Table 11).
Prey Availability
A limited amount of data on available prey exists for the 22
m station from box core and small beam trawl samples that were
collected as part of the Pleuronectid Production Project. These
data will be used to make a qualitative comparison between fish
food habits and the benthic organisms living in each area.
Benthic infauna were sampled within the study area in 25 m
water
depth during July (4 cores), August (4 cores) and October (5
cores) 1978, about a year before the fish collections with a 0.25
m2 box corer (Carey, unpubl. data).
Data from all cores were
summed and are listed as total counts, densities and percent
composition in Table 19.
Sampled seven months prior to the fish
52
Numerical abundance and average percent composition
of invertebrates in box core samples from 22 m station.
Table 19.
TOTAL COUNTS
TAXA
NUMBER/rn2 *
% NUMBER **
saccuZ.ata
Spiophtrnes bombyx
2337
947
23.6
1498
866
15.1
Eohau.storiva sencillus
z4mpeiisca agassizi
1437
702
14.5
716
543
7.2
unident amphipoda
610
-
6.1
Olivella sp.
453
216
4.5
Cuinacea
331
137
3.2
Rhepoxynius vigitegus
216
122
2.2
Nernertea
212
98
2.1
Anrpelisca rnacrocephala
185
112
1.9
7lycinde picta
172
118
1.7
Thalessa spinosa
158
99
1.6
Foxiphalus obtusidens
138
78
1.4
Nephtys caecoides
123
74
1.2
cromiger
101
47
1.0
100
72
1.0
84
49
0.9
Mdibulohoxus unicirostratus
75
39
0.8
Syllidae
75
-
0.8
Phoronida
73
-
0.7
Tellirta rnodesta
62
-
0.6
Anaitides sp.
43
-
0.4
CyZichna attonsa
42
-
0.4
Odostemia sp.
41
-
0.4
Nothricz iridescens
41
-
0.4
Ophiuroidea
40
-
0.4
38
-
0.4
Pelecypoda (unident.)
36
-
0.4
Monoculoides sp1n1pes
36
-
0.4
Spiophes berkeyeyorum
33
-
0.3
Neinatoda
25
-
0.3
Glycinde az'migera
24
-
0.3
Nereis procera
21
-
0.2
!4aalona
Scolop7.os
Dend.raste2' excentricus
Chaetozone setosa
Synchelidium
sp.
53
Table 19 cont'd.
Het.romastus filiformis
20
0.2
Macoma sp.
19
0.2
Phoxocephalidae
18
-
0.2
Pholoe rninuta
17
-
0.2
258
-
2.6
Other
* average for July and August
**
based on total counts
54
Table 20.
Abundance of invertebrates and fishes in beam trawis at
the 22 m station off Moolack Beach on 2 and 29 May 1979.
TAXA
2
% weight
May
% number
29 May
% weight
% number
Invertebrates
Neornys-is kodia7<ensis
Crangon
stylirostris
Crangon franciscorw77
Porcellanidae zoea
Pinnotheridae zoea
C. stulirostris juv.*
Acanthornysis macropsis
Archaeornysis grebniskii
Crangon alaskensis
Clivella sp.
Isaeidae
Pinnotheridae megalops
Acanthornysis davisi
Acanthomysis sculptcz
?anaiius piatycerus
Crangon larvae
25.5
62.1
8.0
<0.1
<0.1
0.3
<0.1
1.1
78.8,
15.4
0.3
0.8
0.9
1.4
0.3
1.1
-
0.4
<0.1
-
87.3
1.6
8.2
0.4
0.1
0.3
<0.1
93.8
0.1
0.1
3.2
1.2
0.3
0.6
-
-
1.4
0.3
0.4
0.5
-
-
-
0.1
0.1
0.1
-
-
0.3
0.3
0.1
2.6
0.1
-
-
-
<0.1
-
0.1
Fis
Citharichths stiamaeus
Parophrys vetulus
Ocella verrucosa
!icroadus proxipus
Isoetta isolepis
Stellerina xyosterna
Psettichthzjs melanostictus
Liaris puZcheilus
Oohiodon eonc7atus
Odontopuxis trispinosa
Allosmerus elonaatus
*juveniles
<20mm
40.5
7.6
20.4
17.1
1.2
5.7
6.8
-
0.7
-
-
26.2
30.7
9.7
5.9
14.4
9.8
1.2
0.7
0.4
0.4
0.4
55
collections, these data give a general representation of the
available prey in the nearshore. Only taxa representing greater
than 0.1% of the numeric total are listed.
A total of 9940
invertebrates representing 75 taxa were sampled.
Polychaetes were
the major group and comprised 50.8% of the organisms sampled.
Of
the polychaetes present, Magelona (23.6%) and Spiophanes bombyx
(15.1%) were numerically dominant.
In addition, Glycinde picta,
Thalanessa spinosa, Nephtys caecoides and Scoloplos armiger were
abundant.
Amphipods were the second most abundant group (34.9%).
The amphipod, Eohaustorius sencillus plus amphipods of the
families Ampeliscidae and Phoxocephalidae were particularly
important.
Caceans were not identified to species, but the
group as a whole ranked seventh in abundance.
Nemertea and
Dendraster excentricus were also important.
A comparison can be made between prey of infaunal feeding
fishes and an estimate of available prey from box core data by
comparing Tables 8 and 19.
For example, six of the ten most
abundant prey in box cores were also abundant in
stomachs.
.
vetulus
This evidence further supports a nonselective feeding
strategy for P. vetulus whereby it utilizes a broad array of
infaunal prey.
The remaining two potential infaunal feeders, P.
stellatus and I. isolepis were more selective and did not utilize
prey in even approximate proportion to their abundance in the box
core sediments.
Beam trawl samples taken in the study area provide
information on available epifaunal prey at the 22 in station.
Epifaunal invertebrates and small fishes were sampled from 18 and
56
22 m water depth on 2 and 29 May 1979 with a 1.5 m beam trawl (6
mm mesh liner) (Krygier and Pearcy, unpubi. manuscr. and data).
Invertebrates and fishes are listed in order of relative abundance
by average percent composition (Table 20).
Neomysis kadiakensis
and Crangon stylirostris were the most abundant invertebrates on a
niimieric and biomass basis.
Juvenile pleuronectiform fishes,
including C. stigmaeus, P. vetulus and I. isolei,is were most
abundant in the beam trawl collections. These flatfishes ranged
in size from 20
agonids (20
50 mm.
Juvenile M. proximus, plus newly settled
40 mm), Ocella verrucosa and Stellerina xyosterna,
were also abundant, and P. melanostictus was common.
Neomysis kadiakensis was an important prey for a large group
of pelagic feeding fishes at the 9 and 22 m stations, including
.
melanostictus, C. stigmaeus and M. proximus, and two osmerids
(Tables 4 and 7).
R.
binoculata fed heavily on the most abundant
of the larger available prey, C. stigmaeus and C. stylirostris
(Tables 5 and 8).
Juvenile M. proximus were abundant in the beam
trawl and an important prey of large P. melanostictus.
The
remaining juvenile fishes: agonids, P. vetulus and I. isolepis
were not found as prey. The number of prey types available to
fishes feeding on or above the substrate appears to be limited,
resulting in the high diet overlaps observed in the pelagic and/or
epifaunal feeders (previous section).
57
DISCUSSION
Fish Assemblages
After studying species composition and relative abundance of
benthic fishes collected in this study, I propose that the
nearshore and midshelf areas off Moolack Beach, Oregon are
characterized by two fish assemblages.
There is justification for
combining information from the 9 and 22
in
station, and considering
fish collected over that depth range as belonging to the same
assemblage.
by
Catches at the two nearshore stations were dominated
. melanostictus and
.
binoculata.
these stations were P. stellatus, I.
colliei, M.
proximus and
.
starksi.
stations was almost identical.
Other fishes common to
isolepis, C. stigmaeus, H.
Catch composition at both
Any differences could be
attributed to the limited number of trawis.
The species composition of benthic fishes found in this study
agrees with the results of earlier studies off Oregon.
Monthly
beam (1.5 in) and otter trawl (7 in) sampling in the same area, over
the same depth range yielded a catch composition that encompasses
both stations (Krygier and Pearcy unpubl. manusc.). The small
sized beam and otter trawis preferentially sampled the smaller
fishes.
Demory et al.
(1976) found I. isolepis, P. melanostictus,
and P. stellatus restricted to shallow depths (< 50 in) and sand
sediments in his 1971
1974 otter trawl surveys over the entire
width of the Oregon shelf from the Columbia River to Cape Blanco.
The midshelf assemblage discussed in this paper corresponds
to a 74
102 in "sandy bottom" assemblage, dominated by C.
sordidus, and observed off Heceta Head, Oregon by Pearcy (1978).
58
Other important members of Pearcy's assemblage were
and
.
pacificus.
vetulus, G.
zachirus
.
Demory et al. (1976) found C. sordidus, P.
zachirus, E. jordani, Raja sp., H.
c.olliei, M.
pacificus, and Squalus acanthais (spiny dogfish) to constitute a
midshelf (35 - 110 m) assemblage in areas of sand with a low
"mud content".
In analysis of west coast fish assemblages based
on National Marine Fisheries Service groundfish survey data,
Gabriel (1983) identified an Oregon midshelf assemblage area
extending from Cape Falcon to near Coquille Point, Oregon at an
average depth of 113 m.
The catch in this region was dominated by
Merluccius productus (Pacific hake).
Other common (FO > 50%)
members of the assemblage were G. zachirus, M. pacificus,
Thaleichthys pacificus (euchalon), E.
jordani, P. vetulus,
Atheresthes stomias (arrowtooth flounder), and C. sordidus.
The
high vertical opening NMFS groundfish survey net was rigged with
roller gear.
This type of net design is selective for
nektobeuthic fishes and selective against flatfishes.
Therefore,
the type of gear used could account for the dominance of
.
productus observed by Gabriel.
How does the size spectriun of fishes representing the two
assemblages in the current study compare to the commercial
fishery?
The nearshore area is not a typical fishing ground.
Pleuronectid fishes from the nearshore assemblage covered a broad
size range, including both juveniles and commercial sized adults.
With the exception of P. vetulus, pleuronectid fishes collected at
the 73 m station were generally smaller (150
250 mm) than those
targeted in the commercial fishery (Alverson et al. , 1964; Barss,
59
1976; Hosie, 1976; Eyck and Demory, 1975).
