PRODUCTION
COMMERCIAL CLAM PRODUCTION
ANNUAL REPORT
October 1,
1, 1980 to
30, 1981
to September 30,
by
Thomas F.
F. Gauiner
Gaumer
Richard M.
M. Starr
Oregon Department of Fish and
and Wildlife
National Marine Fisheries Service
National
National Oceanic
Oceanic and
and Atmospheric
Atmospheric Administration
Administration
National
of Commerce
Commerce
United States Department of
Commercial Fisheries
Fisheries Research and Development Act
Commercial
Project Number l-lS0-R-2
1-lSO-R-2 Segment
Segment 22
Contract Number 81-ABD-ORAB
8l-ABD-ORAB
March, 1982
1982
CONTENTS
Page
INTRODUCTION . . . . . . . . . .
1
1
OF HARVEST
HARVEST POTENTIAL
POTENTIAL
ASSESSMENT OF
Methods . . . .
Methods..............................
Yaguina
Yaquina Bay . . . .
CoosBay
Coos Bay. . . ............................
. . .
Results
Results and Discussion
Yaquina Bay . . . .
Yaguina
Estimates, Area 22
Population and Biomass Estimates,
Population and Biomass Estimates,
Estimates, Area 2,
2, Plots
Plots FF and
and CG
......................
Methods
. . . .
Methods..............................
Yaquina Bay ..........................
. . . .
Coos
Bay .............................
. . . . .
CoosBay
Results and Discussion ......................
Results
Yaquina Bay ..........................
COMMERCIAL HARVEST OF CLANS
CLAMS
Coos
Coos
Bay Bay
. . . .............................
ASSESSMENT OF EFFECTS OF COMMERCIAL CLAM
CLAN HARVEST ON RECRUITMENT
.
.
.
.
Methods
....
Methods..............................
Results
and and
Discussion
Results
Discussion
LABORATORY
CLAM STUDIES
LABORATORY
CLAN STUDIES
Methods
....
Results
Results and Discussion
......................
1
1
1
1
1
1
1
1
1
1
1
1
1
77
1
77
77
77
77
88
88
88
88
88
14
14
14
........................ 14
18
.............................. 18
18
...................... 18
ACKNOWLEDGMENTS
18
............................ 18
LITERATURE CITED CITED ............................ 19
19
LITERATURE
TABLES
Number
11
Page
Population and Biomass Estimates of
of Subtidal Clams
Clams in
in Area 2,
2,
Yaquina
Bay, Bay,
1975-81.
. . . . . ........................
. .
Yaquina
1975-81
44
22
Estimated Abundance of Various
Clams, Area 2,
2,
Various Cohorts of Gaper Clams,
Oregon, 1975-81
Yaquina Bay,
Bay, Oregon,
1975-81. . . .
33
Population and Biomass Estimates of Subtidal Clams in
in Area 2,
2,
Plots
Bay, Oregon,
1981. . . . . . . . . . .
Plots F and G,
G, Yaquina Bay,
Oregon, 1981
4
4
Pounds of Clams
Clams Mechanically Harvested in Experimental Fishery,
Pounds
Yaquina Bay,
Bay, Oregon,
Oregon, 1975-81
1975-81. . . . . .
5S
Summary
Pounds of Clams Mechanically Harvested in Experimental
Summary of Pounds
Fishery,
Fishery, Coos
Coos Bay,
Bay, Oregon,
Oregon, 1975-81
1975-81..................
. . . . . . . . . . . .
.12
12
66
Subtidally from
from Coos Bay,
Bay,
Catch/Effort for Gaper Clams Harvested Subtidally
77
Summary of Total Numbers1]
Numbers 1/ of Marine Organisms Occurring
Occurring in
in
Commercially Harvested Plot
Plot CC and Control
Control of
of Area
Area 2,
2, Yaquina
Yaquina
Bay,
19811981
. . . . .............................
. . . . . . . . . . . . . . . . . . .
.22
Bay,
22
8
8
Summary of Numbers1]
Numbers 1/ of Representative Marine Organisms
Organisms Occurring
Occurring
in
2, Yaquina
in Commercially Harvested Plot
Plot C
C and Control of Area 2,
Bay,
197981. . . . . ............................
. . . . . . . . . . . . . . . . . . . . . . . 23
23
Bay,
1979-81
.................... 66
.............. 99
.................... 99
Oregon,
12
Oregon, 1981. 1981
. . . .............................
. . . . . . . . . . . . . . . . . . .
.12
FIGURES
Number
1
1
2
2
33
Page
Map of Yaquina Bay,
Bay, Showing Areas
Areas Approved for
for Commercial
Commercial Clam
Clam
Harvest
Harvest. . . ...............................
..•.•.........
. . . . • . .
Bay, Showing Area Approved for
Map of Lower Coos Bay,
for Commercial
Commercial Clam
Harvest..
.
Harvest..............................
55
Length-Class Composition of Subtidal Gaper Clams Collected from
Length-Class
from
Bay, Bay,
Oregon,Oregon,
1981.
. ...
Area 2,2,Yaquina
Area
Yaquina
1981 .................
55
33
Year-Class Composition of Subtidal Gaper Clams
Clams Collected
Collected from
from
Area 2,2,
Yaquina
Bay, Bay,
Oregon,Oregon,
1981.
• ...
Area
Yaquina
1981 .................
4
4
2
2
55
Year-Class
Subtidal Gaper Clams
Clams Collected
Collected from
from
Year-Class Composition of Subtidal
10
Plot FFofofArea
2, 2,
Yaquina
Bay, Bay,
Oregon,
1981.. 1981
. .............
..
Plot
Area
Yaquina
Oregon,
10
66
Length-Class Composition of Subtidal Gaper Clams Collected
Collected from
from
10
Plot FFofofArea
2, 2,
Yaquina
Bay, Bay,
Oregon,
1981
.
Plot
Area
Yaquina
Oregon,
1981 ............
10
(Continued)
FIGURES (Continued)
Nwnber
Number
77
8
8
99
Page
Year-Class
Subtidal Gaper Clams Collected
Collected from
from
Year-Class Composition of Subtidal
G of Area 2,
2, Yaquina Bay,
Bay, Oregon,
1981..
....
Plot G
Oregon, 1981
............
Length-Class Composition of Subtidal Gaper Clams Collected
Collected from
from
Length-Class
Plot GGofofArea
2, 2,
Yaquina
Bay, Bay,
Oregon,
1981..1981
..
...
Plot
Area
Yaquina
Oregon,
............
11
11
Year-Class
Subtidal Gaper Clams Commercially
Commercially
Year-Class Composition of Subtidal
Harvested from
from Pigeon Point
Point Area of
of Coos
Coos Bay,
Bay, Oregon,
Oregon, 1981
1981 .
13
13
.
10
10
Length-Class Composition of Subtidal Gaper Clams Commercially
Commercially
Length-Class
from Pigeon Point
Point Area of Coos
Coos Bay,
Bay, Oregon,
Oregon, 1981
1981 .
Harvested from
.
11
11
12
12
13
14
.
.
.
.
.
13
13
Nwnber of Taxonomic Groups
Groups of
of Macrofaunal Benthos
Benthos in
in Area
Area 2,
2,
Number
Treatment and
Control,
Yaquina
Bay, 1979-81.
.
Treatment
and
Control,
Yaquina
Bay, 1979-81
............
15
15
Nwnber of Benthic
Benthic Invertebrates
Invertebrates per
per ft2,
ft 2 , Area
Area 2,
2, Treatment
Treatment
Total Number
and Control,
Bay, Oregon,
1979-81. . .
Control, Yaquina Bay,
Oregon, 1979-81
16
.............
Number of Clams/ft2
Clams/ft 2 Area 2,
2, Treatment and
and Control,
Control, Yaquina
Yaquina Bay,
Bay,
Oregon, 1979-81.
. •.
..
Oregon,
1979-81
..........................
17
17
Growth Curve
Curve of Manila Littleneck
Littleneck Clams
Clams Spawned and Planted
Planted from
from
Brood Stock in
in Netarts
Netarts Bay,
Bay, 1974-81.
1974-81.
Normal and Fast Growing Brood
20
20
.
15
15
11
11
Planted in
in Fenced,
Fenced,
Growth Curve of Manila Littleneck Clams Planted
Unfenced and Eelgrass Covered Areas of
of Netarts Bay,
Bay, 1974-81.
1974-81.
.
.
.
