HMSC
SH
373.2
'
s19
.U5
\
071
1976/
1977
OREGO
t45
ar/I
BAY CLAFI OISTRIBUTIOi, ABUi.!DAICE, PLAi'!TIG SITES Aill) EFFECTS OF HARVEST
/
AthIUAL REPORT
July 1, 1976 to September 30, 1977
by
Thomas F. Gaumer
Oregon Department of Fish and Uildlife
4ational harine Fisheries Service
dational Oceanic and Atmospheric Administration
United States Department of Commerce
Commercial Fisheries Research and Development Act
Project dumber 1-122-R Segment 1
Contract dumber 04-6-206-44038
July, 1977
COP !TETS
Page
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CLAiDISTRIBUT1U.LSTUJIES
iethods
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Location of Suitable Intertidal and Subtidal
Results and Discussion .
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Tillanookt3ay . . . . . ..... . . .
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Clam Planting Sites
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etartsBay
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ASSESSHEiT OF CLAJ PLATIG SITES
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Population Estiiates
Yaina3ay
Tillanook Bay
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Coos Bay
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ethods
Results
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iative Littleneck Clais
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LITERATURE CITED
APPEiDIX 1
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Results and Discussion
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'ethods
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JHI4LE COVE ia3iLUuE
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butter Cams
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ianilaLittleneckClams
Yaguina 3a.y
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LiI30RATORYCLA-IFIELDSTUDIES
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Results and Discussion
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COERCIMLi3AYCLPuIFISHERY
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SURVEYS OF POTEdTIML COu4ERCIAL CLMfi BEDS
i8ethods . . . . . . . . . . . . . . .
Population Estimates . . . . . . .
Yguina ay . . . . . . . . . .
Tillamook Bay
Results and Discussion
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Results and Discussion
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Figures
Figure Ho.
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Page No.
Clam Survey Transect Lines and Sample Stations,
Distribution of Claus in Tillamook Bay . . . .
Distribution of Clams in Tillarnook Bay
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Tillamook
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Substrate Haterial in Tillamook Bay . . . .
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Substrate iiaterial in Tillamook day .
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Substrate iiaterial in Tillamook Bay . .
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Eelgrass Beus in Tillamook Bay . . . . . . . .
Clam Survey Transect Lines and Sample Stations,
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etarts Bay .
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UistributionofC1amsinetartsj3ay
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Distribution of Clams in etarts Bay . . . . . . . . . . . . . . .
Substrate iiaterial in detarts Bay . . . . . . . . . . . . . .
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Substrate ;gatrj1 in Hetarts bay . . . . . . . . . . . . . . a
Eelgrass Beds in etarts Bay . . . . . . . . . . . . . . . . . . .
Length Frequency of Gaper Clams (1976 Year Class) from Ore-Aqua
Raceway Saiple, Yaquina Bay, 1976 . . . . . . . . . . . . . . . .
Length Frequency of Cockle and Butter Clams (1976 Year Class) from
Ore-Aqua kaceway Sample, Yaquina Bay, 1976-77 . . . . . . . . . .
Age Composition of Gaper Clams, Areas 2 and 3, Yaquina Bay, 1975-76
Age Composition of Subtidal Clams in Area 3 of Yaquina Bay, 1976 ,
Age Composition of Subtidal Clams in Garibaldi Area of
Tillamook day, 1976 . . . . . . . . . . . . . .
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Length Frequency of Subtidal Clams in Garibaldi Area of
21
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Location of Subtidal Experimental Commercial Clam Plots, Yaquina Bay.
Location of Subtidal Commercial Clam Plots, Coos Bay, 1976 . . . .
Age Composition of Gaper Clams in Commercial Clam Plots, Area 2 of
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Length Frequency of Subtidal Clams in Commercial Clam Plots,
Vaquina Bay, 1976 . . . . . . . . .
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Age Composition of Commercially Harvested Gaper Clams, Coos Bay, 1976 .
Length Frequency of Commercially Harvested Gaper Clams,
Coos Bay, 1976 . . . . .
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Growth Curve of dutter Clams Planted on the Breakwater, Yaquina Bay
(Vertical Lines Indicate Range in mm), 1976 . . . .
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Growth Curve of native Littleneck Clams Planted in Artificial Substrate
Plot, Yaquina day (Vertical Lines Indicate Range in mm), 1976 . . . .
Growth Curve of Uhale Cove Abalone (Vertical Line Indicates Range),
16
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Tillariook Bay, 1976
Yaquina Bay, 176
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1976
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Tables
Table Ho.
1
Population Estimates of Subtidal Clams in Areas 2 and 3,
Yaquina Bay, 1975-76 . . . . . . . . . . . . . *
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Summary of Estimated iumbers of Subtidal Clams in Garibaldi Area
"1-C" of Iillamook Bay, 1976
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Growth and Survival of Butter Clams Planted on the Yaquina Bay
Breakwater, 19751/
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iEGth4 diY CLii dISTRIbUTIth, iUDACE, PLAI1TLG SITES AO EFFECTS OF HPJWEST
1STRACT
iJe continued our studies of the distribution of bay clams in Oregon's estuaries.
iaps shosing survey areas, distribution of clanis, substrate type and vegetation type
are presented.