Regions of high catch
for commercially important flatfishes are located to the south in
the vicinity of Heceta Bank, to the north off the Columbia River,
and generally further offshore.
However, the fishery for
vetu].us is centered at midshelf.
In addition, E.
.
jordani and M.
pacificus are fished seasonally at midshelf depths (Hewitt,
1980).
Food Habits
The fishes examined from both the nearshore and midshelf
areas form a continuum between two extremes in feeding types:
fishes that prey solely on pelagic invertebrates and fishes, and
fishes that feed exclusively on infaunal invertebrates including
polychaetes, amphipods, cumaceans, and molluscs.
Between these
two extremes are fishes which eat varying proportions of epifaunal
prey including both invertebrates and fishes.
As collections were
obtained with bottom trawls it is important to emphasize that all
fishes examined have benthic or nektobenthic affinities.
For pleuronectiform fishes, de Groot (1971) developed three
major feeding types based on digestive system morphology
(esophagus and stomach, intestinal loop, and gill rakers) and
direct observations of food habits:
fish feeders (type I),
crustacean feeders (type II) and polychaete - mollusc feeders
(type III).
In an earlier study, Hatanaka et al.
(1954) after a
study of mouth parts, characterized pelagic feeding species as
having large symmetrical jaws (directed forward) with well
developed teeth on both blind and eyed sides (often with a double
row on the upper jaw), large stomachs, short intestines, and large
gill rakers.
Tsuruta and Omori (1976)
expanded on the work of
Hatanaka et al., and arrived at a set of feeding types, similar to
those of de Groot based on mouth morphology and behavior.
were pelagic, epibenthic and infaunal feeders.
These
They observed that
the mouths of some pelagic feeding flatfishes are asynmmetrical
upward (Tsurata and Omori, 1976).
In contrast, flatfishes that
feed on infauna have small asymmetrical jaws directed toward the
blind side (where teeth are more developed), small stomachs, long
intestines (complicated intestinal loop), and small gill rakers.
It is not uncommon for these infaunal predators to have teeth
limited almost entirely to the blind side ( Hatanaka et al.,
1954).
In the current study, the mixed pelagic and epibenthic
feeding E. jordani, C.
sordidus, C. stigmaeus, and P.
melanostictus have large, almost symmetrical mouths with well
developed teeth on both sides of the jaw, large stomachs, simple
looped intestines, and large gill rakers (Clemens and Wilby, 1967;
Hart, 1973; and Wakefield,personal observation).
Parophrys
vetulus, M. pacificus, 6. zachirus, and P. decurrens fall into the
infaunal feeding group (de Groot's type III) having small,
asymmetrical, downwarddirected mouths, teeth limited to the blind
side, long intestines and small gill rakers (Clemens and Wilby,
1967; Hart, 1973; Wakefield, personal observations).
Lepidopsetta
bilineata, P. stellatus, and I. isolepis are intermediate between
both groups, but lie closer to the infaunal feeding group.
These
species have a small asymmetrical mouth directed only slightly
downward, moderately sized stomach and intestines (a tubular gut
61
in the case of P. stellatus), and stout gill rakers.
Isopsetta
isolepis and P. stellatus have short but well developed teeth on
both sides of the head, whereas L.
the blind side.
bilineata has teeth limited to
The above three species appear to fall into the
intermediate catagory of epibenthic feeder (or de Groot type II).
The Food Habits of Nearshore Benthic Fishes
Few studies have been published on the biology of nearshore
opencoast fishes in the northeast Pacific.
Ambrose (1976) (see
also Cailliet et al., 1979) studied the food habits of four
pleuronectiforms (P. vetulus, C. stigmaeus,
P.
P.
melanostictus and
stellatus) at a nearshore station near Monterey, California.
The food habits of these four species were very similar to those
collected in the nearshore off Moolack Beach.
Psettichthys
melanostictus and C. stigmaeus both consumed pelagic mysids, and
in the case of C. stigmaeus, motile epibenthic amphipods.
At both
Moolack Beach and the Monterey site piscivory increased with size
in P. melanostictus.
Similarily P. stellatus, both off Monterey
and Oregon fed on polychaetes, decapod crustaceans, and pelecypod
siphons.
The results of Ambrose (1976) and the current study
characterize P. vetulus as a nonselective generalist, feeding on
a diverse spectrum of infaunal polychaetes, amphipods, cumaceans,
whole (and siphons of) pelecypods.
Rogue and Carey (1982) found that juvenile flatfishes (17
88 mm)
(P. vetulus, I.isolepis, C. stigmaeus and P.
melanostictus) fed on different specific food items at the
nearshore Moolack Beach site, however, the functional feeding
relationships for the juveniles mirrored that of the adults,
62
Cropped off body parts
ranging from pelagic to infaunal feeders.
were also an important prey of juvenile
isolei,is.
.
vetulus and I.
Cropping of tissue that can regenerate has been
documented in the nearshore areas of the North Sea for
Pleuronectes platessa, and Platichthys flesus.
Both ate pelecypod
siphons (Tellina) and Arenicola "tails" (Trevallion, 1971; de
Vlas, 1979).
Pleuronectes platessa and Platichthys flesus are
very similar in body morphology, general biology and food habits
to the North Pacific Paroprhys vetulus and Platichthys stellatus,
respectively. Both of these species share pelecypod siphons as a
major prey group.
Of the nonpleuronectiform fishes studied here, big skate, R.
binoculata, and the chimarid, H. colliei, were abundant and
composed much of the fish biomass at the nearshore stations.
Raja
binoculata consumed primarily decapod crustaceans and
pleuronectiforms.
Hart (1973) lists crustaceans and fishes as
primary food for R. binoculata.
McEachran et al.
(1976) studied
feeding relationships within two coOccurring species pairs of
in the North Atlantic.
One species pair, R.
radiata and R.
senta fed heavily on decapod crustaceans and euphausiids, but
included some fishes as a secondary component of their diet.
Most
of northeast Atlantic skates (12 species) feed primarily on
decapod crustaceans (both shrimps and crabs) and fishes including
flatfishes (Wheeler, 1969).
The largest northeast Atlantic skate,
R. batis, attains the size of R.
binoculata, is similar
morphologically, and feeds mainly on fishes with decapods as a
secondary component (Wheeler, 1969).
63
Hydrolagus colliei stcinachs contained a large proportion of
shell fragments and unidentifiable welldigested material.
At the
9 and 22 m stations, Hydrolagus fed on molluscs, crangonid shrimp
and fish (mainly C. stigmaeus).
Johnson and Horton (1972) had
similar findings in their analysis of
four locations off Oregon.
H. colliei food habits from
Of the identifiable material, shrimp,
molluscs and echinoderms were principal prey.
The Food Habits of Midshelf Benthic Fishes
The majority of benthic fish food habits studies off Oregon
have emphasized mid and outer continental shelf areas and focused
on pleuronectiform fishes (Pearcy and Vanderploeg, 1973, Kravitz
et al., 1977; Pearcy and Hancock, 1978 and Gabriel and Pearcy,
1981).
In combination, these studies provide information for
comparison with the current study site at midshelf.
Generally,
the above investigators recognized the same feeding types, pelagic
and benthic, but there were some differences in their results.
Kravitz et al. (1977) examined stomachs of P. vetulus, G.
zachirus, L. bilineata, E. jordani and C. sordidus from a 95 - 106
in station in close proximity (44°42' N, 124°24') to my 73 m
station.
The diet of E. jordani, a pelagic and/or epibenthic
feeder in the current study, was similar to the observations of
Kravitz et al. (1977), but differed as far as prey types.
In both
studies, E. jordani fed on juvenile flatfishes, other beuthic
fishes, decapod crustaceans, and mysids.
Engraulis mordax
(northern anchovy) was an important prey of C. sordidus (Kravitz
et al., 1977; see also Barss, 1976), where as, pelagic
invertebrates and recently settled I. isoplepis were important in
64
the current study.
Of the infaunal feeders studied by Kravitz et al. (1977), P.
vetulus had the most diverse diet, including 63 prey taxa.
The
amphipod Ampelisca macrocephala had the highest frequency of
occurrence for both studies (60 and 63%).
current study,
.
In both that and the
vetulus consumed primarily polychaetes and
amphipods, and each individual stcxiach contained many different
prey taxa.
Glyptocephalus zachirus, another infaunal feeder,
showed the same pattern, but with amphipods as dominant prey and
polychaetes secondary in importance.
Amphipods were also the
primary prey of M. pacificus at the midshelf station.
However,
near Heceta Bank, Pearcy and Hancock (1978) found polychaetes to
be the major prey of
.
pacificus and
.
zachirus at their deeper
stations (100 - 195 m), where as amphipods were secondary.
In a
separate study on feeding selectivity, Gabriel and Pearcy (1981)
observed that polychaetes, ophiuroids and molluscs were the most
important prey of M. pacificus with positive selection for
polychaetes and ophiuroids.
Although this collective evidence
shows these fishes feeding on the same general types of infauna,
diet overlaps between species were low.
The diet of L. bilineata differed between the current study
and that of Krasritz et al.
(1977).
Principal prey of L.
bilineata at the 73 m station were recently settled flatfishes,
where as in the earlier study ophiuroids were the principal prey.
Shubnjj.son and Lisovenko (1964), and Forrester and Thomson (1969)
both describe L.
bilineata as feeding on a combination of benthic
invertebrates and fishes.
65
In a comprehensive study of softbottczn fish communities of
the Southern California Bight, Allen (1982) placed P. vetulus, M.
tacificus and G. zachirus into three different feeding guilds.
He
based his conclusion on morphology, stanach content analysis, and
prey availability.
M. pacificus was classified as a visual
"extracting benthivore", P. vetulus as a "excavating
benthivore", and G. zachirus as a "nonvisual benthivore"
(utilizing subdermal sense organs located on the head).
All of
the above observations indicate that food resources are
partitioned among these benthophagus fishes.
In general, the results of this study show similar food
habits to previous studies, especially at the level of major prey
groups.
Its limitation is that sampling for food habits was
restricted to a single portion of the coast, and to a single day.
The lack of seasonal, bathymetric, and coast wide coverage as well
as interannual differences could account for some of the
differences between the current study and and those studies cited
above.