21
COMMERCIAL CLAN
CLAM PRODUCTION
PRODUCTION
ABSTRACT
Studies on
on the
the assessment
assessment of
of harvest
harvest potential
potential in
in Yaquina
Yaquina Bay
Bay continued.
continued.
and biomass estimates, age
age and
and size
size of
of clams
clams were
were calculated
calculated for
for
Population and
an area in Yaquina Bay
Bay having commercial
commercial harvest
harvest potential.
potential. Our data revealed
that
the 1975 year-class
that the
year-class continued strong with
with over
over 88%
88% of
of the
the gapers
gapers sampled
sampled
of this age.
age. Approximately 2.5 million pounds (1,165.4
(1,165.4 mt)
mt) of
of gapers
gapers were
were
estimated for
for the
the area
area and
and aa harvest
harvest quota
quota of
of 250,000
250,000 pounds
pounds (113.4
(113.4 mt)
mt) was
was
estab
lished.
established.
We calculated estimates of
of natural mortality
mortality for
for eight
eight year-classes
year-classes of
of
clams in Yaquina Bay and they ranged from
gaper clams
from 0.12 to
to 0.89.
0.89.
Due to poor markets, none of
of the
the
This was
ermen landed
landed clams
clams in
in 1981.
1981. This
1979, 74,565
74,565 pounds (33.8
(33.8 mt) were
In 1979,
three Yaquina
Yaquina Bay
Bay commercial
commercial clam
clam fishfishthree
the
the second consecutive year of
of no harvest.
harvest.
taken.
taken.
In
(28.1 mt)
mt) of
of clams
clams were
were harvested.
harvested. Of
In Coos
Coos Bay 61,955
61,955 pounds (28.1
total,
(27.1 mt) or
Or 96.4%
96.4% were
were gaper
gaper clams.
clams. Production
total, 59,751 pounds (27.1
showed that 272
272 pounds (0.1
(0.1 mt)
mt) were
were taken/hour.
taken/hour.
this
figures
figures
revealed significant
significant differences
differences in
in population
population dendenPost harvest surveys revealed
sities, at
at the
the 95% confidence
confidence level,
level, for
for recruitment
recruitment of
of macoma
macoma and
and littleneck
littleneck
sities,
and anemones
anemones were also
clams
and control
control sites.
sites. Aniphipods
Amphipods and
clams in the treatment and
similarly
similarly impacted.
impacted. In
In general,
general, all species of
of clams
clams have revealed
revealed poor
poor sursurvival of recruitment in
in Yaquina
Yaquina Bay
Bay since
since 1975.
1975.
vival
INTRODUCTION
During
on the clam
clam resources
resoUrces in
in Oregon's
Oregon's
During the
the year
year we
we continued
continuedour
ourstudies
studies on
estuaries.
Our objectives
were: to
to collect
collect data
data for
for developing
developing aa scientifestuaries. Our
objectives were:
scientificallysound
sound clam
clam management
management data
ically
database
baseand
andtotorefine
refine techniques
techniques for
for assessing
potential for
fora acommercial
commercial clam
clam fishery
several of
of Oregon's
Oregon's estuaries.
the potential
fishery in
in several
In addition
In
addition we
we continued
continued to monitor
monitor the growth
growth of laboratory
laboratory reared
rearedManila
Manila
littleneck
clams (Tapes
(Tapes japonica)
japonica) released in
in Netarts
Netarts Bay.
Bay.
littleneck clams
ASSESSMENT
HARVEST POTENTIAL
ASSESSMENT OF
OF HARVEST
We
Area 22 in
inYaquina
Yaquina Bay
Bay to
to determine
determinethe
thecommercommerWecontinued
continuedour
our survey
survey of Area
cial
clam harvest
harvest potential
potential (Figure
(Figure 1). TIlis
area has
has been
been surveyed
surveyed and
and clam
clam
cial clan
This area
resources
every year
year since
since 1975.
1975. The
commercial clam
clam
The experimental commercial
resources inventoried every
harvesting area
areaininCoos
CoosBay
Bay surveyed
surveyed in
in1975
1975 and
and 1980
1980 was
was not resurveyed
resurveyed in
in 1981
1981
(Figure
(Figure 2).
Methods
Yaquina Bay
Bay
developed by
Washington Department
Using
Using techniques
techniques developed
by the Washington
Departmentofof Fisheries
Fisheries
(Goodwin,
[Goodwin,1973)
1973)and
and the
the Oregon
Oregon Department
Departmentof
of Fish and
and Wildlife
Wildlife(Gaumer
(Gaumer and
and
Halstead,
on the subtidal
subtidalclam
clampopulations
populations in
inYaquina
Yaquina
Flaistead, 1976)
1976) we
we collected
collected data
data on
Bay. We
We removed
samples
from
thethe
18.4
acre
Data collected
removed2424
samples
from
18.4
acre(7.4
(7.4ha)
ha) site.
site. Data
provided
population and
weight, age
age and
and species
species
provided estimates
estimates of population
and biomass,
biomass, size,
size, weight,
composition,
composition, recruitment
recruitment and
andnatural
natural mortality.
Following
two 0.9
Followingour
our assessment
assessmentofofclam
clamstocks
stocksinin Area
Area 2,
2, we
we selected
selected two
0.9 acre
(0.4
ha) sites
sitesfor
forthe
the
1981commercial
commercial clam
clam fishery.
Plot F
F was
was restricted
restricted to
(0.4 ha)
1981
fishery. Plot
the
use of
of aasuction
suctionpump
pump for
harvest and
and Plot
Plot GG was
was designated
the use
for harvest
designated for
for harvest
harvest
with
high pressure
(Figure 1). Data
collected from
from
Data similar
similar to
to that collected
with a high
pressure water
water jet
jet (Figure
Area 22 were
were obtained from
from Plots FF and
and C.
G.
Area
Coos Bay
Bay
Coos
The
thatwas
wasapproved
approvedinin1975
1975 for
forcommercial
commercial
The same
same48-acre
48-acre (19.4
(19.4ha)
ha) site
site that
Duetoto limitations
limitations in
in
harvest of
of clams
clams was
was again
again opened
opened for
the 1981
1981 season.
season. Due
for the
manpower
manpower
and
and
thethefact
factthat
that this
this area
area was
was surveyed
surveyed in 1980,
1980, we
we did
did not resurvey
resurvey
the
the harvest area
area in
in1981.
1981.
Results
and Discussion
Discussion
Results and
Yaquina
Bay
Yaguina Bay
Population
Biomass Estimates,
Area 2.
Population and Biomass
Estimates, Area
2.
Fromour
our samples
samples we
we estimated
estimated
From
This was
about one-half
12.4 million
million clams
clams inhabited
inhabited Aiea
Area 2 (Table
(Table 1). This
was about
that 12.4
the number
number estimated
1980. Gaper
Gaperclams
clams(Tresus
(TresusoapaxJ,
capax),the
thetarget
target species
estimated in 1980.
for
the commercial
commercial fishery,
with a
for the
fishery,represented
representedover
over6.1
6.1million
millionofofthis
this total
total with
Decreases
in
availbiomass
estimated
at
over
2.5
million
pounds
(1,165.4
mt).
Decreases
in
availbiomass estimated at over 2.5 million pounds (1,165.4 mt).
abilityofofgaper
gaperand
andmacoma
macoma (ktzcolna
(M::woma inquinataJ
the
ability
inquinata) clams
clamswere
wereresponsible
responsible for
for the
lower total number
number of
clams in
population.
lower
of clams
in the population.
U&
a sgiDer
~\.e" ~
vI54TOh
CIiANMFL
Clii
M4
..,.
I
N
N)
I
BOAT 645/N
BASIN
BOAT
o SU MARINE
MARINE SCIENCE
SCIENCE
Osu
CENTER
PLAN
BEACH
SOUTH OCACH
GO
!
0•
GO
JOG
!
!
JQO
•
,a,,,
III
Figure 1.
1,
Map of Yaquina Bay,
Bay, Showing Areas
Commercial Clam Harvest.
Areas Approved for Commercial
Harvest.
-3-
n
~,.--f-./.....-'P"'RM 1''1
ARr:.A
pIaCoN
pur
at
Coos"BtAy
o
Figure
2.
Figure 2.
Map of Lower
Lower Coos
Coos Bay,
Bay, Showing
Showing Area
Area Approved
Approved for
for Conunercial
Commercial Clam
Clan Harvest.
Harvest.
-4-
Table 1l.
Population and Biomass
Biomass Estimates of
of Subtidal Clams
Clams in
in Area
Area 2,
2,
Yaquina Bay,
Bay, 1975-81.
1975-8l.