4
Population estimates, age and size of clams were calculated for two areas of
Yaquina day and for one area in Tillamook bay. Gaper clams were the principal species
found in each bay. In Yaquina ay our surveys revealed a strong 1976 year class for
gaper clais in June but by October, this age group was practically absent. The 1975
year class gapers remained the predominant age group in each bay.
Five permits were issued for the commercial harvest of subti dal ci arns.
o clams
were harvested froii the two permit areas in Yaquina Bay. Only one of three permit
holders in Coos day harvested clams, taking 46,467 pounds (21.1 m.t.) of gaper clams
during dovember and December, 197i.
We continued to monitor growth of laboratory-produced clams planted in iletarts
and Yaquina bays.
Population estimates showed 267 (5.2%) of the abalone planted in Whale Cove in
They averaged 14 mm in size, an increase of 16.7 mm since 1975,
1967 still survive.
We salvaged over 73,000 1976-year class gaper clams from Ore-Aqu&s salmon
production raceways and released them on Idaho Flat of Yaquina Bay. An attempt will
be made to evaluate the released clams' contribution to the natural stocks.
LlTROOUCTIOW
The objectives of this study were: (1) to continue mapping the distribution of
the bay clams in Uregon1s estuaries; (2) to locate and assess intertidal clam
planting sites; (3) to evaluate th effects of mechanical harvest on subtidal clam
populations and habitat;
and to monitor growth of laboratory reared clams released
in detarts and Yaquina bays. In addition we continued to monitor the growth and
survival of abalone planted in Whale Cove.
CLAh DISTRL3UTIOd STUDIES
During the year we continued our clam surveys on Tillamook and detarts estuaries.
Clam distribution surveys were completed in Yaquina Bay in 1973 (Lukas and Gaumer,
1974), Alsea Bay in 1974 (Gaumer and Lukas, 1975), and Hestucca and Siletz bays in
1975 (Gaumer and Walstead, 1976).
ethods
Location of Suitable Intertidal and Subtidal Clam Planting Sites
We continued to evaluate the distribution of intertidal and subtidal clams using
tecnniques developed during the 1973 fiscal year (Osis and Gaumer, 1973).
Criteria
used for determining areas having potential for planting native or exotic species of
0
S
-2-
clams included the presence of native species of clams (both intertidal and subtidal),
substrate type, and water depth. Subtidal surveys started at the mouths of each
estuary and extended up-bay until we were confident all major clam beds had been
examined.
Location of clam beds on intertidal tideflats was accomplished by establishing
transect lines across each of the tideflats, Observations made at established stations
along the transect line included species of clams in the area, relative density of
each species of clam, substrate type and vegetation type. Similar observations were
made subtidally by Agency scuba divers.
Results arid Discussion
Tillaniook
S
S
S
Bay
tie continued the intertidal clam distribution surveys on Tillamook Bay.
We made
478 observations along 105,830 feet (32,257 in) of transect line. Figure 1 shows all
observations made to date including those in 1976.
Of the recreationally or commercially important clam species, gapers (Tresus
and cockles (Clinocardiurn nuttalUi) were the principal species observed in the
lower bay while the softshell (Za arenaria) was the most prevalent clam species in
the upper bay. The distribution 0f gaper, cockle, butter (Saridomus giganteus),
native littleneck (venerupis staminea), softshell, bentnose (Macorna nasuta), Baltic
(Macama baithica), sand (Macama secta), irus (Macama irus) and California softshell
(cryptomya califoxanica) clams were charted (Figures 2 and 3). Ghost shrimp
(callianassa californiensis) and mud shrimp (upogebia pugettensis) were also scattered
over much of the tideflat areas examined.
capac)
iuch of the substrate in the Garibaldi area of Tillamook Bay consisted of gravel
and rock with some shell and sand. This area supports some 0f the heaviest concentrations of intertidal and subtidal bay clams in Oregon's estuaries. The mid-and
up-bay portions of the estuary were primarily of mud or mud-sand conbinations (Figures
4, 5, 6 and 7).
Vegetation, primarily eelgrass (zostera marina), covered much 0f the tideflats
(Figure 8).
,etarts Bay
We continued the intertidal surveys on tietarts Bay. The subtidal surveys were
completed in 1975. The 1976 intertidal surveys included 270 observations along
64,730 feet (19,730 m) of transect line.
Figure 9 shows all the transects covered
to date.
Cockle, butter, native littleneck, softshell, anula littleneck (venerupis
philippinariwn), beritnose, Baltic, California softshell, irus, bodega tellen (Tellina
bodegensie) and piddock (zirfaea pilsbryi), clams were widely scattered over much
of the bay (Figure 10 and 11). iud and ghost shrimp were widely distributed over
most of the tideflats.
1any of the tideflats surveyed in 1976 consisted of a combination of sand and mud.
The down-bay channel areas were primarily of rock, gravel and sand (Figure 12) whereas
the up-bay channels were covered with sand and shell sediments (Figure 13).
0
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Eelgrass was the principal species of vegetation covering the tideflats
(Figure 14).
n
ASSESSEdT OF CLAu PLMTH4G SITES
Efforts were made during the year to assess the feasibility of enhancing natural
populations of clams. Areas selected for enhancement were those that historically
have produced large numbers of clams, but have shown a gradual decline in abundance.
1e
th ods
In July 1976, Ore-Aqua, which has a private salmon rearing hatchery on Yaquina
3ay, informed us that their raceways contained large numbers of juvenile gaper, cockle
and butter clams.