If combined, however, past and current results are useful
in examining trophic relationships between the benthic fishes
studied.
This is demonstrated below.
Trophic Relationships
Food webs have been constructed for both the nearshore and
midshelf fish assemblages, synthesizing information from the
current study, previously cited literature and unpublished
information on the distribution and food habits of northwest
coastal fishes.
A general view of feeding relationships within
the meio and macrobenthic invertebrate community is derived from
review of the literature (Arntz, 1978; Barnes, 1980; Fenchel,
1978; Fenchel and Jørgensen, 1977; Jones, pers. comm.; Mills and
Fournier, 1979; Simenstad et al., 1979; Tyler, 1974)
A partial food web for the nearshore benthic enviromient is
depicted in Figure 7.
food resource linkages.
The transfer arrows in the diagram signify
Relative importance of each linkage is
indicated by the type of line.
The nearshore habitat is a high
energy wave zone, characterized by a well sorted sand substrate.
Production in this enviroimient is based on phytoplankton, benthic
Energy
microalgae, and terrestrial and aquatic organic detritus.
flows from detritus and phytoplankton through bacteria and/or
meiofauna to macroinfauna and epifauna, and in turn to the
benthic fishes (generally three or four trophic levels). The food
web identifies the importance of the nearshore open coast as a
nursery area for four pleuronectiforms plus juvenile M.
Engraulis mordax, osmerids and agonids.
proximus,
As stated earlier,
feeding relationships within the group of zeroage flatfishes is
functionally similar to the adults inhabiting the same area.
A diverse group of macroinvertebrates are prey to
benthophagus fishes feeding within the sediment and at the
sedimentwater interface of the nearshore.
Major prey items are
polychaetes, nemerteans, amphipods, caceans, molluscs and
echinoderms.
Two crustaceans, Crangon and Cancer, plus juvenile
pleuronectiforms and Ammodytes hexapterus are important epibenthic
prey of the skate, Rala binoculata.
The chimarid, Hydrolagus
colliel, has similar food habits. Dietary differences exist within
I
,, Hbo.]
[
LIL
7
- - -0.
5
25%
26-50%
I 51
Figure 7.
Diagram of bcnthjc food web in the nearshore area off Moolack Beach, Oregon.
Transfer arrows indicate food resource linkages (see text for description).
100%
the group of benthophagus fishes, and these differences are
consistant with other studies.
In addition, these dietary
differences show a relationship to patterns in functional
Platichthys as a polychaete
morphology (eg.
mollusc feeder and
sc*newhat of a specialist, vs Parophrys as a polychaete feeder and
a generalist).
For any given species, comparisons between areas
indicate that these fish are each enough of a generalist to alter
their predatory tactics to utilize the available prey.
A second group of fishes feeds primarily at the interface or
in the water column in close association with the substrate.
Mysids (and to a lesser extent Crangon) were the dominant prey of
this group.
These detritivoreherbivore crustaceans represent a
major linkage in the nearshore food web.
Two pelagic osmerids,
cmon nearshore fishes, also fed heavily on this resource.
Food
resource overlap within the group of pelagic and/or epibenthic
feeders was high.
Mysids and Crangon are known to be very
abundant year round in the nearshore area, and this may explain
their large proportion in the diets of so many fishes.
In terms
of resource partitioning, high diet overlaps may occur when
resources are abundant; conversely, during periods of reduced food
availability, overlap may be low (Zaret and Rand, 1971;
MacPhearson, 1981).
The midshelf food web appears in Figure 8.
This area is
also characterized by a sand substrate, but the mud content is
greater.
The beuthic invertebrate community as well as the
resident fish assemblages are quite different from the nearshore
shelf area.
As in the case of the nearshore, the midshelf (in
[a
/
27 \-
0
.a
-
k
N
-.
J
\ I
't-
/
)1-.c
, - -
ri-i.
/
1I
/
M
..'L
7===
-v
I
I
1
1
-
/
I
I
/ -
..-
_----
%
if
r /
f
/
/
,/ \4
;.,d
-
a..
N
lb
2:1
51-100%
Figure 8.
Diagram of benthic food web in the midcontinental shelf area off Moolack
Beach, Oregon. Transfer arrows indicate food resource linkages (see
text for description).
m
t'D
70
combination with the outershelf) is probably a major nursery for
resident flatfishes (Pearcy et al., 1977; Demory et al., 1976).
The overall trophic structure is similar to that of the
nearshore, based on phytoplankton and detritus with fishes
occupying third and fourth trophic levels, but there are
differences which are apparent in the two food webs (Figures 7 and
8).
The pelagicfeeding Citharichthys sordidus is a dominant
feature of the inidshelf.
Two additional pleuronectids and three
species of Raia prey heavily on juvenile to subadult
pleuronectiforms plus epibenthic decapods.
Although Raja was not
very abundant in the current study, other investigators have found
it to be abundant in midshelf areas (Gabriel, 1983; Demory et
al., 1976).
Mysids, a major epibenthic food resource is less
important here, while Crangon continues to be an important prey.
Infaunal feeding fishes are more numerous in number and
species at the midshelf.
catches.
Six pleuronectiforms dominated the
Diet overlap within the group of infaunal feeders was
low to intermediate.
Dietary differences do exist within this
group of benthophagus fishes, and these differences show a
relationship to patterns in functional morphology.
These
functional differences permit enough flexibility for fishes to
alter their predatory tactics to utilize available prey.
The
observed overlap was probably a result of a combination of
distinct feeding types and the diverse nature of the available
prey.
71
Concluding Remarks
This study of benthic fish feeding relationships builds on
the existing biological information and fills information gaps on
trophic structure.
The food web analysis points to the complexity
of the system and diverse nature of potential interactions within
the shelf community.
Interactions occur in many segments of the
community, but those most conspicuous are in the areas of food
resource overlap, and predation among species which are part of
the same multispecies fishery.
During periods of food resource limitation, competition
between cooccurring fishes could reduce fish growth rates and/or
reproductive output.
Of the eleven flatfishes examined as part of
the current study, four benthic feeding flatfishes had
intermediate diet overlaps:
pacificus and G. zachirus.
P.
vetulus, I. isolepis, M.
Of these four, M. pacificus and G.
zachirus have the broadest overlapping depth range (Alverson et
al., 1964), and cooccur as important components in the
multispecies trawl fishery on the Oregon shelf.
These two
flatfishes could potentially interact trophically to limit one or
the other's production.
At shallower depths, the commercially
important P. vetulus and noncommercial flatfish, I. isolepis, co
occur over a broad shallow to intermediate depth range, and
throughout both juvenile and adult life history stages.
These two
species might also compete for food resources during periods of
food limitation.
A diverse group of fishes were identified as potential
predators on flatfishes, including, at the midshelf station, L.
72
bilineata, E.
and R. rhina.
jordani, 0. elongatus, and two skates, R. binoculata
Many of the flatfishes consimied were commercially
important species.
juvenile
.
In the nearshore area, R. binoculata preyed on
stigmaeus, a noncommercial bothid.
Raja binoculata
might be an important predator on other juvenile flatfishes
utilizing the nearshore nursery area.
range of the flatfishes eaten (20
In general, the broad size
250 mm) suggests that this
source of mortality to pleuronectiforms would not be limited to a
single time period during settlement.
In addition, skates appear
to be a predator on the commercially important crab, Cancer
rn!ister.
The large number and biomass of skates known to inhabit
the nearshore and midshelf indicates that this little studied
group may play an important role in the continental shelf benthic
community as a dominant predator. Additional coast wide studies
during all seasons are needed to identify the importance of these
predators in contributing to flatfish and Dungeness crab
mortality.
'-5
B IBLIOGRAPHY
Allen, M. 1. 1982. Functional structure of softbottom fish
Ph.D. Thesis, Univ.
communities of the southern California shelf.
of California San Diego, La Jolla, CA. 576 p.
A study
1964.
Alverson, D. L., A. T. Pruter and L. L. Ronholt.
of demersal fishes and fisheries of the northeastern Pacific
H. R. MacMillan Lectures in Fisheries, Inst. Fish., Univ.
Ocean.
of British Columbia. 190 p.
The distribution, abundance, and feeding
1976.
D. A.
Ambrose
ecology of four species of flatfishes in the vicinity of Elkhorn
San lose,
Slough, California. M.S. Thesis, San lose State Univ.,
CA.
121 p.
,
Arntz, W. E. 1978 The "upper part" of the benthic food web:
Rapp. P.v. Reun
the role of macrobenthos in the western Baltic.
mt Explor. Mer. 173:85-110.
Cons.
Barnes, R. D. 1980. Invertebrate Zoology. W. B. Saunders
Phila.
743 p.
College/ Halt, Reinhart and Winston.
The English sole.
1976.
Barss, W. H.
76-1.
Inform. Rept.
Oregon Dept. Fish Wildi.
An ordination of the upland
1957.
Bray, I. R. and 3. T. Curtis.
27:325Ecol. Mouogr.
forest communities of southern Wisconsin.
349.
Several approaches to feeding ecology of
Cailliet, G. M.
1977.
Fish Food
In C. A. Simenstad and S. I. Lipovsky (eds.)
fishes.
1st
Pac. Northwest Workshop, October 13-15,
Habits Studies. Proc
Seattle.
Univ.
Wash.
Press.
1976, p.1-13.
Trophic
1979.
Cailliet, G. M., B. S. Antrim, and D. B. Ambrose.
Slough
and
nearby
waters.
spectrum analysis of fishes in Elkhorn
Fish Food
In R. S. Lipovsky and C. Simenstad (eds.) Gutshop '78:
2nd
Pac.
Northwest
Workshop,
October
10-13,
Proc.
Habits Studies.
Seattle.
1978, p.118-128. Univ. Wash. Press.
unpubl. data.
Carey. A. G.
Univ., Corvallis, OR.
School of Oceanography, Oregon State
Fishes of the Pacific
1967.
Clemens, W. A. and G. V. Wilby.
Fish.
Res.
Bd.
Can.
Bull.
68. 443 p.
coast of Canada.
Demory, R. L., M. I. Hosie, N. T. Eyck, B. 0. Forsberg. 1976.
Marine resource surveys on the continental shelf off Oregon, 1971
49 p.
Oregon Dept. Fish. and Wildl. Compl. Report.
1974.