Numbers
1975
1976
1977
1978
1979
1980
Gaper
Cockle
Li ttleneck
Littleneck
Butter
Macoma
Piddock
36,300,000
183,200
366,400
416,000
13,532,800
1,700,000
25,566,400
16,800
216,800
333,600
20,566,400
0
0
29,316,000
00
116,000
200,000
12,049,600
00
10,560,000
32,000
48,000
240,000
11,200,000
00
11,116,700
16,700
133,300
200,000
10,100,000
0
0
11,050,000
00
66,700
366,700
10,100,000
0
Total
52,498,400
46,700,000
41,681,600
22,080,000
21,566,700
21,583,400 12,448,000
Species
1981
6,160,000
0
0
120,000
200,000
5,968,000
0
0
Biomass (lbs)
(lbs)
Species
Gaper
1975
1976
1977
1978
1979
1980
1981
5,084,200
5,217,200
4,968,991
4,136,800
3,461,100
4,265,600
2,569,700
The year-class conçosition
composition of
of gaper
gaper clams
clams in
in Area
Area 22 is
is shown
shown in
in Figure
Figure 3.
3.
continues to represent a majority of the
the clams
clams (88.1%)
(88.1%) in
The 1975 year-class continues
in
the population. Mean age of the gapers
gapers was
was 6.3
6.3 years,
years, an
an exact
exact increase
increase of
of 1.0
1.0
years
the lack
years since 1980 illustrating the
lack of recruitment or mortality of the
the older
clams in the
set since
since 1978
1978
clams
the population. Our data reveal
reveal no survival
survival of gaper set
and very little in
in 1976
1976 and
and 1977.
1977. Surveys in 1981 were taken
taken too
too early
early to
to exexpect that
that year-class to
to show
show in
in the
the samples.
samples. Age composition
composition data
data for
for butter,
cockle and littleneck clams
cockle
clams are not presented
presented due
due to
to the
the few
few clams
clams collected.
collected.
distribution of
of gaper
gaper clams
clams from
from Area
Area 22 is
is shown
shown in
in Figure
Figure 4.
4.
The length-class distribution
Mean size was 91.7
91.7 mm,
mID, an
an increase
increase of
of 3.0
3.0 mm
mID since
since 1980.
1980.
The wide range in
Gaper clams in Area 2 exhibited a patchy
patchy distribution.
distribution. The
in
numbers of individuals
individuals observed created a large
large sample variance
variance which
which resulted
large coefficient
coefficient of
of variation
variation for
for our
Our population
population estimates.
estimates. To minimize
mlnlIDlze
in a large
the effect of the large variance
variance we
we applied an iterative numerical
numerical fitting
fitting rouroutine
(Snedecor and Cochran
tine involving the
the least
least squares
squares technique
technique (Snedecor
Cochran 1978)
1978) to
to gaper
gaper
clam population estimates.
estimates.
University's CDC CYBER 170/
We utilized the CURFIT program in Oregon State University's
170/
720
fit" regression
regression line
line for
for eight
eight gaper
gaper clam
clam cohorts.
cohorts.
720 computer to plot a "best fit"
Observed numbers of clams
clams were
were too
too small
small or inconsistent to
to obtain realistic
realistic
regression lines for
for the 1963-66, 1973,
1973, 1974,
1974, and
and 1977-80
1977-80 year-classes
year-classes. From
the
lines we obtained
obtained estimates
estimates of
of natural
natural mortalmortalthe eight plausible regression lines
.(M) and
and cohort
cohort abundance
abundance through
through time
time (Table
(Table 2).
2).
ity (M)
Estimated M
M values
values ranged from 0.12 to
to 0.89
0.89 which indicates
indicates vastly difdifferent
rates of natural mortality between
between year-classes.
year-classes. These data may
may be
ferent rates
-5-5-
---
SO
Sc
eo
N = 370
370
N
x age
age == 6.3
6.3 years
years
70
7C
4J
Ui
(9
'U,
"
r-- .-
2.:
z
4J
Ui
()
C7
0::
a:
W
LI
Q.,
a-
60
"',
-'"
40
30
3c
ZO
10
..
0I
,
-,-
80
79 78
78 77
77 76
76 75
75 14
74 73
73 7Z
7Z73.
71
80 75
70
68
ID 65 68
'YEAR-CLASS
YEAR-CLASS
Figure 3
Figure
3.
Year-Class Composition
of Subtidal
Subtidal Gaper
Gaper Clams
Clams Collected
Collected from
from
Year-Class
Composition of
Area
Yaquina Bay,
Bay, Oregon,
Oregon, 1981.
1981.
Area 2,
2, Yaquina
.
30
N = 369
369
N
x
si ze ==91.7
R size
91. 7niii
mm
w
LI
CD
(!)
<r:
ZO
zo
tI-
:z
2
~
W
LI
.-
()
C,
0::
a:
LI
W
Q.,
a-
I-
10
.-.-
.....
....
I-
I.t
. r-f":"
o0'
I
I
I
I
I
zo
20
I
I
I
40
I
I
I
~
~
, ,
I'i'I'i'I'I'I'i'I'I' IuI,I,I,L.J.1.I,j-.
60
00
80
90
100
see
1Z0
120
140
540
LENGTH-CLASS
(MM)
LENGTH-CLASS (MM)
4
Figure 4.
-
Length-Class Composition
of Subtidal
Subtidal Gaper
Gaper Clams
Clams Collected
Collected from
from Area
Area 2,
2,
Length-Class
Composition of
Yaquina Bay,
8ay, Oregon,
Oregon, 1981.
1981.
Yaquina
Table 2.
2.
Estimated Abundance
AblIDdance of
of Various Cohorts
Cohorts of
of Gaper
Gaper Clam,
Clam, Area
Area 2,
2, Yaquina
Yaquina Bay,
Bay, Oregon,
Oregon, 1975-81
1975-81
YEAR
May
1977
Feb.
1978
March
1979
Year
Class
Sept.
1975
Oct.
1976
1967
395,800
151,200
89,379
45,815
17,502
1968
1,193,200
295,750
138,040
53,080
1969
1,627,700
617,150
366,610
1970
981,720
470,080
1971
250,600
1972
March
1980
March
1981
M
M
-
--
0.89
12,988
--
--
0.12
185,280
70,249
--
--
0.89
314,380
188,520
90,272
45,649
23,084
0.68
218,960
203,400
185,210
161,830
142,820
126,050
0.12
2,031,300
1,180,900
878,090
602,500
350,270
211,980
128,290
0.50
1975
42,663,000
29,851,000
24,560,000
19,166,000
13,410,000
9,634,700
6,922,000
0.33
1976
--
6ll
,020
611,020
494,
llO
494,110
364,620
245,530
170,250
ll8,050
118,050
0.36
I
0'
I
-7-
misleading;
low sample numbers of
of old
old clams
clams and
and diffidiffimisleading; however,
however, because the low
culty in accurately aging clams older than 55 years may bias the
the abundance
abundance
culty
estimates. Our
Our abundance
abundance estimates
estimates of clams less than 5 years old
old are
are probably more accurate
accurate because of
of greater
greater aging
aging reliability
reliability and
and larger
larger sample
sample numnumbers.
bers. Consequently,
the M
representaConsequently, the
N value range of 0.33 to 0.50 may be more representative
tive of gaper clam
clam cohorts
cohorts in
in Yaquina
Yaquina Bay.
Bay.
Biomass Estimates, Area
Area 2,
2, Plots
Plots FF and
and C.
G. We estimated
estimated
Population and Biomass
that
clams inhabited Plot F and 950,000
950,000 occurred in
in Plot
Plot CG (Table
(Table 3).
3).
that 720,000 clams
Of the
the total
total number of clams in Plot F,
F, 492,000
492,000 were gaper
gaper clams
clams weighing
weighing an
an
estimated 152,200 pounds
pounds (69.0
(69.0 mt).
mt). Of
Of the
the total
total clams
clams in
in Plot
Plot C,
G, 370,000
370,000
an estimated
estimated 207,500
207,500 pounds
pounds (94.1
(94.1 mt).
mt). In
95%
were gapers weighing an
In excess
excess of 95%
of the
year-class, whereas 76%
76% of
of the
the gapers
gapers in
in
the gapers
gapers in Plot F were the 1975 year-class,
Plot
(Figures 55 and
and 7).