In the normal routine cleaning of these raceways, most of the clams
are lost when dumped into a waste water lagoon.
To reduce the loss of these clams,
ODFU and Ore-Aqua personnel, using a suction pump, initiated a program of salvaging
the clams as the ponds were cleaned. Clams were salvaged in July, August, September
and January. The gapers collected in July were placed in a 50x50-foot (15.2x15.2 m)
plot at a mean density of 12/sq. ft. on Idaho Flat of Yaquina Bay.
The test plot had
a sand-mud substrate and was nearly covered with eelgrass.
Tidal height was
approximately 0.0. The clams planted in August, September and January were broadcast
over a more general area adjacent to the July planting site.
Results and Discussion
Approximately 73,700 1976-year class gaper clams were planted on Idaho Flat;
30,000 in July, 25,000 in August and 13,700 in September.
In addition, several
thousand 1976-year class cockle and butter clams were planted in January.
Figure 15 shows the length frequency of gaper clams planted each month.
ilean
size in July was 15.7 mm; August, 20.9 mm; and September, 23.8 mm. Length frequency
for cockle and butter clams is shown in Figure 16.
SURVEY OF POTEi!TIAL CUflHERCIAL CLAH BEDS
Ue continued our assessment of subtidal clam stocks in Tillamook and Yaquina bays
using a hydraulic dredge and techniques previously described (Gaumer and Lukas, 1975).
Data collected included abundance of clams by species, size and age composition,
bottom composition, vegetation type and water depth.
iethods
Pol ati on Es ti mates
Yaquina Bay. Two Yaquina 3ay clam beds, surveyed in 1975, were resurveyed in
1976 to collect information on recruitment and natural mortality.
Both areas (2 and 3)
were determined in 1975 to have a high potential for supporting a commercial clam
fishery.
Twenty-four dredge samples were collected from the 18.4 acre (7.4 ha) site
in area 2 while 0 samples were taken from the 35.6 acre (14.4 ha) site in area 3.
S
-4-
'
bed.
Tillamook bay. lie completed our surveys of the Flobsonville Point channel clam
Forty-seven dredge samples were taken from the 34.4 acre (13.9 ha) area.
Results and Discussion
Population Estimates
Yaquina Bay.
From our dredged samples we estimated that 46.7 million clams
inhabited area 2 and 121.3 million clams populated area 3 (Table 1). The area 2 figure
represents a decrease of 5.8 million clams from 1975 whereas the area 3 population
had an increase of 98.1 million clams. aiost of the increase in area 3 reflects the
predominance of gaper clams of the 1976 year class.
This sample was taken in June.
The area 2 samples were taken in uctober and contained few 1976 year class gapers,
suggesting a massive mortality between Ju'ie and October. Figure 17 shows the age
conTposition of yaper clams from each area. Areas 2 and 3 were adjacent to each other.
Age composition data for gaper, cockle, littleneck and butter clams from area 3 are
shown in Figure i. Each species is represented by an exceptionally strong single
year class; 1976 for the gaper clam and 1976 for the cockle, littleneck and butter
clam.
Table 1.
Population Estimates of Subtidal Clams in Areas 2 and 3,
Yaquina bay, 1975-76.
11
Species
Gaper
Cockle
native littleneck
butter
1L2
36,300,000
183,000
366,000
416,300
13,533,000
1,700,000
i(
iL'
25,566,000
17,000
217,000
334,000
20,566,000
13,608,000
462,000
166,000
567,000
7,854,000
U
0
0
273,000
Bentnose
0
0
163,000
Jack knife
Cryptomya
Sand
0
0
0
0
0
0
42,000
0
0
0
21,000
21,000
52,498,000
46,700,000
23,142,000
121,254,000
Irus
Piddock
Bodega tellen
0
77
Total
0
39,203,000
441,000
3,297,000
3,822,000
23,394,000
42,000
693,000
315,000
Tillamook 6ay
We estimated that 18.7 million clams inhabited the survey area (Table 2). Of
this total, 4.3 million were gapers, 3.7 million were cockles and 2.6 million were
native littlenecks.
Figure 1 shows the age composition of gaper, cockle, littleneck and butter clams.
Fifty-eight percent of the gaper clams were of the 1975 year class.
!o 1969 or 1971
year class gapers were observed, adding to data indicating sporadic nature of survival
of gaper set. The 1974 year class was strongest for cockle and littleneck clams
while the 1966 year class was the main age group of butter clams.
-
The length distribution for dredged clams is shown in Figure 20. ean size of
gaper, cockle, littleneck and butter clams was 65.0, 59.2, 36.5 and 68.8 nun,
respectively.
Table 2.
Suniiiary of Estimated 1!umbers of Subtidal Clams in
Garibaldi Area U1_C of Tillamook Bay, 1976
Species
iiumber
Gaper
4,324,400
3,797,900
2,601,000
Cockle
dative littleneck
Butter
Irus clam
Softshell
731,300
6,366,900
345,700
Total
1,717,700
COiiIIERCI AL BAY CLAI F I SHERY
Five corniaercial clam diggers received special permits to mechanically harvest
Two permits were issued for Yaquina Bay and three for
Coos bay. Each permittee in Yaquina Bay was assigned a 7.3 acre (3 ha) plot (Figure 21).
Two of the permits in Coos Bay covered 24 acres (9.7 ha) each whereas the third permit
restricted the harvest only to the main channel area downstream from Empire (Figure 22),
clams subtidally in 1976.