Eyck, N. Ten and R. L. Demory. 1975. Utilization of flatfishes
16th Annual
caught by Oregon trawlers in 1974. Prepared for the
Meeting of the Technical Subcommittee of the International
74
Groundfish Committee.
6 p.
Ann.
Fenchel, T. M. 1978. The ecology of micro and meiobenthos.
9:99-121.
Rev. Ecol. Syst.
Detritus food chains
1977.
Fenchel, T. M. and B. B. JGrgensen.
the role of bacteria. Adv. Microb. Ecol.
of aquatic ecosystems:
1:1-58.
Population studies on
1969.
Forrester, C. R. and 3. A. Thomson.
the rock sole (Lepidopsetta bilineata) of northern Hecate Strait,
Fish. Res. Board Can., Tech Rep. 108. 104 p.
British Columbia.
Structure and dynamics of northeastern
1983.
Gabriel, W. L.
Ph.D. Thesis, Oregon State
Pacific demersal fish assemblages.
298 p.
University, Corvallis, OR.
Preliminary analysis of
1980.
Gabriel, W. L. and A. V. Tyler.
March
Mar. Fish. Rev.
Pacific coast demersal fish assemblages.
April :83-88.
Feeding selectivity of
1981.
Gabriel, W. L. and W. G. Pearcy.
Dover sole, Microstomus pacificus, off Oregon. Fish. Bull.
79: 749-764.
Groot, S. 3. de 1971. On the interrelationships between
morphology of the alimentary tract, food and feeding behavior in
Neth. I. Sea Res.
flatfishes (pisces: Pleuronectiformes).
5:121-196.
Goals and objectives of fishery management.
1977.
Gulland, 3. A.
FAO Tech. Paper 166. 14 p.
Objectives and problems related to
1974.
Harden Jones, F. R.
F. R. Harden Jones (ed.), Sea
In.
research into fish behavior.
John
Wiley and Sons, New york.
Fisheries Research, p. 261-275.
Pacific fishes of Canada.
1973.
Hart, 3. L.
Bull. 180. 740 p.
Can.
Fish. Res. Board
1954.
Hatanaka, M., M. Kosaka, Y. Sato, K. Yamaki, and K. Fukui.
Interspecific relations concerning the predacious habits among
benthic fish. Tohoku 3. Agric. Res. 5:177-189.
Direct observation of the behavior of fish
in relation to fishing gear. Helgolander Wissenschaftliche
24: 348-360.
Untersuchungen.
Hemniings, C. C. 1973.
Seasonal changes in English sole
1980.
Hewitt, G. R.
an analysis of the inshore trawl fishery off
distribution:
Oregon. M.S. Thesis, Oregon State University, Corvallis, OR.
p.
Hogue, E. W. and A. G. Carey.
1982.
Feeding ecology of 0age
59
75
flatfishes at a nursery ground on the open Oregon coast.
80:555-566.
Bull.
The rex sole.
1976.
Hosie, M. 3.
Fish and Wildl.
5 p.
Fish.
Inf. Rep. 76-2, Oregon Dept.
A systematic study of the Oregon
1981. Flatfishes:
Jackson, C.
pleuronectid production system and its fishery. Oregon State
39 p.
University Sea Grant (OREStJT-81--OO1).
Lewngthweight
1972.
Johnson, A. G. and H. F. Horton.
relationship, food habits, parasites, and sex and age
determination of the ratfish, Hydrolaaus colliei (Lay and
70:421-429.
Fish. Bull.
Bennett).
pers. comm.
Jones, H.
Univ., Corvallis, OR.
School of Oceanography,
Oregon State
Food of five
1977.
Kravitz, M. 3., W. G. Pearcy, and M. P. Gum.
species of cooccurring flatfishes on Oregon's continental shelf.
Fish.
Bull.
74:984-990.
Distribution,
unpubl. manuscr.
Krygier, E. T. and W. G. Pearcy.
abundance, and growth of 0age English sole in estuaries and along
the importance of estuarine nursery grounds.
the coast of Oregon:
School of Oceanography, Oregon State Univ., Corvallis, OR.
School of
unpubi. data.
Krygier, E. T. and W. G. Pearcy.
Oceanography, Oregon State Univ., Corvallis, OR.
Kuim, L. D., R. C. Roush, 3. C. Harlett, R. H. Neudeck, D. M.
Chambers, and E. 3. Runge. 1975. Oregon continental shelf
sedimentation: interrelationships of facies distribution and
83:145-175.
Geol.
sedimentary processes. 3.
Lodge, D.
pers. comm.
Clatsop Community College, Clatsop, OR.
A study of fish capture
1981.
Main, 3. and G. I. Sangster.
process in a bottom trawl by direct observation from a towed
23.
Scot. Fish. Res. Rep.
24 p.
underwater vehicle.
Resource partitioning in a mediterranean
1981.
MacPhearson, E.
4:183-193.
Mar. Ecol. Prog. Ser.
demersal fish community.
Food
1976.
division within two sympatric speciespairs of skates (Pisces:
35:301-317.
Biol.
Rajidae). Mar.
McEachran, 3. D.,, D. F. Boesch, 3. A. Musick.
Some environmental consequences of vertical
1970.
Miller, C. B.
15:727-741.
Limn. Oceanogr.
migration in marine zooplankton.
Fish production and the
1979.
Mills, E. L. and R. 0. Fournier.
marine ecosystems of the Scotian shelf, eastern Canada. Mar.
54:101-108.
Biol.
76
Parasitology of the English sole, Parophrys
Olson, R. E.
1978.
I. Fish Biol. 13:237-248.
vetulus Girard in Oregon USA.
Distribution and abundance of small
flatfishes and other demersal fishes in a region of diverse
76:629-640.
Fish. Bull.
sediments and bathymetry of f Oregon.
Pearcy, W.
0.
1978.
Radioecology of
1973.
Pearcy, W. G. and H. A. Vanderploeg.
In Radioactive contamination of the
benthic fishes off Oregon.
marine environment, p. 245-260.
Pearcy, W. G., M. I. Hosie and S. L. Richardson. 1977.
Distribution and duration of pelagic life of larvae of Dover sole,
Microstomus pacificus; rex sole, Glyotocephalus zachirus; and
petrale sole, Eopsetta jordani, in waters off Oregon. Fish. Bull.
75:173-183.
Pearcy, W. G. and D. Hancock. 1978. Feeding habits of Dover
sole, Microstomus pacificus; rex sole, Glyptocephalus zachirus;
slender sole, Lyopsetta exilis; and Pacific sanddab, Citharichthys
sordidus, in a region of diverse sediments and bathymetry off
75:173-183.
Fish. Bull.
Oregon.
Growth of juvenile English sole,
1982.
Rosenberg, A. A.
Parophrys vetulus, in estuarine and open coastal nursery grounds.
80:245-252.
Fish. Bull.
Sediment textures and internal structures:
1970.
Roush, R. C.
comparison between central Oregon continental shelf sediments and
adjacent coastal sediments. M.S. Thesis, Oregon State Univ.,
Corvallis, OR.
75 p.
a
Data on the biology
1964.
Shubnjlson, D. A. and L. A. Lisovenko.
Tr.
Vses. Nauchnoof rock sole of the southeastern Bering Sea.
(Izv.
Tik.hookean.
49
Inst.
Morsk.
Rybn.
Khoz.
Okeanogr.
issled.
209-214.
51)
Nauchno-issled. Inst. Morsk. Rybn. Khoz. Okeanogr.
Simenstad, C. A., B. S. Miller, C. Y. Nyblade, K. Thornburgh, L.
Food web relationships of northern Puget
1979.
J.
Bleclsoe.
Sound and the Strait of Juan de Fuca: A synthesis of available
EPA-600/7-79-259.
334 p.
knowledge.
III.
Studies on Tellina tenuis da Costa.
Trevallion, A.
1971.
3. exp. mar. Biol.
Aspects of general biology and energy flow.
7:95-122.
Morphological characters of the
1976.
Tsurata, Y. and M. Omori.
oral organs of several flatfish species and their feeding
Tohoku I. Agr. Res. 27:92-114.
behavior.
In R. 0. Brinkhurst
Community analysis.
Tyler, A. V. 1974.
St. Martin's Press.
The Benthos of Lakes.
p. 65-83.
(eds.)
Y.
N.
77
In press.
Tyler, A. V., W. L. Gabriel and W. I. Overholtz.
Adaptive management based on structure of fish assemblages of
Ca. 3. Fish. Aquat. Sd.
northern continental shelves.
Vias, 3. de. 1979. Annual intake of plaice and flounder in a
tidal flat area in the Dutch Wadden Sea, with special reference to
consumption of regenerating parts of macrobenthic prey. Neth. 3.
13:117-153.
Sea Res.
The fishes of the British Isles and Northwest
1969.
Wheeler. A.
East Lansing.
613 p.
Europe. Michigan State Univ. Press.
Competition in tropical
1971.
Zaret, T. M. and A. S. Rand.
support
for
the
competitive
exclusion principle.
stream fishes:
52:336-342.
Ecol.
APPENDICES
Appendix I.
Summary of food habits data collected for Psettichthys
melanostictus, sand sole; Microgadus proximus, Pacific
toincod; and Spirinchus starksi, night smelt, collected
at the 9 m station, May 1979 (FO = frequency of
wetweiught, # = number).
occurrence, W
Appendix I.
Psttichthy8
%0
tW
Spirincthus
ato.<ksi
Microg4dua
proxitriva
meianostictu3
%
Po1ycheta
SF0
SW
20.0
3.2
-
20.0
7.4
1.4
60.0
40.0
60.0
20.0
13.8
2.9
1.9
20.8
8.6
2.5
2.9
s
SF0
SW
St
20.0
20.0
25.0
37.6
Gastropoda
Oil vldae
Oli,ella sp.
Malacostraca: Peracarida
Mys I dacea
A,anthomjei daviii
A<anthonyaia sculpta
35.5
19.4
38.7
11.8
1.7
/.8
2.5
6.8
Neonyeia !cadiakenaia
Neosnyaie rayit
58.1
16.1
24.3
2.1
25.4
2.5
20.0
13.3
2.9
40.0
20.0
20.0
25.0
20.0
3.2
<0.1
2.2
20.0
<0.1
<0.1
20.0
2.2
2.0
20.0
2.8
1.4
40.0
2.4
8.6
40.0
1.2
11.1
20.0
0.7
29
40.0
19.3
13.0
20.0
2.7
10.0
Mysldae
<1r,hd.anraia grebnitakii
12.5
10.3
Paiphipoda
Gau,naridea
Peqel Iscidee
Mq,elieca maarocephala
Atylldae
AtyiUe sp.