7). In
Plot G
C were the 1975 year-class (Figures
In neither plot did we
observe any gapers
gapers from the 1976 through 1981
1981 year-classes. Mean age of gapers
from
G was 6.2
6.2 and 6.5 years,
years, respectively.
respectively.
from Plots
Plots F and C
frequency of gaper clams
clams in
in Plots
Plots FF and
and CG is
is shown
shown in
in Figures
Figures 66
Length frequency
and
8. In
In Plot
Plot F,
F, mean size
size of
of the
the clams
clams in
in the
the preharvest
preharvest sample
sample was
was 84.1
84.1 nun,
mm,
and 8.
whereas gapers
gapers in
in Plot
Plot CG averaged
averaged 101.2
101.2 mm.
mm. Capers
Gapers sampled in
in Area 22 averaged
averaged
year-class gapers
gapers in
in Plots
Plots F and
and G
C was
was 82.3
82.3 mm
mm
91.7 mm.
mm. Mean size of 1975
1975 year-class
and 93.9
93.9 nun,
mm, respectively.
difference reflects
reflects the
the possible
possible impact
impact
respectively. This size difference
of crowding on the two populations of clams since
since densities
densities in
in Plot
Plot FF were
were conconsiderably higher.
COMMERCIAL HARVEST OF CLAMS
In 1981,
commercial clam
clam fishermen
fishermen to
to mechanmechan1981, we issued eight permits to commercial
ically harvest subtidal clams in experimental test
test plots. Permits were
required because the
the use of
of mechanical means
means to
to harvest
harvest clams
clams is
is tmlawful.
unlawful.
specified the
the pounds of
of clams
clams that
that could
could be
be harvested,
harvested, season,
season,
The permits specified
Additionally, monthly reports
harvest area
area and
and harvest
harvest equipment.
equipment. Additionally,
reports giving
pounds and numbers of clams
clams harvested and
and hours
hours of effort
effort were
were required
required of
of
each
operator. The season
season started
started July
July 1,
1,1981,
December 31,
31, 1981.
1981.
1981, and ended December
each operator.
Methods
Yaquina Bay
Three commercial
commercial clam harvesting permits
permits were
were issued for
for Yaquina
Yaquina Bay
Bay in
in
1981.
One permit was
for Plot F (suction
(suction pump site)
site) and
and aa quota
quota of
of
was issued for
1981.
125,000 pounds
pounds (56.7
(56.7 mt)
mt) of
of gapers
gapers was
was set.
set. The other two
two permits were
were issued
issued
for
for Plot C
G (water
(water jet site);
site); an additional quota
quota of
of 125,000
125,000 pounds
pounds (56.7
(56.7 mt)
mt)
pounds (113.4
mt) allocated for
for harvest
harvest
was placed
placed on
on this
this plot.
plot. The 250,000
250,000 pounds
(113.4 mt)
was
was 10% of
of the
the available
available biomass
biomass of
of gaper
gaper clams
clams in
in Area
Area 2.
2.
was
Coos
Coos Bay
commercial clam
clam harvesting
harvesting permits
permits were
were issued
issued for
for Coos
Coos Bay.
Bay. Four
Five commercial
of the permits allowed the use of a water
water jet
jet to
to harvest
harvest clams
clams while
while the
the reremaining permit
permit was
was issued
issued for
for aa suction
suction pump
pump with
with aa subsurface
subsurface discharge.
discharge. A
A
maining
Both pump and
quota of 100,000 pounds (45.4
(45.4 mt)
mt) was set
set for
for the
the area.
area. Both
and jet
jet
(Figure 2).
operators
in the
2).
operators worked in
the same
same area
area adjacent
adjacent to
to Pigeon
Pigeon Point
Point in
in Coos
Coos Bay
Bay (Figure
species composition.
We
composition.
We sampled the commercially harvested clams
clams for
for size,
size, age
age and species
-8-
Resul
ts and Discussion
Dis cussion
Results
Yaquina Bay
No
Yaquina
harvest
over of
commercially harvested
harvested in
in the
the experimental
experimental fishery
fishery in
in
clams were commercially
Bay
Bay during
during 1981.
1981. This
consecutive year that
that no
This was
was the second consecutive
occurred in
in Yaquina
Yaquina Bay
Bay (Table
(Table 4).
4). A
A lack
lack of markets plus aa carrycarryoccurred
frozen
frozen clams
clams from
from the
the 1979
1979 season
season constrained
constrained the
the commercial
commercial fishery.
fishery.
Bay
Coos Bay
The commercial
commercial harvest in Coos Bay
Bay produced
produced 61,955
61,955 pounds
pounds (28.1
(28.1 mt)
mt) of
of clams
clams of
The
which 59,751
59,751 pounds
pounds (27.1
(27.1 at)
mt) or
or 96.4%
96.4% were
were gaper
gaper clams
clams (Table
(Table 5).
5). The
which
The
remainder were
remainder
were butter
butterclams
clams(SctxLdomui3
(SaudomLU g-gan-teao).
g.-i.gcm:teLU). The
The fishery extended from
August through December 1981. Divers averaged
averaged 2.8
2.8 hours of
of dive
dive time
time each
each
trip.
Harvest figures
figures revealed
revealed that
that in
in 1981,
1981, clam
clam catch
catch per
per unit
unit effort
effort was
was
272
(124 kg/hr) or 608 pounds/trip
pounds/trip (276
(276 kg/trip)
kg/trip) (Table
(Table 6).
6). Clams
272 pounds/hour (124
Clams
harvested in
in 1981
1981 were
were delivered
delivered to
to different
different buyers
buyers than
than in
in previous
previous years
years
harvested
due
between 1975
1975 and
due to the effects
effects of
of aa soft
soft market.
market. Most
Most clams
clams harvested between
1980 were processed and then shipped
shipped out-of-state.
out-of-state. The
the 1981 harThe bulk of the
vest
Bay markets.
markets.
vest was
was sold through local Coos Bay
clams averaged 7.6
7.6 years
Gaper clams
years of age
age with
with the
the 1973
1973 year-class
year-class producing
producing
over 42%
42% of
of the
the harvest (Figure
(Figure 9).
9). The clams averaged 133.7
over
133.7 mm which was
was
exactly the same mean size as clams
clams harvested
harvested in
in 1980
1980 (Figure
(Figure 10).
10).
ASSESSMENT OF EFFECTS OF COMMERCIAL CLAM HARVEST ON RECRUITMENT
One of the
the primary concerns
concerns with a new commercial
commercial clam fishery
fishery is
the
is the
might have on
on future
future recruitment.
recruitment. Ideally,
Ideally, a portion of
effect the harvest might
existing stocks
stocks are
are available
available for
for harvest
harvest and
and the
the remaining
remaining clams
clams serve
serve as
as
the existing
brood stock
stock capable
capable of
of reseeding
reseeding the
the harvest
harvest areas.
areas. One
One basic
basic objective
objective of
brood
our studies was
determine if the
the harvested areas
areas Were
was to determine
were being reseeded by
by adjaadjacent
cent brood
brood stock.
stock.
Methods
The
The area selected for
for evaluation was
was commercially harvested
harvested by
by suction
suction pump
pump
in 1978 (Gaumer
(Gaumer et
et al.
a1. 1978),
1978). Sampling methods were the same as reported
reported in
1979 (Gaumer
(Gaumer et al.
a1. 1979),
(Gaumer
1979), with
with slight modification
modification as
as reported in
in 1980
1980 (Gaumer
2 ) were
and Robart
Robart 1980).
1980). Twelve
(0.09 m
Twelve individual
individual samples
samples of 11 ft2
ft2 (0.09
m2)
were collected
the treatment area in both
from the
both June
June and September 1981. Similar numbers
numbers of
taken from
from an
an adjacent
adjacent control
control area
area during
during the
the same
same time
time periods.
periods.
samples were taken
All
All benthic samples
samples were
were bagged,
bagged, labeled and returned
returned to
to the
the laboratory,
laboratory,
all invertebrates were sorted
sorted into
into taxonomic
taxonomic groups.
groups. Invertebrates
and all
Invertebrates easily
identified were
were separated
separated into
into species
species while
while all
all others
others were
were grouped
grouped by
by family,
family,
identified
or phyla.
phyla. A
analysis of variance was applied
applied to
to representative
representative
order, or
A two-way analysis
Or groups
groups of invertebrates
invertebrates to test for
for possible variation due to temspecies or
poral separation
separation of
of sampling
sampling periods.
periods. Since our data showed no variation
variation due
due
in different
different time periods,
analysis of variance was
to sampling in
periods, a one-way analysis
was utiutilized as
as a
a more
for evaluating differences
differences in
more powerful
powerful test
test for
in number
number of
of taxonomic
taxonomic
groups
treatment and control.
control.
groups between treatment
-9-
Table 3.
3.
Population and
Population
and Biomass Estimates of Subtidal Clams in
in Area 2,
2,
Plots FF and
and G,
G, Yaquina Bay,
Bay, Oregon,
Oregon, 1981.
1981.
Plot FF
Number
Biomass
Species
Plot CG
Number
Biomass
(lbs)
(lbs)
Gaper
492,000
152,200
370,000
207,500
Cockle
00
Butter
4,000
Littleneck
4,000
4,000
"
"
5,000
"U
"
Macoma
220,000
"
"
560,000
"
"
TOTAL
720,000
950,000
207,500
Table 4.