1ethods
n
Yaguina Bay
Two adjacent areas were selected in Yaquina Bay for an evaluation of two different
types of mechanical clam harvesting techniques. Of primary concern was the effect
of these harvesting techniques on the clam resource and habitat. Each test area was
located in area 2, immediately upstream of the U.S. highway 101 bridge.
Within eaci permit area, sub-units of 2.1 acres (0.3 ha) were delineated with
a steel cable stretched around their perimeters. Each of these sub-units was further
subdivided into lOOxlOO-feet (30.5x30.5 m) sub-sections. Five dredge samples were
taken by ODFii from each of four sub-sections to provide baseline data on species
composition and age structure (samples were dredged from two sub-sections in each subunit). All dredged clams were measured, weighed and aged.
Commercial clam harvesting perciits were issued for each area. One permit holder
was required to harvest clams using a high pressure water jet and scuba while the
other was permitted to use a 6-inch (15.2 cm) suction pump and scuba. Each permittee
was restricted to a specific sub-section within his permit area until Department
biologists approved moving to another sub-section. Each perrnittee was allowed to
harvest 200,000 pounds (90.7 metric tons) of gaper clams and was required to file
monthly harvest reports listing areas worked, numbers and pounds harvested by species,
and diving time. Ue were to periodically sample the catch to obtain age and size
composition data.
S
Coos Bay
The two clam harvesters in the 24 acre (9.7 ha) units were required to use a
high pressure jet of water and scuba to remove clams. iio restrictions were placed
on where they could take clams within their respective units.
Each fisherman was
allowed to harvest 100,000 pounds (45.4 m.t.) of clams.
io restrictions were placed
on species although the gaper clam was the primary target species in these areas.
The perniittee for the channel area was allowed to use a boat-towed hydraulic
dredge to harvest clams.
io restrictions were placed on species or numbers taken
although the cockle clam was the primary species of interest.
Each Coos Bay fisherman
was required to submit the same type of information as required for the Yaquina Bay
harvesters.
Results and Discussion
Yaquina day
Figure 23 shows the age composition of gaper clams in each of the four sub-sections,
based on our samples.
The 19Th year class was the principal age group in each area.
Large numbers of the 1970 year class also were present, especially in sub-sections K-i
and 6-7.
do 1974 year class clams were removed from the four areas.
Figure 24 shows the length frequency distribution of subtidal gaper clams in the
four sample areas.
The clams ranged in mean size from 59.0
in area K-3 to U6.1 mm
in area G-7.
m
deither of the permittees from Yaquina Bay produced clams in 1976.
Both individuals
were privately employed in other non-related full time occupations and were unable to
find time to initiate a fishery. As a result, we were unable to collect the data
necessary to evaluate the effects of the water jet and hydraulic suction pump on the
clam resources or habitat.
Coos Bay
Only one permit holder reported a harvest of clams from Coos Bay. The fishery
produced 4i,467 pounds (21.1 m.t.) of gaper clams during dovember and December. Using
a single diver, this fishery produced an average of 213 pounds (96.6 kg) per hour or
1,223 pounds (554.7 kg) per day.
Age composition of the harvested gaper clams is shown in Figure 25. flean age of
the gapers was 7.8 years. As the harvest from the same area in 1975 showed, the
1966 year class was the prinicpal age harvested. Length frequency distribution of the
commercially harvested clams is shown in Figure 26.
dean size of the clams was 133.2 mm.
LABORATORY CLAd FIELD STUDIES
tie phased out our laboratory clam studies in 1975. Since then we have monitored
the growth of clams planted in detarts and Yaquina bays.
ethods
Our studies on detarts Bay were limited to measuring the growth characteristics
of Manila littleneck clams selected for their fast growing ability vs. normal growing
I
-7-
and Lukas, 1975).
area was also measured.
clams (Gaumer
Growth of clams in a screened enclosure vs. unscreened
Our Yaquina Bay studies included an evaluation of the growth and survival of
butter and native littleneck clams planted in 1970 in a natural substrate vs. an
artificial substrate experiment (Lukas, 1972).
Results and Discussion
iIetarts Bay
ilanila Littleneck Clams. Nanila littleneck clams, spawned in August 1974 from fast
growing parent stock grew 11.4 mm since Nay 1975 and averaged 22.4 mm in length whereas
progeny from the "normal" clams grew 10.6 mm and averaged 21.0 mm.
tsanila clams planted in the screened test plot averaged 27.7 mm. Clams planted in
an unscreeneu test plot adjacent to an eelgrass bed and at a slightly lower elevation
were 33.5 mm in average length. Clams in all three releases averaged 13.1 mm when
planted.
Yaquina day
Butter Clams. From a test plot in natural substrate we screened a three-squarefoot (2.5 m2) section that had never been sampled. This eliminated any adverse affects
due to handling. Nean shell length of recovered clams increased 6.3 mm, to 60.0 mm
(Table 3). The reason for observed differences in survival of butter clams during the
five sampling periods is unknown. Either the clams were not randomly distributed
when planted or there were subtle environmental differences from one end of the plot
to the other which affected survival.
Table 3.