16.1
2.2
4.4
Oedicerotldae
SynaheUdiwn ahoemakeri
Phoxocephal ldae
?.&1udibu )5<J.U8
unjoiroatratus
Malacostraca: Eucarida
Decapoda
Caridea
Crangonldae
CIrnl<m atyiiroøtris
Brachyura
Brachyura megalops
19.4
9.3
7.4
6.5
2.5
2.1
22.6
1.1
5.8
Cancrldae
cancer "sigi step
20.0
5.5
10.0
Appendix I cont'd.
1.ettichthya
me lanoatictua
FO
SW
S#
Microgadus
proximus
SF0
SW
S#
20.0
0.1
2.9
20,0
16.9
3.2
SpirinchuB
atark8i
SF0
SW
SI
20,0
18.0
Anomura
Porcel lanidae
Porcellanidae zoea
Porcel lanidae magalops
Ostel chthyes
AirndytIdae
4.io8jtco
xopterzw
3.2
3.1
3.3
35. 5
31 .6
23.3
3.2
1.2
0.9
3.2
0.1
0.8
11,8
Gadidae
Microadua preiniva
Bothidae
Cithcwiohthya
DtJfl&2CuB
Pleuronectidae
unidentified material
12.3
13.1
0.0
LE
81
Appendix II.
Summary of food habits data collected for Isopsetta
isolepis, butter sole; Platichthys stellatus, starry
flounder; Scorpaenichthys marmoratus, cabezon; Raja
binoculata, big skate; and Hydrolagus colliei, ratfish,
collected at the 9 m station, May 1979 (FO = frequency
of occurrence, W = wetweight, /1 = number).
Appendix II.
Platichthya
rsopaetta
isolepia
Polychaeta
SF0
SW
SI
20.0
6.0
-
SF0
SW
Raja binoculata
night
Scor'paenichthyB
ateliatua
SI
max,noratua
SW
SI
SF0
SF0
day
SW
SI
SF0
SW
Ilydrolagus
colliei
SI
SF0
SW
SI
7.7
0.1
-
23.1
10.8
5.1
15.4
7.7
0.1
0.4
2.0
4.2
1.7
0.1
1.2
23.1
0.4
11.2
Sigal lonldae
St$wnalaia tertiaglabra
11.3
0.2
1.1
11.1
0.1
3.1
OnuiThidae
Nothria irideecena
30.0
22.7
20.9
Gas tropoda
01 ivldae
Oli'.lla Sp.
Nassarildae
33.0
Naaaapiva foaaatua
0.1
3.0
Pe 1 ecypoda
Solenldae
Siliqua pat4Za
)iiiqsa patula siphon
44.4
45.2
35.8
Octopoda
4.5
2./
1.5
4.5
2.1
1.5
13.1
0.1
0.8
Hal lacostraca: Peracarida
Mysidacea
Mysldae
11.1
Aaanthornyaia dauiai
Archaeomyaia grebni taki I
eO.l
0,1
33.3
NeorniJBia Ia54ii
1.5
1.0
Isopoda
Idote idae
.'..ynidotea
11.1
sp.
0.1
0.1
hiiphipoda
iajiiiiiaridea
10.0
0.9
1.3
20.0
1.9
12.4
33.3
24.3
32.8
10.0
0.4
1.8
11.1
0.3
0.1
10.0
5.2
5.5
11.1
<0.1
3.1
1.7
<0.1
0.6
Atyl idae
Atylua tridena
Lysanassdae
1!ipponcdon
deut<zculatu.
Phoxoceptiafldae
Appendix II cont'd.
I8opJetta
iaolepi8
SW
SF0
Scorpaeniuhthya
marmoratua
Platiahthya
Btellatua
SI
510
SW
SI
SF0
SW
SI
66.1
34.9
13.0
33.1
0.1
3.5
100.0
61.1
67.8
33.3
1.5
1.8
day
SF0
Raja binooulata
night
W
Hydrolagus
ooiliei
SI
SI
SI
SF0
SW
92.9
95.5
13.9
16.4
61.5
10.2
25.4
48.1
30.3
510
SW
Kalacostraca: Eucarida
Oecapoda
Carl dea
Crannonidae
ñn;on atyliroatria
30.0
26.4
18.8
Brachyura
Brachyura megalops
Cancridae
murmjiater
20.0
1.0
0.1
nep mzjivLer meutopa
11.1
0.1
11.1
0.1
.0.1
100.0
96.5
1.1
1.6
05 59.1
13.8
106
61.5
1.3
2.9
4.5
0.4
0.5
7.7
1.4
5.4
45.5
8.2
8.6
7.7
3.1
1.0
30.8
2.3
8.1
23.1
21.8
6.1
3.7
Ma.Ildae
Echinodermata
Oendrasterldae
Denhaatcr exoentr'(oua
Ophiuroldea
10.0
5.5
5.3
30.0
2.8
6.2
PriapulIda
Osteichthyes
22.2
22.1
14.8
11.1
0.1
3.1
11.1
6.2
0.3
46.2
Auaodytldae
Aieiody tc
h.exaptvua
Gad idae
Microgadua proximua
Scorpaentdae
Sebuata op.
Agonidae
Bothidae
Cithaichthya atjrnaeua
10.0
10.6
10.8
10.0
10.6
10.8
33.3
0.9
3.9
7.1
0.6
3.7
13.6
1.5
1.6
Pleuronectidae
Parophrys vetuiuo
Unidentified materIal
5.5
2.3
23.4
8.7
9.0
11.6
Appendix III.
Summary of food habits data collected for Psettichthys
melanostictus, sand sole; Citharichthys stigmaeus,
speckled sanddab; Microgadus yroximus, Pacific tomcod;
Allosmerus elongatus, whitebait smelt; and Spirinchus
starksi, night smelt, collected at the 22 m station,
May 1979 (FO = frequency of occurrence, W = wetweight,
# = number).
Appendix III.
Alloamerua
Citharichthya
Miorogadua
Psettchthya
elongatua
meanotictu8 Bttqmaeua
proxinrua
SF0
SW
St SF0 SW St SF0 SW St SF0 SW
6.4
Polychaeta
1.5
-
Onuphidae
Nothria irideaüena
6.7
0.3
-
6.7
1.1
0.1
Spirinchus
Bt.arksi
SW
SF0
%H
St
26.5
2.9
2.9
10.4
0.1
<0.1
Copepoda
Ca Ian ldae
8.3
CalanuB ep.
1.2
1.3
I4alacostraca: Peracarida
,stdacea
Mysldae
Aoanthomysie dauiai
Aaanth,mysia macropaia
A<intho.nyaia eaulpta
A<<haeomyaia grebnitzkii
N'o.ejaia kadiaken8ia
Neo,eJeiB rayii
I'poneo.ny<ja wajiesi
5.0
2.2
2.5
3.2
<0.1
1.3
5.0
85.0
0.1
70.1
1.3
73.5
6.4
100.0
0.9
85.8
13.3
0.5
3.2
0.1
0.7
3.2
0.4
0.3
3.2
0.1
0.4
Atyl Idae
Atyluo .j<j.j
3.2
<0.1
0.3
tuipeliscidae
Ampeliaca nucroaephala
3.2
0.1
0.1
Cumacea
Diastylldae
66.7
40.0
22.3
5.8
33.3
6.7
26.7
13.3
6.7
6.3
2.3
5.0
12.3
10.7
0.1
6.7
<0.1
1.0
0.6
42.5
4.9
8.8
2.5
14.6
0.1
0.1
2.6
73.5
18.2
62.9
59.1
8.5
9.0
2.9
0.5
1.5
0.3
50.0
50.0
50.0
0.2
Ailiph poda
i
Gainuarldea
2.2
Haustoridae
Eohauatoriva aenailluu
6.7
7.5
4.9
Oedlcerotidae
:iynchelidiwn uhoeaw.ikeri
6. 7
<0. 1
0. 1
6.1
7.3
3.3
13.3
0.6
3.3
Phoeocephal ldae
boxipalua obt3de'
Mmdibulophoxuu
uniciroatiatua
Malacostraca; tucarida
Appendix III contd.
Psettichthya
melanoatiatus
SI
SF0
8W
Citharichthya
atigrnacue
Spirincus8
Alloamerua
Microgadua
proximua
elongatue
SF0
SW
SI
SF0
511
S
3.2
0.1
0.5
6.1
0,7
1,1
3.2
<0.1
0.3
13.3
18.1
14.4
1 .9
3.0
19.2
6.1
3.1
2.2
SF0
5(4
atarkai
SI
SF0
LW
SI
2.9
0,1
1.0
<0.1
6.9
0.1
5.1
8.8
3.5
3.3
2.9
1.3
0.6
2.9
3.2
2.9
Decapoda
Caridea bee
Crangonldae
C,.anjon vtyliroatria
Brachyura
Brachyura mega lops
Pinnotheridee
Piniiotherldae zoea
Plnnotherldae megalops
2.9
1.3 10.8
8.3
7.9
0.3 16.7
0.1
8.3
8.8
9.4
15.5
15.3
16.1
16.1
Anouiura
Porcel lanidae
Porcel lanidae zoea
Porcellanidae megalops
6./
<0.1
0.3
30.0
22.4
17.4
5.0
5.1
5.0
5.0
Paguridee unegalops
OsteichthYeS
Gadidae
Mi.uo.,;adua pOrUnuB
3.2
0.5
0.2
Cottidae
Artediva ap.
Pleuronecttdae
Iaopactta iaolepia
Cyclopterldae
Liparu.a ap.
UnidentIfied mater(aI
1.6
12.9
6.6
2.0
3.2
0./
0.1
18.2
6.7
1.8
1.6
20.0
2.2
Lb
6.7
3.9
4.9
3.2
0.5
0,2
18.2
16.1
0.0
6.0
aD
Appendix IV.