4.
0
0
calculated
Not calculated
II
15,000
152,200
calculated
Not calculated
Pounds of Clams
in Experimental
Clams Mechanically Harvested in
Experimental Fishery,
Fishery,
Yaquina
Yaquina Bay,
Bay, Oregon,
Oregon, 1975-81.
1975-81.
Year
Species
1975
1975
1976
1977
1978
1979
1980
1981
1,478
00
68,074
162,351
73,959
00
00
305,862
24
24
00
10
10
0
0
00
00
00
34
34
Littleneck
00
00
49
11
00
00
00
50
Butter
00
00
590
22
22
606
00
00
1,218
Irus
00
00
334
44
00
00
00
378
1,502
00
69,057
162,418
74,565
00
00
307,542
Gaper
Cockle
TOTAL
Total
-10100
-
SO
90
=
N
N = 98
98
x age
age = 6.2
6.2 years
years
Go
SO
W
70
<r:
[;0
(})
CD
II2
_1 :
0a
a::
uJ
W
a...
=
50
40
43
30
tui
ZO
70
10
i0
0
•
SO
75 74 73 7Z 7.
71 70
70 E9
6.9 6El
90 73
79 7B
79 77
77 76
7G 75
9
YEAR-CLASS
YEARCLASS
Figure
Figure 5.
5.
Year-Class
of Subtidal
Clams Collected
Collected from
from
Year-Class Composition
Composition of
Subtidal Gaper
Gaper Clams
Plot
F of
of Area
2, Yaquina
Yaquina Bay,
Bay, Oregon,
Oregon, 1981.
1981.
Plot F
Area 2,
30
N
98
N =
= 98
x size
size =
= 84.1
84.1 mm
mm
w
<r:
hi
(})
-
ZO
I-
2:
2
-
W
hi
o
C-,
0::
a::
hi
~
a.
10
-
-
o011111
..r
l-1-:-rlTI
r.1
liii IIII'I'I'I'I'l'I't'I'I'I'l'l'I'I'I'I'II-'
•
GO0
140
SOo
100
1~0
20
120
40
LENGTH-CLASS
(MM)
LENGTHCLASS (MM)
Figure
Figure
6.
6.
Length-Class Composition
Composition of
Length-Class
of Subtidal
Subtidal Gaper
Gaper Clams
Clams Collected
Collected from
from
Plot FF of
of Area
2, Yaquina
Yaquina Bay,
Bay, Oregon,
Oregon, 1981.
1981.
Plot
Area 2,
-11-
SO
so
90
80
-
70
Ui
W
(!)
a)
GO
;-"
2
5C
c
40
<r:
C
W
Ui
()
N
N = 74
74
age
6.5 years
years
X age "" 6.5
~
W 30
W30
C0...
ZO
70
-
10
to
f--
~
0
Li
70 G3
70
65 E
6'"
go 7.9
73 7
17 7G
80
7'" 77
76 15
75 74
74 73
73 17
7Z 71.
71
YEAR-CLASS
YEAR-CLAGS
Figure
Figure
7.
7
Year-Class
Collected
Year-Class Composition
Composition of
of Subtidal
Subtidal Gaper
Gaper Clams
Clams Collected
from
2, Yaquina
Yaquina Bay,
Bay, Oregon,
Oregon, 1981.
1981.
from Plot
Plot G
G of
of Area
Area 2,
30
N = 74
74
N
size
101. 2 mm
mm
size = 101.2
x
w
Li
(!)
<r
eo
r-
l-
z
W
()
~
W
a.
r-
10
-r-
0-
-
-
r-
f-
-r-
r.•
oL1
eo
Z0
40
SOO
• • • •
80
BC
100
-
. .
IZO
12:0
.
,1.1
140
LENGTH-CLASS
(MM)
LENGTH-CLASS (MM)
Figure
Figure 8.
8.
Length-Class
Clams Collected
Collected from
from
Length-Class Composition
Composition of
of Subtidal
Subtidal Gaper
Gaper Clams
Plot
2, Yaquina
Yaquina Bay,
Bay, Oregon,
Oregon, 1981.
1981.
Plot G
G of
of Area
Area 2,
-12-
Table 5.
5.
Table
Sununary
Pounds of Clams Mechanically Harvested
Harvested in
in Experimental
Experimental
Summary of Pounds
Fishery, Coos Bay, Oregon,
Oregon, 1975-81.
1975-81.
Fishery,
Year
1975
Species
Gaper
Butter
Li
Littleneck
ttleneck
Total
Table
Table 6.
6.
1976
1977
1978
1979
1980
1981
14,467
102,442
11,931
11
,931
36,744
13,351
60,616
59,751
735
1,142
0
0
0
0
39
125
2,204
00
00
0
0
0
0
511
0
0
0
0
15,202
103,584
11
,931
11,931
36,744
13,901
60,741
61,955
Harvested Subtidally
Subtida11y from
from Coos
Coos Bay,
Bay,
Catch/Effort for Gaper Clams Harvested
Oregon, 1981.
1981.
Year
Effort
1975
1976
1977
1978
1979
1980
1981
Pounds/trip
761
1,078
852
852
1,225
1,214
1,174
608
Pounds/hour
193
223
157
250
275
283
272
-13-
SO
90
SO
so
N
160
N = 160
7.6 years
years
xx age
age = 7.6
7'0
70
W
Lti
&0
@
(p50
<I:
C
l-
so
2
W
w
4Q
040
()
,.--
a::
a:
w
tIJ3fJ
3D
a..
a-
,.--
£0
to
-
111
to •
0U
•
.
•
-
.
•
8D
7.9 78
76 75
75 74
74 73
73 7Z
7271.
71 7Q
68
tSU
Y
7 .77
77 VS
70 76 60
YEAR-CLASS
Figure
9.
Figure 9.
Year-Class
Composition of
Gaper Clams
Year-Class Composition
of Subtidal
Subtidal Gaper
Clams Commercially
Commercially
Harvested
from Pigeon
Pigeon Point
Point Area
Area of
of Coos
Coos Bay,
Bay, Oregon,
Oregon, 1981.
1981.
Harvested from
3D
30
160
N = 160
N
=
133.7 mm
mm
size = 133.7
x size
x
-
111
vu
r-
1-
2
UI
0
-
r-
DC
-
UI
a-t0 •
f-
II0
.•
.• .• • •
EU
•
. .
.. ..--.--.4D
40
SO
.
. .
. .
-.- -.--.SO
B!)
. r. .
1QD
£00
SEQ
.
1.40
n
• • •
UiO
£60
LENGTH-CLASS
(MM)
LENQTH-CLASS thiN)
Figure
10.
Figure 10.
Length-Class
Length-Class Composition
Composition of
of Subtidal
Subtidal Gaper
Gaper Clams
Clams Commercially
Commercially
Harvested from
from Pigeon
Pigeon Point
Point Area
Area of
of Coos
Coos Bay,
Bay, Oregon,
Oregon, 1981.
1981.
-14-
Results
and Discussion
Discussion
Results and
Table
macrobenthic data
1981 from
Table 77 presents
presents the
the macrobenthic
datacollected
collected in
in 1981
fromthe
thetreattreatment and
of Area
Area 2,
2, Plot
PlotC,C,Yaquina
Yaquina Bay.
Bay. Six
of clams
clams
ment
and control
control plots
plots of
Six species of
and
48 other
other taxa
and 48
taxa of
of benthic
benthic invertebrates
invertebrateswere
were recorded.
recorded. Macoma
Macoma (Macoma
(Macornasp.)
ep.)
and
clams were
species of clams
clams collected. Densities
Densities of
and butter
butter clams
werethe
the principal
principal species
organisms were
same for
the May
May treatment
and
benthic organisms
werenearly
nearly the
the same
for the
treatment and
and contrOl,
control, and
September
September treatment
treatment samples.
samples. On
On the
considerable increase
increase in
in
the other
other hand,
hand, aa considerable
density
occurred for
for the
theSeptember
September control
control sample.
sample. Some
Some of
increase was
was
density occurred
ofthis
this increase
attributed
successfulrecruitment
recruitment
macoma clams.
clams.
attributed totosuccessful
ofof
macoma
A
A one
one way
wayanalysis
analysis of variance
variance was
was performed
performed to
to compare
compare the numbers
numbers of
selected
benthic invertebrates
invertebrates inhabiting
inhabiting the
the treatment
treatment and
and control
control plots
plots
selected benthic
since 1979
1979 (Table
(Table 8). Fourteen
Fourteen of
the 18
18 taxa
taxacompared
compared showed
showed no
of the
nosignificant
significant
differences
differences in
in population
popUlation densities
Ilensities atatthe
the95%
95% confidence
confidence level. Significant
differences
were recorded
recorded for
forinacoma
macoma and
and littleneck
littleneckclams,
clams,amphipods
amphipods and
andanemanemdifferences were
ones.