Growth and Survival of butter Clams Planted on the
Yaquina 3ay Breakwater, 19761/
Date Sampled
7-13-72
7-30-73
7-19-74
7-9-75
7-27-76
1/
ilean Shell
Percentage
Age of Clams
Length(nini)
Survival
i4onths Tn
(flonths)
Plot
44.5
57.0
68.0
80.0
92.0
22.0
34.5
46.0
53.0
70.0
37.0
46.7
43.4
53.7
60.0
31.7
46.7
59.2
65.0
68.3
Butter clams averaged 20 mm when planted.
Figure 27 shows that growth of butter clams in the natural substrate lagged behind
a comparable group planted in an artificial substrate plot located about 100 yards
(91.4 m) away although the average length of butter clams in the artificial substrate
plot increased only 1.0 mm in the past year as compared to an increase of 6.3 nun in
the natural substrate.
Jative Littleneck Clams. Small numbers of littleneck clams remaining in our test
plot necessitated measuring all clams to obtain growth and survival data. This has
S
I
been done since 1972; consequently, growth of the clans may have been retarded due to
handling.
In 1976 the clams averaged 37.0 mm, a decrease of 5.2 mm since 1975
(Figure 23).
fl
tJHALE COVE ABALOiE
In 1967, 5,500 juvenile red abalone (Halioti8 rufescene) were purchased from a
commercial hatchery in California and placed in Whale Cove, Oregon.
Since 1972 we
have annually counted and tagged the abalone to monitor growth and survival.
1 iethods
The yearly sampling of red abalone planted in Whale Cove was conducted in July 1976.
Only the rocky intertidal area was searched; tidal height was -1.4 feet (-0.4 rn).
Results and Discussion
Twenty-nine abalone, having an average shell length of 154 mm with a range of
120-188 mm, were captured (Figure 29). Of the 10 previously tagged abalone recovered,
12 had been tagged in 1973, three in 1974 and three in 1975.
The mean annual increase
in length since 1975 was 10.0 mm with a range of 5-18 mm. Eleven abalone tagged in
1973 and not recovered in 1975 were recaptured in 1076. These animals had grown an
average of 36.5 nu with a range of 15-53 mm.
Mark recovery data showed that 237 (5.2%) of the original 5,500 juvenile red
abalone planted in 1967 still survive in Whale Cove.
io juvenile abalone were observed
from natural spawning, although adult abalone with mature gonads have been seen in the
cove since 1972.
SU1ARY
Since 1973 we have surveyed along 793,5G0 feet of intertidal and 483,600 feet of
subtidal transect line to determine the distribution of bay clams. Observations on
species of clams, relative density, bottom type, and vegetation type were made at
7,998 sample stations.
tie salvaged approximately 73,700 1976 year class gaper clams from the raceways
of Ore-Aqua salmon production facilities and released them on Idaho Flat of Yaquina
Bay.
Several thousand cockle and butter clams were also planted on the flat. Additional clam enhancement programs will be attempted as clams become available.
Three subtidal clam beds were extensively surveyed during the year. Two of the
beds were in Yaquina Bay and had also been surveyed in 1975. The third bed was in
Tillamook Bay. The clam beds in Yaquina Bay contained 75.6 million clams in 1975 and
168.0 million clams in 1976.
The increase was the result of a strong 1976 year class
of gaper clams.
Observations since these surveys have revealed a nearly 100% loss
of the 1976 year class gaper clams.
The clam bed in Tillamook Bay contained an
estimated 18.7 million clams, The Tillamook survey was done in April, which precluded
the 1976 year class gaper clams from showing in the samples.
Fifty-eight percent of
the gaper clams was of the 1975 year class.
P
w
-9-
Five commercial clam diggers received special harvesting permits to take subtidal
clams in 1976. Two of the permIts were for Yaqulna Bay and three were for Coos Bay.
Of the five, only one CoOs Bayfishernan harvested clams. He reported a take of 46,467
pounds (21.1 m.t.) of gaper clams during Hevember and December. This fisherman averaged
213 pounds (96.6 kg) per hour or 1,223 pounds (554.7 kg) per day. ilean age of the
clams harvested was 7.8 years. The 1966 year class was the principal age group taken.
The clams averaged 133.2 mm in shell length.
n
Of the Manila littleneck clams planted in F4etarts Bay, clams spawned from fastgrowing brood stock grew slightly faster than those from "normaV' clams.
Butter clams
planted in an artificial substrate plot in Yaquina Bay grew 1.0 mm while those planted
in a natural substrate grew 6.3 run. Total growth, after 92 months, remained better for
clams planted in the artificial substrate plot. Average shell length of native littleneck clams planted in Yaquina bay was 5.2 mm smaller than in 1975, indicating a
differential natural or handling mortality of the larger sized clams. All clams in
this test plot are removed and measured each year, then replanted.
Red abalone planted as juveniles in 1967 in Whale Cove averaged 154 mm, an increase
of 16.7 mm since 1975.
kark recovery data showed 287 (5.2%) of the original 5,500
still survive.
ACKi4OWLE DGHEHTS
I wish to thank Bruce Haistead, Dennis Wise, and Gerald Lukas of the Oregon
Department of Fish and Wildlife for their assistance in the study.
I also wish to thank Connie Warehouse, illustrator for the Oregon State University
Sea Grant College Program, for the many hours she expended preparing the resource maps
for this report.
LITERATURE CITED
Gaumer, Thomas F. and Bruce G. Halstead,
1976.
Hethods of Supplementing Clam and
Abalone Production.