Summary of food habits collected for Parophrys
vetulus, English sole; Isopsetta isolepis, butter
sole; Platichthys stellatus, starry flounder; Raia
binoculata, big skate; and Hydrolagus colliei,
ratfish, collected at the 22 m station, May 1979
(FO = frequency of occurrence, W = wetweight, /1 =
number).
Appendix IV.
Polychaeta
Par'ophrya
Iaopaetta
vetulus
isolepi_s
Glycerldae
flyoera teflui8
Cigoinde azlniger<<
Giyoinde p iota
1.6
6.6
0.5
-
5.1
5.0
13.3
3.5
4.2
<0.1
0.2
510
sW
SI
60.0
0.8
-
10.0
0.2
5.0
5.0
3.7
6.1
20.0
46.7
0.2
0.3
3.0
<0.1
0.3
1.1
510
SW
I.uwbrner1dae
twnbrinerio sp.
Magelotildae
Mictona oaou lata
60.0
0.1
3.2
Nephtyldae
Nephty8 Sp.
66.7
0.5
3.2
20.0
<0.1
0.2
Hydrolagus
ooiliei
SI
SI
0.1
Raja binoaulata
night
SW
SW
60.0
day
510
510
Aphroditidae
Aphrodite Sp.
Clrratulldae
Chaetoaone aetoaa
PZatichthys
Bteiiatua
SI
10.0
0.2
0.8
20.0
0.1
0.1
510
SW
SI
510
SW
SI
Nereldae
Nereis sp.
6.7
0.3
Nothria iridesoena
13.3
0.1
0.1
0.1
Orbini dae
46.1
<0.1
3.8
13.3
0.4
0.2
6.7
<0.1
<0.1
20.0
6.7
40.0
0.1
0.1
0.1
0.5
<0.1
0.6
Onuphidae
5.0
2.3
0.7
Oweni tdae
b.Jenia collarie
Paraonldae
I'araonel la platybranohia
Phyflodocldae
4naitidea S.
Anai tidea given landia
teone Sp.
Sigalionldae
Iholoe minuta
7haianeeea epifloea
Splonldae
Polydora sp.
sp iophanea bombyx
6.7
<0.1
0.1
75.3
5.9
1.8
6.7
93.3
<0.1
0.1
12.3
iLl
0D
Appendix IV cont'd.
SF0
SW
Platiohthye
8telZatUB
Iaop8etta
ieolepis
Parophrya
vetulu8
SI
SF0
SW
SI
SF0
SW
Raja binoculata
night
SW
SI SF0
SW
Hydrolagua
oolliei
day
SI
SF0
3.5
3.5
Gastropoda
0.1
<0.1
SI
SF0
SW
SI
0.3
1.1
3.5
<0.1
1.1
Gastropoda egg case
Cyl ichnldae
Cyli<.hpu Sp.
6.1
0.5
0.6
53.0
0.7
0.8
46.1
26.1
3.5
0.5
0.3
13.3
6.7
0.6
6.1
13.3
0.1
0.8
0.1
0.4
6.1
13.3
0.1
0.1
0.4
0.4
01 ividae
Olit'eZZ
sp.
Pelecypoda
Pelecypoda siphon
1.1
20.0
10.0
5.0
1.4
5.0
5.0
5.1
5.0
2.5
0.1
6.1
1.4
0.4
0.9
kjcu1anIdae
Nucutana
loidju
minuta
sp.
Solenldae
Sili1uu 1'c<tuia
;iliqua sIphon
0.1
0.3
0.6
3.7
20.0
Tellinidee
Ma,o,e
Sp.
T'eliina
25.0
6.3
Sp.
0.2
25.3
12.5
6.4
2.6
2.0
3.5
0.5
0.8
Octopoda
Malacostraca:
Peracarida
Mys I dacea
Hysldae
Acanthornyaia daiai
.lcanthumyaia nlacropaia
Acmtha.rRJuia ucuipta
Ar.:ueo.,jai8 jrebnitzkii
Ncomyaia kadiakefleie
5.0
0.3
0.3
5.0
'0.1
0.1
46.7
6.7
0.4
0.4
<0.1
0.1
6.7
53.3
13.3
<0.1
1.4
<0.1
0.1
1.7
6.7
0.2
0.1
15.0
0.5
4.2
20.0
<0.1
1.3
93.0
6.4
0.3
6.6
15.0
5.0
10.0
0.2
1.2
0.3
2.2
0.9
2.2
10.0
10.0
10.0
<0.1
0.1
0.1
0.9
0.3
0.3
3.3
5.0
<0.1
0.4
0.2
15.0
20.0
0.6
2.0
20.0
0.1
Dies ty1 Idae
Anchiocolorus
Diaatytopsia dceuaoni
80.0
4.6
0.4
2.0
Laeipropldae
!h<mii..wIop8 sp.
60.0
2.3
Diatylia
sp.
sp.
26.7
3.5
'0,1
0,1
16.1
0.4
3.4
Neo,nuia rayii
Ctmiacea
1.6
44.9
0.6
0.1
3.6
6.9
1.5
2.6
0.1
0.2
3.5
0.2
6.4
8.8
0.8
6.3
.0.1
0.8
26./
1.4
9.4
6.3
6.3
0.1
0.1
2.0
2.0
Appendix IV cont'd.
Ioopstta
isolepia
SW S SF0 SW
SF0
6.7
Isopoda
<0.1
Raja binoculata
night
Platichthy8
arophrya
ateilatue
VetuluB
SE
SF0
SW
Rydrolagua
ooliiei
day
SE
SF0
SW
SE
3.4
0.1
0.2
SF0
SW
SF0
SW
SE
18.8
0.9
2.1
2.5
3.5
'0.1
2.5
2.5
20.0
1.0
3.4
SE
0.1
Idoteldae
Synjdotca bicuapida
Ida tea
5.0
0.8
0.4
ncanakii
Miphlpoda
Gauonaridea
13.3
0.1
0.4
35.0
1.0
8.1
30.0
12.4
11.3
10.0
0.1
0.1
3.5
<0.1
Atylidae
Atylue tridena
Ainpel scdae
Vnpeiiaca
sp.
4,eiiLJca JJa8ajaz.
Ae4ei isca macrocephala
13.3
66.7
93.3
1.3
1.3
1.2
3.0
8.8
10.5
10.0
15.0
0.2
0.9
3.0
5.0
0.1
0.1
1.2
13.8
0.8
Eusirdae
Rliaoot op is in flu ta
Gauinaridae
pus
6.7
6.7
<0.1
<0.1
0.1
0.1
Celk4Uatoriva 8CflOI 11U8
93.3
2.4
10.0
10.0
0.1
0.9
20.0
0.1
1.4
6.1
<0.1
1.1
0edcerotldae
13.3
86.7
0.5
3.7
5.0
0.2
0.3
20.0
0.2
0.3
6.1
0.1
1.1
5.0
<0.1
0.1
10.0
10.0
0.1
0.1
0.6
Mcja luzopta
Mclita sp.
lo?kJ irne
Haustoridae
;ynch ci idiwn ahoem.z&ari
13.3
0.2
1.5
<0.1
Photldae
6.7
33.3
20.0
<0.1
<0.1
<0.1
0.1
47.7
80.0
0.2
6.9
1.2
3.1
5.0
15.0
<0.1
2.5
0.2
1.8
80.0
80.0
80.0
0.2
0.2
0.6
1.7
1.4
10.0
<0.1
0.3
Monocutodea spin ipea
I'hotia sp.
Ihotia brevi pea
Phoxocephal I dae
Fariphalue obtucidens
0.1
0.5
0.2
Mandibu tophOXU8
uniosroa tra tuB
Rhepozynius epiatomus
Rheposynius vigi tecjua
Malacostraca:
Decapoda
Eucarida
2.4
0.8
3.4
0.1
0.2
Appendix IV cont'd.
IBopsetta
isoiepio
Parophrys
vetulus
SF0
SW
SI
SF0
SW
SI
13.3
0.1
5.0
3.8
0.1
Piatichthya
Btellatu8
SF0
SW
SI
Raja binoculata
night
SW
St SF0 SW
St
HydrolaguB
ooiliei
SW
SF0
day
SF0
SI
Caridea
Crangonidee
C?ngon 5p.
<0.1
Cznnqon a laakenais
Crangon fianiacoim
CranJOn atyZiroatra
Brachyura
Bracliyura megalops
20.0
0.6
0.4
6.1
'0.1
0.1
33.3
1.0
0.5
20.0
11.0
11.5
20.0
7.3
0.4
0.1
0.1
0.6
6.0
0.1
0.3
20.0
20.0
20.0
1.1
33.3
20.0
0.1
2.1
5.4
1.6
2.6
6.7
<0.1
.0.1
0.1
0.6
5.0
20.0
0.1
9.4
0.2
46.1
12.6
60.0
30.0
5.0
0.6
0.2
2.0
0.6
10.3
3.4
0.8
3.4
0.6
75.9
43.1
0.4
46.3
/2.4
44.0
34.5
13.3
7.3
2.7
62.1
32.1
14.2
62.0
29.1
18.8
13.3
66.7
5.6
25.5
36.2
2.9
0.1
0.6
3.5
0.1
0.2
13.3
2.9
5.8
11.2
1.0
2.6
13.8
3.8
4.1
13.3
2.7
8.9
27.6
3.9
1.4
23.3
2.1
2.4
13.3
5.9
5.3
6.9
0.5
0.8
6.7
4.6
1.5
0.1
Cancrldae
Cwicer gracilia
Cano.r magiater
Plnnotherdae
Pinnotheridae zoea
Plnnotheridae megalops
0.1
4.0
Anomura
Porcellanclidae
Porcellanldae zoea
Porcellanldae megalops
Pagurldae
Pagurldae zoea
Pagurldae inegalops
Echinoderinata
Dendrasterdae
14.3
9.3
21.4
21.0
30.0
6.4
2.1
80.0
8.4
3.6
45.0
18.7
14.9
40.0
44.7
22.6
Ophiurotdea
80.0
1./
1.5
30.0
4.8
4.3
10.0
<0.1
0.2
Nemertea
93.3
20.9
-
10.0
0.7
-
20.0
0./
10.0
6.3
2.7
Dendraater exoentricI4a
Ostel chthyes
Ajanodytidae
Anvnody
tea hexapterna
-
Gadldae
Miarogadun prOximuB
Cottldae
Appendix IV cont'd.
vetulua
SF0
SW
i8olepiB
Zä
SF0
SW
Raja binoazdlata
Piatiahthy8
Iaopaetta
Parophrya
BteliatU8
SI
SF0
SW
Bothidae
SI
day
SF0
44.8
Ci tharichthy8 atijimxeu8
4.2
ii
aolliei
SI
SF0
SW
SI
11.3
22.3
30.0
11.1
1.6
1.8
2.0
0.8
ue tu lua
19.9
fiydrolagua
SW
Pleuronectldae
Unidentified material
night
14.1
9.6
SF0
SW
SI
54.0
0
r'j
93
Appendix V.