Analysis
variance also
also showed
showed that
taxonomic diversity
di versi ty between
between the
Analysis of
of variance
that taxonomic
treatment and
significantlyeither
eitherininnumbers
numbers of
of
treatment
andcontrol
controlplots
plots did
did not
not differ
differ significantly
figures show
that
taxa represented
represented or
densities (Figures
(Figures 11
11 and
and 12).
12). Both
Both figures
show that
taxa
or in densities
benthic invertebrates in
in both
both treatment
treatment and
and control
control plots
plots reached
reached equilibrium
equilibrium
benthic
within aa year
after harvest.
harvest.
within
year after
Figure
Figure 13
13 shows
showsthethepost
postharvest
harvestdensity
densityofofgaper,
gaper,butter,
butter, and
and littleneck
littleneck
clams in both
both control
control and
and harvest areas.
areas. Clam
Clam densities
each species
species
clans
densities for each
remained
control plots and
and
remainednearly
nearlyconstant
constantthroughout
throughoutthe
thestudy
studyperiod
periodinin the
the control
for butter
butter and
and littleneck
littleneck clams
clams in
in the
the harvested
harvested area.
area. Gaper
Gaper clams,
for
clams, on
on the
hand, exhibited considerable
considerable recruitment
recruitment in
the treatment
treatment area.
area.
May
other hand,
in the
samples in
1979 and
and 1980
1980 revealed
evidence of
ofnew
new recruitment,
whereas
samples
in 1979
revealed strong evidence
recruitment, whereas
fall
samples during
during these
these years
years showed
showed poor
these brood
brood years.
years.
fall samples
poor survival
survival for these
The June
from the 1981
1981 yearThe
June 1981
1981sample
samplerevealed
revealednonoevidence
evidenceofofsuccessful
successful set
set from
yearcl ass.
class.
Studies
Studies performed
performed at
at the School
School of Fisheries,
Fisheries,Oregon
Oregon State
StateUniversity
Uni versi tyMarine
Marine
Science Center,
the reproductive
reproductive conconScience
Center, have
have revealed
revealed considerable
considerable differences
differences in the
di
tion of
ofgaper
gaperclams
clams ininYaquina
Yaquinaand
and Coos
Coos bays.
bays. Observations
dition
Observations during
during the
the winter
spawning
spawning seasons
seasonsof
of 1980
1980and
and1981
1981revealed
revealedthat
that adult
adult gapers
gapers did
did not
not come
come into
into
spawning condi
tion in
inYaquina
Yaquina Bay.
Bay. On
hand, gapers
gapers collected
collected from
from
spawning
condition
Onthe
the other
other hand,
Coos
ripe gonads
gonads (Wilbur
(Wilbur
CoosBay
Baycame
cameinto
intocondition
conditionboth
bothyears
years and
andcontained
containedfull
full ripe
Breese,
pers. comm.).
comm.). To
Breese, pers.
To date
date no
no explanation
explanation has
has been
been offered.
offered.
LABORATORY
LABORATORY CLAM
CLAM STUDIES
STUDIES
Our
clam studies
were terminated in
in 1975.
1975. Since then
then we
we have
have
Our laboratory
laboratory clam
studies were
annually monitored
monitored the
growth of
clams planted
Netarts Bay,
Bay.
annually
the growth
of clams
planted in
in Netarts
25
Treatment
---
Control
20
Vl
-- --
§'
gg
U
°
-g
/
r-
<5
C
/
15
/
o0
C
"~0
'"
,,
/
.--_/
E-<
/
/
4-<
4-i
o0
H
§I'"
C)
10
/
z
Z
5
o0
3/79
3/79
Figure 11
11.
5/79
11/79
5/80
9/80
6/81
9/81
Number
Taxonomic Groups
Treatment and
Nuther of
of Taxonomic
Growsof
of Macrofauna1
MacrofaunalBenthos
Benthosinin Area
Area2,2, Treatment
and Control,
Control,
Yaquina
Bay, 1979-81.
Yaquina Bay,
I
....
tn
U1
I
100
/\
/
//
/
\
/
80
r#I
Treatment
\
/ /
\
/
Control
/
/
\\
~\ \
/
.
/ /
/
N
4.4
"-'
"-
....
if)
/
/
\
/
60
\
\
/
4)
+'
/
/
'-4
'"
\
;:J
"">-
\---
'H
'M
'H
'M
- -- -
/
/
,
H
-I
-ci
""<::
0'
0"
I
H
"-'
00
4-4
40
ill
.
a0
Z
z
20
a
Nov.
Nov. 1979
1979
May 1980
May
Sept.
1980
Sept. 1980
May
May 1981
1981
Sept. 1981
DATE
Figure 12.
Figure
12.
Total Number
Number of
ft 2 , Area
Area 2,2,Treatment
Treatmentand
andControl,
Control,Yaquina
Yaquina. Bay,
Bay,
Total
ofBenthic
!3enthicInvertebrates
Invertebrates per
per ft2,
Oregon, 1979-81.
1979-81.
Oregon,
-17-17--
20
20
Clam
Littleneck Clan
10
10
o
0
- ---
-------------------Butter Clam
Clan
10
10
'"'H
~
'<Il
I'i
0
--
---
---- -------
"
- -
.-<
u
Gaper Clam
C-)
'H
t44
.
00
40
4Q
A
0
0
zz
Treatment
- - - Control
Control
- --*-
30
30
20
10
10
.... ....
o
- -- -.
3/79
Figure 13.
13.
5/79
11/79
5/80
9/80
6/81
9/81
Clams/ft. 2 Area 2,
2, Treatment
Number of Clams/ft.2
Treatment and Control,
Control, Yaquina
Bay,
1979-81.
Bay, Oregon, 1979-81.
-18-
Methods
Two
studies were
were continued
continued in
in Netarts
Netarts Bay.
Bay. One
No studies
One
characteristics
clams that were
characteristics of Manila littleneck clams
growing
vs. normal
clams (Gaumer
(Gaumer and
and
growing ability vs.
normal growing clams
compared growth of clams
vs.
clams in a screened enclosure vs.
growth
compared the growth
selected for
for their
their fast
fast
selected
Lukas, 1975);
1975); the
the other
other
Lukas,
unscreened areas.
areas.
unscreened
Res u1 ts and Discussion
Dis cussion
Results
Manila littleneck clams
clams spawned
spawned in
in August 1974
1974 from
from fast
fast growing
growing parent
parent
stock grew 1.2 mm from June 1980 to
to June
June 1981
1981 and
and averaged
averaged 40.4
40.4 mm
mID in
in length,
length,
from the
the "normal" clams
clams grew 1.1
whereas progeny from
1.1 mID
mm and averaged 38.4 mID
mm
(Figure 14).
Manila clams planted in the
the screened
screened test
test plot
plot averaged
averaged 40.2
40.2 mm,
mID, an
an inincrease
crease of
of 1.6
1.6 mID
mm since
since 1980,
1980, whereas
whereas clams
clams planted
planted in
in an
an adjacent
adjacent unscreened
unscreened
test plot averaged 41.5 mm,
mID, an
an increase
increase of
of 1.5
1.5 mm.
mID.
adjacent
Manilas planted
planted adjacent
to
43.8 mm
mID in
in mean
mean length,
length,
to an
an eelgrass
eelgrass bed and at
at slightly lower elevation were 43.8
a decrease of 1.1 mm
mID since 1980
1980 (Figure
(Figure 15).
15). The
The small
small sample
a
sample size probably
decrease. Clams
all three test plots averaged
averaged 13.1
13.1 mm
mID when
when
created this decrease.
Clams in all
released.
Several dozen adult
adult Manila clams,
clams, collected
collected
to the Oregon State University
University
were brought back to
conditioned and
and spawned
spawned
tory where Wilbur Breese conditioned
date an
an uncounted number of juvenile
produced to date
into Netarts Bay
Bay in
in June
June 1982.
1982.
back into
adjacent to
to the
the test
test plots,
plots,
adjacent
Marine Science Center
Center laboraMarine
them with
wi th success.
success. This effort
them
clams which will be released
clams
ACKNOWLE DGMENTS
ACKNOWLE
DGMENTS
McCrae, Jim Golden and Steve Johnson
We wish to thank Laimons Osis, Jean McCrae,
of the Oregon Department
Department of Fish
Fish and Wildlife,
Wildlife, and Marian
Marian Asche
Asche for their assistassistance
study.
ance in the study.