Corn, Fish. Res. and Devel. Act. July 1, 1975 to June 30,
1976.
Ore. Oept. of Fish and Wildlife Proc. Rept. 65 pp.
Gaumer, Thomas F. and Gerald Lukas.
1975.
Wethods of Supplementing Clam and Abalone
Production.
Cor. Fish. Res. and Devel. Act. July 1, 1974 to June 30, 1975.
Fish Corn, of Ore. Proc. Rept.
pp.
Lukas, Gerald. 1972. Clam-Abalone Spawning and Rearing. Comm. Fish. Res. and Devel.
Act.
July 1, 1971 to June 30, 1972. Fish Comm. of Ore. Proc. Rept. 16 pp.
Lukas, Gerald and Thomas F. Gaumer.
1974.
Clam-Abalone Stock Supplementation
Feasibility Study. Corn. Fish. Res. and Devel. Act. July 1, 1973 to June 30,
1974.
Fish Corn, of Ore. Proc. Rept. 20 pp.
Osis, Laimons and Thomas F. Gaumer.
1973.
Estuary Resource Survey, Subtitle: Clam
Inventory Techniques Study. Corn. Fish. Res. and Devel. Act.
Completion Rept.
July 1, 1971 to June 3u, 1973. Fish Comm. of Ore. Proc. Rept. 11 pp.
-'U-
0
fl
IPPEI4JIX
1
(Figures 1 through 29)
n
S
S
S
.
S
S
.
-11-
BALt I
U
0
LI
U
II
II
I'
CAcE M41
1iIIavcykay
ampIin8 -r441G+ hues
IIttIIIJlflIII
1000
0
/000
200o
s000
FIGURE 1.
0o0
3O0o FEET
CLAM SURVEY TRANSECT LINES AND SAMPLE STATIONS, TILLPfl)OK BAY
S
.
V
-12-
GLDI
:s
sS
SSs
SS
sss
flg
SSS$
S
b
sSs
Ss
S
S S1
g
n
bg
cgg
bC
ccrJb;3SS
c
/1 c
)C(/
z
\(
C)
Si
Cgcc\
'-_
c s\
(
'
L)
0
II g
S
.
C
I-I-
L)
-:c-'5 si(
ss\s
SSt\
I)
J"U
\J1
gfl
cccg
S CC
9gCgc
CCCC
SSCC9CC
SS,__SS
III:ii:i:i
C CCC CC
S
S
S,SS SS CC S
SC
s s S s c c S S s sg
SSSCCSSSSS
SC
s
5)
S
sb
S
\c
SSSS\
% SSSSflSSSS
t'- S SSSSsSs\\s ssJ
SSSSSSSSSSNS.t
S
\
SSSSSSS
19)
SSSSSS
'SSSS SSSSS
SSS SSSSSS
S
SSSSSSSS\S
(
SSSSSSSSSSS
SSSSSSSSSSS
b
/
J\l
Issss
S S\SSSS
\ 's
S
I)
$
'SSSsS s
s;s
S
SsSs S SSs
S
ss S
ssSss
SS SS$
S
S
scSssSssssssssss 5'.
ss s\ss
CAP MEARES
VA
mIIrook 'ey
cIak
N
popt4lahOPl pcAltKV1S
g
CinocardiLAp1 ruAftfljJ
(gaper davi)
(cockle cjaw
5xidofr'4us SiaifeMs
(buffer ck,rn')
b
Vererupi st
(viative l+fievxeckckw\)
Myc crevIaric
(5ofetl ckv)
TresM cg
i000
0
/000
000
3000
y000
$
.-000 FEET
FIGURE 2
DISTRIBUTION OF CLAMS IN TILLAIIJOK BAY
S
SS SS
S
S
S
S
-13-
V.
e
0
ej
eere
re
0
0
ri
r
i\1i
U-
U
e
eaaaa'Wa a
aaIeeeeeea
(
'-'V
'\
\.
eeeee
ee ee&feee
eeeeeeee
eeeeeaee
t
eee
e
aeaeaeae e
a
a1aea e e e e
eaea'eaeaeaee e e
aaeea eeeeaee
ajeee eeeee
,a eeae eee
-eee
ael
'a ee aea a ee\ee
r r r r
'eaeaa aa aaeaa
aa aaa aa'a
eaeaaaaaaae
t
aaa
a
r'r
a
a
aaa
'aa
aa
aaaa
aaa
e
r
ç
ae
aäa
aa
a aaa'eaa
Jaaa a a a\)
a
[
a
.
rr\
rrrrrrr
rrr r r a
eaa"ae
aaaaaaa
rras
r r r
rr
r
1
a
a a'
earaa
ra r
ra
aaa
\\r
a
r
ra
rar a a
a r
ar
a aaa aaa
ar
a/a
CAVE MEARES
Tillamook'Bay
c11ai poput'ltiOP% pafferris
cQI
(oeYtv\O5S c')
c6i4fr-'
a
(baHc cIcwv')
ba(Thicc
Mc,coc irws
(irtis cavi1)
(dckrn"1)
CryQny cavIc
1000
o
/000
2000
d
(CfsaF+5he clan')
3000
4000 5000 FEET
FIGURE 3i
DISTRIBUTION OF CLN1S IN TILLAI43OK BAY
a
ara
a
a
a
a
S
I
I
I
2
w
U
0
U
U
¶I1tV)1OOk 'Bty
-
substrate nia+eriais
sd
bedrock
I
.