Summary of food habits data collected for Eopsetta
jordani, petrale sole; Citharichthys sordidus, Pacific
sanddab; Raja binoculata, big skate; Raja kincaidii,
sandpaper skate; Raja rhina, longuose skate; and
phiodon elongatus, lingcod, collecte d at the 73 m
station, May 1979 (FO = frequency of Occurrence, W =
wetweight, # = number).
Appendix V.
Citharichthya
Eopsetta
jordani
SF0
SW
BOrdidUu
%ä
SF0
2.6
Polychaeta
3.5
Gastropoda
<0.1
SW
SI
0.1
-
06
Raja
binoo.ulata
Raja
Raja
kincaidii
SF0
SW
SI
33.3
0.1
26.7
SF0
SW
SI
Thecoso4na ta
tü,<.,ina sp.
38.5
10.8
12.2
2.6
2.7
0.6
2.6
0.1
0.3
Neogastropoda
OIIvldae
OiioelZa S.
Cephalopoda
Squid
6.9
0.3
1.3
3.5
0.4
0.8
Ostracoda
Copepoda
Calanldae
10.3
0.3
2.2
38.5
6.7
18.8
2.6
<0.1
0.8
5.2
<0.1
0.8
2.6
0.1
0.2
25.6
13.8
0.9
9.5
3.6
/./
1.1
1.0
2.6
0.2
0.8
2.6
0.2
1.0
2.6
0.2
1.5
2.6
<0.1
0.9
CaZapuda Sp.
Calanua plwn<hru8
Corycaeldae
Coi.yoaeua anglicua
Euchaet ldae
Paraeuhaeta SP.
Candaci Idae
Cunlaaia
sp.
Malacostraca: Peracarlda
I4ys idacea
I4ys ldae
Cacawomyeie vanoleeei
Aanthomyain nephropthalma
Cumacea
51.7
10.4
29.8
15.4
Diastyl ldae
VUJBtqti8
sp.
Lanipropldae
Herni1.mprops sp.
Isopoda
Sphaerumatldae
Aiophlpoda
100.0
0.3
Ophiodon
rhina
11.5
SF0
eiongatua
SW
SI
SF0
SW
SI
Appendix V cont'd.
Citharichthys
BordiduB
Eop8etta
jordani
SF0
SW
%
Gauiinarldea
LysIanassdae
!!ipponi.don sp.
3.5
0.1
0.4
llippomcdon dentiouluta
Oedicerotidae
Monooulode8 sp.
Photidae
Ihotia breV1.pe
3.5
0.1
SF0
SW
SI
2.6
0.5
2.3
2.6
2.6
1.2
0.1
1.0
0.2
2.6
O.1
0.2
2.6
0.2
0.2
15.4
SI
SF0
SW
33.3
0.1
7.7
33.3
3.2
7.7
OThiodon
elongatue
Raja
rhina
Raja
kinoaidii
Raja
binooulata
SF0
SW
SI
100.0
100.0
50.0
19.8
25.8
50.0
7.8
39.6
15.6
3.1
3.1
SF0
SW
SI
SF0
SW
SI
0.6
i'potoniodja S.
Hyper Idea
2.1
3.6
0. 1
1 .5
I,ut.h.,niuto j'uoifica
2.6
2.6
0.1
0.2
Phroslnldae
I'vOnno np.
2.6
1.6
1.5
20.5
16.2
12.3
8.0
2.4
1.8
2.6
0.8
0,3
5.2
2.6
0.5
Hyperldae
Il6pei.00he
meduacum
Malacostraca: Eucarida
Euphauslacea
Euphausl idae
'I'hya,znocsa Bpinij'eI'a
Decapoda
Crangon I dae
Crunjon sp.
Ci'ungon aiaukcnai8
51.1
14.1
Cranjon alba
CranIlon
I,.Ljon ntylizvatria
7.8
50.0
1.1
18.0
25.0
0.4
1.3
25.0
0.1
1.3
Anomura
Pajuridae
Brachyura
3.5
1.9
0.1
33.3
0,2
2,6
33.3
21.6
12.8
Cancridee
Ca,k,ur q)iutev
Plnnotheridae
'.0
tJI
50.0
4.1
4.2
Appendix V cont'd.
Eop8etta
jordani
SF0
SW
Cithariohtha
ordidua
S
Ctenophora
Salpa
Osteichthyes
SW
St
2.6
0.1
0.2
9.2
3.7
5.0
5.9
20.5
20.5
Citaetognatha
Insecta
SF0
3.5
0.3
0.4
11.2
5.8
1.8
2.6
0.7
Raja
binoculata
Raja
kincaidii
SF0
SW
St
33.3
35.4
33.3
33.3
35.7
2.2
33.3
2.8
2.6
33.3
0.1
2.2
33.3
0.2
2.2
SF0
SW
Raja
rhina
%
Ophiodon
eiongalus
SW
SF0
SF0
%W
St
75.0
46.3
41.6
75.0
75.0
15.0
50.0
1.2
9.7
25.0
4.2
10.1
25.0
4.2
19.1
25.0
20.8
14.3
25.0
25.0
25.4
20.8
6.3
St
1.7
Gad idae
2.6
MicrojaJus proxinnw
1.3
0.8
Anopiopomatidae
Anoplopoma fimiwia
Cottidae
/3adslinua aapreliaa
3.5
6.9
0.1
5.1
1.7
3.5
0.5
0.9
3.8
2.6
4.6
0.6
Agonidae
Ajonopais e,mnelane
Pleuronectjformes
20.1
12
/
7.8
Citharichthys aordidu
24.1
17.2
10.5
Pleuronectidae
Eopaetta jorwti
Giyptoccphaiva eachirsn
10.3
2.1
3.5
20.7
13.8
1.1
13.2
12.9
3.2
1.2
8.0
4.8
3.5
Bothidae
Isopsetta aolepia
Miorostomus paaificua
Unidentified material
10.8
6.8
6.3
16.0
8.9
4/.4
100.0
33.8
3.8
7.8
20.6
22.9
9.5
1.3
0.0
Appendix VI.
Summary of food habits data collected for Parophrys
vetulus, English sole; Microstomus pacificus, Dover
sole; Glyptocephalus zachirus, rex sole; Lepidopsetta
bilineata, rock sole; Isopsetta isolepis, butter sole;
and Pleuronichthys decurrens, curifin sole collected at
the 73 ni station, May 1979 (FO = frequency of occurrence,
W = wetweight, # = number).
Appendix VI.
MicroBtomus
Parophrya
vetujus
Sä
SF0
SW
25.1
-
37.5
15.6
2.9
<0.1
0.1
2.9
0.3
0.1
17.1
2.1
1.8
2.9
5.7
2.9
0.1
0.1
0.1
0.1,
0.1
40.0
20.0
1.6
1.0
6.7
1.8
2.9
57.1
<0.1
2.1
0.1
7.9
2.9
0.1
0.2
5.7
31.4
0.3
1.6
0.2
2.9
0.1
0.1
2.9
<0.1
0.1
5.7
<0.1
0.3
31.4
0.5
1.2
45.7
2.3
6.5
SF0
SW
71.4
Ampharettdae
Aphrodl tidae
Capt tellidae
P01 ychaeta
Ba pa nataL La ajneriaana
Vcc,rvnaa tuB gpuaiiø
Notamas tua lincu tuB
Chaetoptertdae
aioahaetopterua coa tarzan
Cirratul tOe
Chae tazone aa toaa
Glypt000phaluB
zacvru8
pacificnw
SI
-
SF0
SW
35.1
6.4
2.1
Li
SI
-
Lepidop8etta
i8oiep8
SF0
SW
St
IFO
SW
21.9
2.5
-
13.8
4.6
-
3.6
<0.1
3.5
0.2
1.4
3.0
17.2
3.5
3.4
<0.1
5.5
St
tFO
SW
St
50.0
2.1
-
100.0
97 9
0.2
0.2
0.3
8.3
Pleuronichthya
decurrena
IBopBetta
bilineata
3.6
1.7
<0.1
0.1
0.1
2.1
<0.1
<0.1
2.7
0.1
0.1
3.6
<0.1
0.7
18.9
2.1
1.6
3.6
3.6
<0.1
<0.1
0.6
0.9
3.5
2.3
0.7
2.1
0.2
0.2
2.1
'0.1
0.4
14.2
0.1
1.7
3.5
0.2
0.1
3.5
0.6
0.6
2.7
0.4
0.2
8.1
3.1
0.6
2.7
2.7
2.7
1.9
1.8
1.8
0.3
0.2
0.2
Glycerldae
Cigjcera t*<nuiu
Gon Id I dae
Glycinde ar.nigera
Ilestonidae
1.4
1.umbrtnerldae
tu,nbrineria sp.
Magelontdae
Magelona aaoulata
Maldanldae
4.2
0.2
0.5
Nephty I dae
Nephtys
Sp.
Nereldae
Cheilonereia cyoiurua
Nereia Sp.
Onuphidae
Nothria irideaoena
Ophel Idae
Ophelia sp.
2.9
<0.1
0.1
2'vaeisicz 9i9a8
17.1
12.5
1.9
OrbIni idae
11.4
0.3
0.6
7'rwiaia Jaetuda
3.6
1.8
0.6
100.0
Appendix VI cont'd.
Parophrys
etulus
Paraonide
Cirrophorue bparwhiatua
Pa,widalia asnevicana
SF0
SW
2.9
<0.1
0.1
5.7
5.7
SI
MicrostomuB
pacificus
510
SW
Glyptocephalus
achirua
SI
0.4
8.3
20.8
0.4
0.8
1.2
2.9
2.9
0.1
0.1
<0.1
0.1
0.2
4.2
<0.1
0.5
22.9
1.5
1.1
4.2
0.3
0.3
Polynoidae
2.9
0.1
0.1
4.2
0.1
0.5
Sigalionldae
7hal.meeea apinona
2.9
2.9
0.1
0.1
0.1
4.2
0.1
0.3
jteone sp.