-19-
LITERATURE CITED
Gaumer,
Gaumer, Thomas F.
F. and
and Bruce
Bruce C.
G. Haistead.
Hals tead. 1976. Methods
Methods of
0 f Supplementing
Clam and Abalone Production.
Production. Comm.
and Devel.
Dever. Act,
Acto July 1,
1,
Comm. Fish.
Fish. Res.
Res. and
1975 to June 30,
1975
30, 1976.
1976. Ore.
Dept. of Fish and
and Wildlife Proc.
Proc. Rept.
Rept.
Ore. Dept.
65 pp.
pp.
65
Gaumer, Thomas F.
F. and
and Gerald
Gerald Lukas.
Lukas. 19750
Methods of Supplementing Clam
Gaumer,
l975
and Abalone Production. Comm.
Comm. Fish.
Fish. Res.
Res. and
and Devel.
Devel. Act.
Act. July 1, 1974
30, 1975.
1975. Fish Comm.
to June 30,
of
Ore.
Proc.
Rept.
Comm.
Ore. Proc. Rept. 34
pp.
34 pp.
Gaumer,
F. and
and Gregory
Gregory P.
P. Robart.
Robart. 1980. Commercial Clam
Clam Development.
Development.
Gaumer, Thomas F.
Comm.
Fish. Res.
Res. and
and Devel.
Dever. Act.
Act. October 1,
1, 1979
1979 to
to September
September 30,
30, 1980.
1980.
Comm. Fish.
Ore. Dept.
Ore.
Dept. of
of Fish
Fish and
and Wildlife.
Wildlife. Proc.
Proc. Rept.
Rept. 24
pp.
24 pp.
Gaumer,
F., Gregory
Gregory P.
P. Robart
Robart and
and Anne
Anne Geiger.
Geiger. 1978. Oregon Bay Clam
Gaumer, Thomas F.,
Distribution,
and Effects
Effects of
of Harvest.
Harvest. Comm.
Distribution, Abundance, Planting Sites and
Fish.
Res. and
and Devel.
Devel. Act.
Act. October 1, 1977 to
to September
September 30,
30, 1978.
1978. Ore.
Fish. Res.
Dept.
Dept. of
of Fish
Fish and
and Wildlife.
Wildlife. Proc. Rept.
Rept. 65
pp.
65 pp.
Gaumer,
F., Gregory P.
P. Robart
Robart and
and Anne
Anne Geiger.
Geiger. 1979. Oregon Bay Clam
Gaumer, Thomas F.,
Distribution,
Abundance, Planting
Planting Sites
Sites and
and Effects
Effects of
of Harvest.
Harvest. Comm.
Distribution, Abundance,
Fish.
Res. and
and Devel.
Devel. Act.
Act. October 1, 1978 to
to September
September 30,
30, 1979,
1979. Ore.
Fish. Res.
Ore,
Dept.
Fish and
and Wildlife. Proc. Rept.
Rept. 47
pp.
Dept. of Fish
47 pp.
Goodwin, C.L.
C.L. 1973. Distribution and
and Abundance
Abundance of
of Subitidal
Subtidal Hard-shell
Clams
Hard-shell Clams
Wash. Dept.
Dept. of
of Fish.
Fish. Tech.
Tech. Rept.
Rept. No.
No. 14.
14.
in Puget Sound, Washington. Wash.
81 pp.
pp.
81
Snedecor, George
George W.
W. and
and William
William G.
G. Cochran.
Cochran. 1978. Statistical Methods.
Methods.
Snedecor,
Sixth Edition.
Edition. The
University Press.
Press. 593
593 pp.
pp.
The Iowa State university
-
Normal Growing
Growing Brood
Brood Stock
Stock
Fast Growing Brood
Brood Stock
40
30
".
,;
j
.c
..,
-'
--
-
~.
- -' - - - - - - -_.
-'
.
,;
-c
,;
1-
I
N)
N
,;
o
C
I
".
bO
<!J
.:------
,,'
-
,;
'--'
...,-'C"
".
--- -
- .---..-- - - - - =-------
,; "
20
20
,;
/
.
/
/
/
/.
/
...._~
10
10
oii
o
0
10
10
20
30
30
40
40
so
50
60
60
70
70
80
80
90
90
Age
(months after
after release)
release)
Age (months
Figure 14.
14.
Growth
Clams Spawned and Planted from Normal
Normal and Fast
Fast Growing
Growing Brood
Brood
Growth Curve
Curve of Manila Littleneck Clams
Stock in Netarts Bay,
Bay, 1974-81,
1974-81.
50
ta
Eelgrass
-.
-. -- ' -.
Unfenced
Fenced
~---_._----
.- ------_.
40
0
.-.- _.- ---_.-... -.. -'"
----.-._.--_ .. ---'
.-.-.-.-
I
,.....
~ 30
!3o
.....""
,/
~
,/
..<:
'0'"'
4-)
' ,/,/./
,/
'"
a-)
OJ
_
:=-----_..-.-"_.-.- -- - - - --::::"-. -
.---'/#
.....
..........
,/'
z>,<~./,/
2
-J
...:J
L_.....
..... "
20
/' ....
I
IV
N)
f-'
1
./
,/
10
10
o
['11
o0
10
10
20
30
40
50
60
70
70
80
80
Age
(months after release)
release)
Age (months
Figure 15.
15.
Figure
Fenced, Unfenced and Eelgrass
Eelgrass Covered
Covered
Growth Curve of Manila Littleneck Clams Planted in Fenced,
Areas of Netarts Bay,
Bay, 1974-81.
1974-81.
Areas
-22-
Table
Table 7.
SUllllMry
in
SuimonayofofTotal
Total NumberslJof
Numbersilof Marine
Marine Organisms
OrganismsOccurring
0 ocurringin
Commercially
Area 2, Yaquina
Yaquina
CommerciallyHarvested
HarvestedPlot
Plot CC and
andControl
Control of
of Area
Bay.
1981.
Bay, 1981.
5/n/81
5/11/81
Control
Plot CC
9/30/81
Plot
Plot CC
Control
0.9
0.0
4.6
39.3
30.3
I«JLLUSCA
I I US CA
CZ-&woardiwn. nuttaZ"Lii
CUnoeanffum
nuttailCi
Cryptonmjaaalifomiaa
cclifcr,aicc
Cryptomya
rccro inquinata
Saridomus
gigante-us
Scxid,nus gigweteua
H.zCOlrl'J.
'17'esU8
aapax
2'eeue caqax
Venarsq,is
Venerupis staminea
stair/nec
Pododesmus
6dadesmus macl'Osahi8ma
macroeahiema
Chiton
chiton
BfJnnissenda
ffeo,nissenda omssiCOl"rlis
cnzss/consis
NuaeUa
Nuceija 1-amelZosa
lwneilcea
Nudibranchi
Nudibraoschi
OnohideUa
&,cht'della borealis
Lrealis
Hinnites multirugoeus
multirugosUB
Ri,mites
TPiopha
Tar/epIc sp
Anaula pacifica
,4ncaia
par/f/ca
Onahidoris
O'aahidaris biZ-amelZ.ata.