/000
FIGURE 14,
0
SUBSTRATE MATERIAL IN TILLAMOOK BAY
/000
-
rock
2OOO
3000
I
a
.
.
o
-15-
\\
\
\
\
\\.
c\
\..
/
\
'':.
:
\
BAY CITY
lillamook Bay
N
subsfrcfe victeriaIs
sovici
riid
sieI
bed vock
grcveI
/000
.
0
b
rock.
/000
30
FIGURE 5
SUBSTRATE VIATERIAL IN TILLAMOOK BAY
.
0
.
.
0
-16-
FIGURE b.
SUBSTRATE MATERIAL IN TILLPI1OOK BAY
S
S
S
0
.
-17-
0
0
U
(J
Li
I
CAPE MEARES
1Thc4rYook 'Bcky
\I
s u slnite
ititeriaIs
scid
stieH
bedrock
-
grcveI
1000
.
0
rock
/000
2000
FIGURE 7.
3000 FEET
SUBSTRATE MATERIAL IN TILLAMJOK BAY
.
-18-
GAP-I BALD I
2
U
0
U
I1
U
b
TiJlaiookBy
eel grass desities
5ptY5
iodcra+e.
dense
/000
0
/000
a000
500o boo soco FEET
FIGURE 8.
EELGRASS BEDS IN TILLAMOOK BAY
S
S
S
*
S
*
-1 9-
TA5
I
j/
N
Ne+ar+6 &c4y
5antpIiPl5
/
iliiIiIIIJ till
- '000
-
FIGURE 9.
CLAM SURVEY TRANSECT LINES
0
1000
2000
D SAMPLE STATIONS, NETARTS BAY
3000
S
o
S
-20-
gC
gg \
gg9
gg
ggg
ggi
99g
NETART&
g
\C
'CC
CC
C
CCC CC
CC CC
:i
z
CC
I
U
0
U
LI
U
/
\
nCSCbCCCC
I
CCCC
bCCCCCCC
J
bSSg C
(/ CpflbcsS
SS
bflb
b
CC1C bC
'
(CRC
CC CCC
b
\C
5S7 C
CC
CC
U
CC\
\CC\
C
C
C
CCC\
CC
çCSC
fn
/)
CCCCCCC
CCCCC\C
C
/cCgC9
I
[
/
C
/
/
m
Jmm
/
CCC)CC
SS
gC
CCC
c4s%S
g
C
b)SSs
SS
CSCWS
/
CCCCC4SnSCCSSI.
n
,
n))
Lbb (
mm
/
/
/
4sbc
/
C
'qflCCmm
C
,mmm'h1
(,,17/i'
C
Nei-ar-i-6
#Bay
cIavYl popLAIa+io
/
'I
O41L4
sfivi i iiea
VertipJ.
p
My
C
(bi-(-teY c(awi)
b
(riahv
IiH-tieck. cicsvvt)
(offtokeJl ckiwi)
/000
DISTRIBUTION OF CLAMS IN NETARTS BAY
2000
g
ckwvi)
ppir'aru1v1 (Ma({a Ii4'flvieck_ dii)
cre11clria
0
per cavvl)
(ccxk
gisal1+eM5
Veyerc,j
/000
FIGURE 10.
(
Clinoardkiivii vU14ft,Jlii
/
pa+friis
cp.x
1vv
/
N
3000
1000 FEET
n
m
S
S
S
S
S
4
S
S
-21-
NETARTS
N
t'le*arts E
dawi populatioti pa4ferbl5
(berft'w5e ci4vrt)
ct4+o
Miwv
Macovr
baI+ii&c'
(irMs cvvi)
Mccovvv irt'is
pilsbryj
ir-fae
1L
(piciciockdakvl)
T&Iivia boc&&ns6
(bodea +eIIei cIabv)
Cyp1yc cftforviica
(Ga(H
/000
FIGURE
(bcil+ic, claw')
0
/000
DISTRIBUTION OF CLAMS IN NETARTS BAY
.2000
oftsIielI cIaw)
5O00
'000 FEET
e
a
-22-
FIGURE 12,
SUBSTRATE MATERIAL IN NETARTS BY
.
e
*
*
*
-23-
I
_____
___r
/
Netr+5
y
suk,sfrafe r,ioi-fevials
viid
scwid
skell
grove/
- -
o
FIGURE 13.
SUBSTRATE NLATERIAL IN NETARTS BAY
exJyock
.
rock
FEEr
/000
aooa
000
S
S
S
S
S
S
S
-24-
NETART5
1f____
2!
(7
2J/
I/
Netar+s&y
I
jspar&
eel
ras
/ I
11
(
/
wioderc4le
c(
FIGURE 1'4,
ce15&
- /000
I
0
EELGRASS BEDS IN NETARTS BAY
.00O
3000
lO0O
ET
60
!
/
50
July
\
F = 215
= 15.7rrra
-
/
- August ii = 250
= 20.9mm
II
-. - Sept.
40
0)
! = 100
=23.8mm
)I
10
.,.
0
0
5
10
15
20
25
30
35
40
45
50
Size (mm)
Figure 15.