Pllargidne
Ii La<gi8 berkeieyae
Spionidae
Polydora sp.
pio filicurnia
Spiophanea basnbyx
Syllidae
Terebellldae
liata sp.
Hiurdlned
11.4
<0.1
0.1
0.1
0.2
0.4
2.3
2.9
0.1
0.1
25.7
2.0
1.5
2.9
0.1
0.1
0.1
8.3
Colwnbellldae
Cylichnldae
ljchna
Sp.
Ohivldae
Oti'elia
Sp.
2.9
0.1
0.1
51.4
4.2
4.8
8.6
1.2
U.S
Pelecypoda
Nucal dae
,Yua/i tu41.e
Tell inidae
.11 ma nw,uloi den
4.5
2.7
2.7
2.7
2.7
<0.1
<0.1
0.9
0.2
<0.1
<0.1
SI
3.6
0.1
2.9
0.1
0.2
11.4
1.9
0.5
1
.8
16.7
6.3
3.6
4.2
1.4
0.2
4.2
0.1
0.4
2.1
<0.1
6.9
1.9
1.0
3.5
0.8
0.7
3.5
0.2
0.4
3.5
2.8
0.4
1.6
0.2
0.2
0.6
0.8
14.3
11.4
5.7
31.4
Gastropoda
ftit7!ia sp.
SI
0.2
0.8
Phyllodocidae
SW
Isop8etta
i8olepiS
SW
SF0
'0.1
0.4
Anartiden sp.
Anaitiden roeniandia
SF0
Lepidopeetta
bilineata
SF0
SW
SI
0.1
2.7
0.5
0.1
5.4
0.
a. 3
2.1
<0.1
0.3
24.3
2.0
2.3
2.7
'0.1
0.2
18.5
3.0
3.0
3.6
1.3
0.6
Pleuronichthya
decurrene
SI
SF0
SW
Appendix VI cont'd.
Microatomus
pacifiona
Parophrya
vetuZuB
Ostracoda
GZyptocephclus
zachirus
Lepidop8etta
bilineata
SW
SF0
SI
SF0
SW
SI
10.8
1.0
0.2
35.1
1.2
6.4
2.1
5.4
0.1
0.8
0.2
0.3
0.3
3.1
48.2
<0.1
1.1
0.4
9.5
13.2
1.7
13.5
0.3
1.0
3./
<0.1
2.9
8.6
0.6
0.6
0.2
0.5
0.3
0.8
3./
3.1
5.4
0.8
0.1
3.1
51.4
8.4
2.6
18.9
0.4
3.6
2.9
<0.1
0.1
29.7
2.7
6.4
0.1
3.9
2.7
0.2
27.0
SF0
51
SF0
SW
%
11.4
0.1
0.5
11.3
0.3
1.6
12.5
0.4
1.6
2.9
0.1
0.1
4.2
<0.1
0.5
5.1
1.0
17.1
11.4
511
I8opaetta
ieolepis
SF0
SW
Pleuroniohthya
deourrena
SI
510
SW
SI
Copeoda
Aeteidae
iJicu<
,1.<t.<,li:w
Ergasl 1 tdae
Ei<jaacitis sp.
3.5
0.1
0.4
0.1
3.5
0.3
0.7
'<0.1
3.8
0.4
3.5
0.1
0.3
25.9
0.2
4.4
13.8
1.6
4.2
11.1
1.2
1.0
17.2
7.1
7.0
0.5
4.1
1.2
1.0
3.7
0.2
0.4
3.5
0.1
0.2
0.9
3.5
18.5
0.2
2.2
20.7
1.9
8.1
2.7
16.2
81.1
5.4
<0.1
1.1
13.1
0.2
10.3
0.2
1.7
<0.1
157
3.5
31.0
0.2
11.8
0.8
0.6
21.6
0.6
2.0
Ilalacostraca - Peracarida
Nysidacea
Mysidae
Acanthornyuia nephropthat#s
Curnacea
Olastyl idae
Anc<w1ur
sp.
tL..<ty1in p.
Diaatytopeia da<<ni
Larnpropidae
II..,niljjnpropa sp.
Isopoda
Antlsirldae
ldotheldae
Synidctea sp.
29.2
1.1
5.7
4.2
0.4
0.5
33.4
5.5
8.3
Syriidotea biouepida
Sphaeroinatldae
2.9
0.1
.1
1/.1
0,6
1.1
2.9
62.9
0.2
0.4
4.8
0.3
0.9
8.0
8.3
1.2
0.7
11.4
1.6
1.2
12.5
1.0
2.6
0.1
Amphipoda
Ganaiaridea
fanpel lseidae
lrnpeIiaoa sp.
4npelia<'
aqiaaizi
4,,ç,elisaasr4croaaphaia
8iL'LC
11.1
29.2
1.9
5.5
<ron13
Eusiridae
RhacotPopi8 inJiata
1.2
66./
8.1
16.2
22.2
0.3
1.8
8.9
o
Appendix VI cont'd.
MicroatOmUB
Parophry
vetulu8
Glyptooephalu8
zachirus
pacificua
SF0
9W
%#
SF0
%W
2.9
0.1
0.1
4.2
0.1
bohau8tupij4a sp.
40.0
0.7
2.4
t.yslanassldae
5.7
14.3
2.9
0.3
0.7
0.8
1.6
1.2
0.1
8.3
0.6
SF0
SW
%
0.5
2.1
3.7
0.2
0.2
0.2
0.3
0.8
29.1
48.7
2.2
1.2
5.2
7.8
13.5
3.6
3.8
13.5
5.4
5.4
0.2
0.1
1.6
0.1
0.5
SF0
SW
Pleuroniohthy8
decurrena
Iaopsettcz
Lepidopøetta
bilineata
iaolepia
S
SF0
SW
%
3.5
3.5
0.1
0.1
0.8
0.7
3.5
0.1
0.1
SF0
G<ii.iiarldae
l.6<jluropuu 1oni.<nerua
Melita op.
Haustoridae
lljppom<c1on op.
llipp<miciam dentiauiata
lhppomudoi weconia
1.4
<0.1
0.4
3.7
<0.1
0.5
OediceroUdae
8.6
Monoculodea op.
5.7
Synohelidiamsp.
:;yncheiidiwn &iouukezi
5.7
0.2
<0.1
0.4
0.1
4.2
2.9
28.6
1.7
6.1
/0.8
19.6
0.4
2.5
17.2
2.2
6.0
1.1
0.3
39.5
4.6
0.6
21.6
4.2
4.2
2.7
0.2
0.1
6.9
4.4
6.0
4.2
0.1
0.3
35.1
4.0
0.6
1.0
1.1
5.3
4.6
6.9
40.5
3.5
0.5
0.2
3.5
0.1
0.2
3.5
0.1
0.1
24.1
14.3
3.6
3.5
3.5
1.8
Weutwoo.Ijlla c:aeuta
0.3
0.2
0.7
0.5
4.2
0.1
0.2
0.2
0.1
0.3
lsaeidae
/hotiu up.
iJe.'t.iB
bipea
Ipotju,elia
Op.
Phuoreiha1idae
Rhepoxyniuc sp.
kheg.<ryniuu epiata..mia
2.9
<0.1
31.4
2.0
0.3
17.1
13.1
2.2
0.9
Rhep.<xyniva vi(jit..jU8
boxiphalue obLuuoid<n<
2.9
Pleustidae
0.2
0.4
4.2
0.1
4.2
0.2
7.4
0.1
0.3
0.8
0.5
3.1
0.6
I.]
Podocerldae
!)uliohna
Malacostraca
op.
-
Fucarida
Decapoda
Carldea
5.4
<0.1
0.5
46.1
4.0
5.9
Crangon I dae
Czanon Op.
(,angon alaakenaia
2.9
0.6
0.1
48.0
11.4
11.1
4.2
9.1
1.4
tranyon atyiiiostria
Brachyura
pjnnotheridae
11.1
2.2
2.0
8.3
3.1
1.0
40.5
12.1
6.6
3.7
0.1
0.1
3.5
0.4
0.5
SW
SI
Appendix VI cont'd.
ParophrJ8
vetulus
SF0
SW
SI
Micros tornus
Gljptocephaius
pacifious
SF0
SW
sachi rue
SI
SF0
SW
Lepidopsetta
bilineata
SW
SF0
3.7
3.1
SW
SW
Pleuronichthya
decurrens
Isopsetta
iaolepie
SF0
SW
SI
31.0
12.2
9.9
6.9
0.5
2.4
3.5
2.8
-
IFO
SW
SI
Anomura
Call ianassidae
Ca11ia'aana oaliforniesaia
Upxjcbia sp.
Paguridae
Pagurid zoea
Pagurid megalops
Neunertea
2.9
8.6
<0.1
1.6
0.2
-
8.3
4.6
1.6
0.5
5.7
0.5
4.2
5./
8.3
0.4
54.2
21.6
-
20.8
2.9
-
2.7
4.8
0.5
8.1
4.2
3.1
0.6
2.5
0.4
0.4
-
Echinoderuiata
Dendrastertdae
tknIi'.zatn escentz'icun
Ophluroidea
Ascideacea
Spheroid pellets
8.6
0.6
0.2
45.7
1.6
2.6
8.8
0.3
0.6
11.1
2.4
-
Ellipsoid pellets
2.8
2.1
0.1
0.3
20./
2.2
5.0
8.1
0.6
0.6
31.0
14.4
16.5
2.1
0.9
-
3.5
0.4
0.4
3.5
3.3
0.4
Osteichthyes
Cottidae
Radulinus aaprellua
Pleuronectlforfiles
Bothidae
Citharicithya sordidua
2.7
1.9
0.1
Pleuronectidae
(flyptocephalun aaohirua
uippoglosooidea elae8odon
2.7
0.1
0.4
Iaopeetta iolcpi8
Unidentified material
23.3
10.8
21.7
1.4
0.4
2.4
25.9
4.2
3.5
3/.0
24.2
10.7
3.7
1.2
0.3
59.3
24.8
18.9
3.3
3.7
0.0
0