Length Frequency of Gaper Clans (1976 Year Class)
from Ore-Aqua Raceway Sample, Yaquina Bay, 1976
-26-
100
80
Butter Clam
_____ Jan. 1977
= 100
X = 9.2mm
60
40
20
ci)
a)
U
0
Cockle Clam
Sept. 1976 tI = 100
= 17.1mm
60
Jan. 1977 ! = 100
40
15.6mm
20
0
0
5
10
15
20
25
30
35
40
45
50
Size (mm)
Figure 16.
Length Frequency of Cockle and Butter Clams (1976 Year
Class) from Ore-Aqua Raceway Sample, Yaquina IJay, 1976-77
-27-
9
8
7'
6(
5(
3C
2C
'C
U
5-
90
fl
80
70
60
50
40
30
20
10
0
1976
75
74
73
72
71
70
69
68
67
66
65
64
63
Year Class
Figure 17.
Age Composition of Gaper Clams, Areas 2 arid 3, Yaquina
8a,y, 1975-76
-28II
Butter
,j
=
181
SI
4c
2C
C
Littleneck
BC
= 155
i
6C
4C
2C
a)
C
U
5-
a)
0
8(
Cockle
ii
21
=
6C
4C
.
2C
Gaper
1
516
It
40
20
C
1976
75
74
73
72
71
70
69
68
67
66
65
64
63
62
Year Class
Figure 13.
Age Composition of Subtidal Clams in Area 3 of Yaquina Bay, 1976
-293O
20
Butter
H
= 49
10
i
0
1J 1
i
F
20
i
Littleneck
H
= 163
10
0
w
20
w
0
10
Cockle
= 233
_-fitiii
1)
0
11
0
50
Gaper
H
= 259
40
30
20
fl
10
0
±Hi
1975
74
73
72
1
71
70
68
67
66
65
64
63
62
Year Class
I
I.
69
1
Figure 19.
Age Composition of Subtidal Clams in Garibaldi Area of
Tillamook Bay, 1976
61
-
20
Butter
15
i
= 49
68.8
10
5
0
Littleneck 1 = 163
20
X = 36.5
15
10
y"
a)
C
a)
5
C-)
5-
0
Cockle
15
i
= 238
= 59.2
10
5
0
Gaper
i
= 259
15
10
5
o
I'
20
40
60
80
100
120
140
160
180
Size (nun)
Figure 20.
Length Frequency of Subtidal Clams in Garibaldi
Area of Tillamook Bay, 1976
-31-
fl
0
4
Figure 21.
Location of Subtidal Experimental Commercial Clam Plots, Yaquina Bay
S
-32-
1
11 iri
I'
C
1
I
f/i
Ij a a
i I
yr
/
JagJ'111:,'/jj11J
SI
Pigeon
Point
Fossil
Point
COOS BAY
2
Scale
I
(feet)
I
I
1,500
CHARLESTON
Figure 22.
I
Location of Subtidal Cornercial Clam Plots, Coos Bay, 1976
3,000
-33100
=714
G-9
80
60
40
20
fl
0
oO
--
-
G-7
-
.1
= 101
60
40
a)
20
0
a)
I
jlJ
K-3
80
=
744
60
40
20
U
--
-,
-I-.-
80
K-i
I! = 108
60
40
20
-
0
1976
15
74
I.
73 72
I--II71
70
I
69
68
67
66
Year Class
Figure 23
Age Composition of Gaper Clams in Comercial
Clam Plots, Area 2 of Yaquina 8ay, 1976
S
-34-
30
-9
[1=249
X=68.4m
20
10
-7
30
X=86.im
20
1)
C)
1 = 99
10.
C
C)
30
K-3
i=504
=59.0m
20
K-i
ii = 108
20
o
io
20
30
40
50
60
70
80
90
100
110
120 130
140
150
Size (nun)
Figure 24.
Length Frequency of Subtidal Clams in Coninercial Clam Plots,
Yaquina Bay, 1976
p
.
-35..
ii
238
U
S..
a,
1975
74
73
Figure 23.
72
71
70
69
Year Class
68
67
66
64
65
Age Composition of Commercially Harvested Gaper Clams,
Coos Bay, 1976
30
= 233
= 133.2 mm
!AiI
a,
S
4-)
C
a,
0.
I
0
o r-..N 80
90
100
110
I
120
130
140
150
160
170
180
Size (mm)
Figure 26.
Length Frequency of Commercially Harvested Gaper Clams,
Coos Uay, 1976
190
S
S
S
.
S
0
I
4-,
w
-I
"F
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
Age (months)
Figure 27.
Growth Curve of Butter Clams Planted on the Breakwater, Yaquina bay (Vertical
Lines Indicate Range in m),
1976
I
I
I
I
S
S
I IU
100
90
dO
7U
60
A)
.r:
4)
[jjJ
40
20
10
Clams planted
I
0
10
20
30
I
40
50
I
60
70
p
I
80
90
100
in 120
130
140
150
160
Age (months)
Figure 28.
Growth Curve of !at1ve Littleneck Clams Planted in Artificial Substrate Plot, Yaqulna !3ay
(Vertical Lines Indicate Range in nn), 1976
*
I,
-38-
240
220
Legal Size
203
200
180
160
I
140
120
100
80
60
40
20
S
S
0
6-67
6-72 6-73 6-74 6-75 7-76
Sampling Date
Age
0
Figure 29.
1
2
3
4
5
6
7
8
9
Growth Curve of Whale Cove Abalone (Vertical Line Indicates
Range), 1976