bilamellata
0.1
0.0
7.4
4.8
4.8
2.6
2.9
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.2
0.3
24. :3
24.3
1.3
9.2
8.2
0.5
0,3
0.0
1.0
0.1
0.1
0.3
0.0
0.0
0.1
0.0
0.0
0.0
0.0
0.1
0.1
0.4
4.7
1.2
2.8
2.8
0.0
0.0
0.0
0.0
0.0
0.5
0.0
0.0
0.0
0.0
0.0
1.5
0.0
5.4
6.1
6.l
o. ,
0.8
0.1
0.1
0.0
0.1
1.3
0.1
0.1
0.0
0.0
0.0
ANNELIDA
MINELI
DA
Glyceridae
Glyceridam
Lumbrineridae
Lumbrinoridae
Nereidae
OphellHdae
Ophmlliidae
Orbiniidae
Orbinijdae
Pectinariidae
Phyllodoc:idae
Phyllodocidae
Polynoidae
Terebellidae
Terehel1idae
Capi
tellidae
Capitellidse
Cirratulidae
Cirratulidas
Nemertien worm
Nemertian
worm
11.1
11.1
0.0
0.0
6.3
0.1
0.3
2.7
2.7
0.1
9.4
0.0
0.2
4.6
0.1
1.1
0.0
3.4
1.6
4.4
0.9
0.0
2,5
2.S
0.2
0.1
4.3
0.0
5.8
5.8
0.0
0.2
1.3
0.0
0.4
0.2
0.0
0.0
0.0
4.4
4,4
0.3
0.0
0.4
0.1
0.0
1.0
0.1
0.7
0.7
3.4
0.0
0.9
0.1
0.0
0.2
0.2
0.0
1.8
0.0
0.0
1.8
1.8
0.0
0.1
3.8
0.0
0.1
0.0
0.6
4.9
0.0
0.0
0.0
0.0
0,1
0.0
0.1
0.0
7.2
1.2
0.0
0.0
0.0
0.1
0.2
1,0
1.0
0.1
4.1
0.5
0.0
0.2
4.2
0.3
0.3
0.2
0.3
0.4
0.2
0.1
6.6
0.0
0.0
0.0
0.0
6.3
6.3
0.1
0.0
0.0
0.1
0.1
0.0
0.0
0.0
0.3
0.3
0.3
0,3
1.4
1.4
1.4
ARnlROPODA
ARThROPODA
Cancel'
Cancertrngister
mag/ster
Cancer
Cancer oregonensis
ore goneneis
Canae:r>
Cancerproduot1J.S
pratctus
eallianassa
CatUanceacoo.Zifornifmsis
cal/fan/ens/a
Caprellidae
Caprellidam
Caridean shrimp
Garidean
shrilllp
Gall\!llarideall
Gamoatidean amphipods
Hemig:rapSUB
Eeso'Lgropsus01'sgonensis
oregonenais
L::>phopanopeus op
sp
Lophapsraopeus
Loavrlaynohus
L::>:ro1'hynchus ep
sp
Paguo'ua
PaflU1'U8 op
Elp
Petl'OHethes ci.aetipea
cine.tipea
Petroliethae
Pinni= ep
sp
Finn/mn
lJpOgebia
paagettensis
Logebia pugettenaiB
00
0.0
0.3
0,0
0.0
0.1
0.0
7.1
0.0
0.3
EUUNODEPM&TA
EQUNODERMA.TA
Amphiodia
AmphicdiaocaidJmta.Zis
occidentalia
Eva.sterias op
sp
Toaster/am
Ophiuroidae
crphiuroidae
Pycnopodia.
Pgcnapcdia heZianthoide.a
hetiwat800idea
2.1
0.3
5.3
'.3
OJELENTERATA
0)ELENThRATA
2.3
2.3
0,2
0.2
2.7
0.3
BRYOZOA
BRYOZOA
0.0
0.0
0.0
0.7
HYDROZOA
HY080ZOA
0.0
0.0
0.1
0.0
0.0
0.0
0.1
0.0
Pholidae
Pholidae (gannets)
(gunnels)
(blenny)
Stichaeidae (blenny)
Cottidae (sculpins)
(sculpinsJ
Cattidae
stigm;wua
atignaaeua
0.0
0.1
0.0
0.0
0.2
0.0
0.1
0.1
0.0
0.0
0.0
0.0
0.0
1.1
0.0
0.1
number of
of organIsms
organisms
Total number
653
Numberfft2
Number/ft2
54.5
750
62.5
664
66'
1195
99.6
Anthozoa
Msthozoa
EOlIUROlDEA
EQiIUROIDEA
£&echio anaqao
lh'eahia
=upo
VERTEBRATA
YE RTh ERATA
Cithariciothye
CitharichthY8
1/
!J
Numbers
Numbersare
are organisIllSfft
organisms/ft22
55.3
8.
Table 8.
SummaryofofNUllbers!/
Nuithersilof
of Representative
Representative Marine
SUIIIISIlry
Marine 0rganis
Organisms Occurring
Commercially Harvested
Area 2,
Oregon.
Occurring in Commercially
HarvestedPlot
Plot C
C and
and Control
Control of
of Area
2, Yaquina
Yaquina Bay.
Bay, Oregon,
1979-81.
3/13/79
3/13/79
Plot
C Control
Control
P1st C
US CA
MOLLUSCA
Cl.inocardium
Ciinocarditm,nuttatLii
nuttallU
Mzrn inquinata
/bOO"'"
inquinata
Sazi<t>1I1U8 gigan
tous
sazick'mue
giganteus
Trnun
aapax
Tl'6
BUS ""l"""
Ymwrupiu
Vnn.rupia staminea
staninca
0.4
0.4
4.3
1.9
0.0
1.2
1.2
5/24/ 79
5/24/79
11/6/79
11/6/79
Control Plot C
C Control
Control
Plot CC Control
0.3
0.3
DA1t
DA'lE
5/1/go
5/1/80
Plot CC Control
1.8
1.8
0.3
60.3
F
F
9/17/80
Plot CC Control
Plot
Control
6/9/81
Control Plot CC Control
Control
Plot CC Control
0.4
0.3
9.3
3.8
3.8
5.1
5.1
1.6
1.6
0.2
16.7
1.0
2.8
0.3
0.1
0.1
7.4
7.4
4.8
2.6
2.9
2.9
0.0
0.0
0.0
15.6
1.4
1.4
1.4
5.0
4.2
3.0
0.4
0.4
1.3
11.8
0.8
0.8
1.8
1.8
1.0
1.0
1.0
1.3
1.7
5.4
5.4
1.2
1.2
1.9
5 .4
5.4
4.2
4.2
0.4
0.4
0.0
OilS
015
1.0
0.2
0.3
0,0
0.0
0.2
0.2
0.9
0.2
0.2
0.1
0.1
0.0
0.0
0.0
56.6
56.6
2.8
2.8
12.2
0.8
3.3
3.3
0.9
12.3
0.8
0.5
0.5
102.5
102.5
1.0
6.0
0.5
0.5
0.0
0.0
3.7
3.7
4.4
4.4
0.0
0.0
1.3
1.3
0.4
333
33.3
3.5
3.5
9.6
9.6
0.5
0.5
42.0
42.0
4.1
4.1
s.;)
5.3
0.0
0.0
11.8
11.8
0.0
0.2
0.2
0.0
0.0
1.9
0.2
0,2
5.4
5,4
1.8
1.8
1.6
1.6
9/30/81
0.2
0.2
Oneway
Degrees
of
AnOya
Anon
Freedom
Freedom
1.3
1.3
9.2
•'0.3
0.3
0.9
0.9
4.6
4.7
l2
1.2
2.8
2.8
1.5
39.3
39.3
5.4
5.4
6.1
6.1
0.8
0.11
0.11
14.67
0.88
0.88
0.86
0.86
12.02
(l,12)
(1.12)
(l,12)
(1,12)
(l,12)
(1,12)
(1,12)
(1,12)
(1,12)
(1,12)
0.0
0.0
11.1
0.0
6.3
0.2
0.2
1.0
1.0
1.0
0.1
0.1
2.7
2.7
0.4
1.6
1.6
9.4
0.2
0.2
4.6
4.6
1.1
1.3
2.5
2.5
0.1
4.3
5.8
0..18
0.18
0.55
0.55
0.21
0.21
0.24
0.24
0.87
0.87
(1,12)
(1,12)
(l,12)
(1,12)
(1,12)
(1,12)
(1,12)
(1,12)
(1,12)
(1,12)
0.9
0.0
0.0
0.1
0.0
1.8
7.2
7.2
1.2
1.2
0.1
0.1
0.1
3.8
3.8
0.3
0.0
1.8
3.5
3.5
0.7
0.1
0.1
0.0
0.3
0.0
7.1
7.1
4.2
0.3
0.3
0.1
1.43
14.09
14.09
2.13
0.01
0.01
0.38
(1,12)
(1,12)
(1,12)
(1,12)
(1,12)
(1,12)
(1,12)
(1,12)
(1,12)
(1,12)
24.3
24.3
ANNELIDA
Capitellidae"
Capiteilidae
LUllbrineridae
Lurineridae
Ophelliidae
Orbiniidae
Orbinjidae
Phyllodocldae
Phyllodocidae
0.0
0.4
0.4
0.0
0.0
0.0
0.0
>10.0
'10.0
>10.0
0.0
>10.0
0.3
0.0
0.0
0.0
>10.0
>10.0
>10.0
>10.0
>10.0
0.0
0.0
4.5
4.5
>10.0
O.S
0.S
>10.0
0.5
2.0
0.0
0.0
11.3
..3
0.0
0.0
0.0
0.0
ARniROPODA
ARTh)P0DA
0.0
0.0
0,1
0.1
0.1
0,1
>10.0
0.0
0.0
1.8
1.8
0.5
0.3
1.9
1.9
0.0
COELENTERATA
cDELENTEMTA
Anthozoa
Anthozoa anelOne
anewne
0.5
0.5
0.0
0.3
0.0
0.0
1.8
0.0
0.4
0.4
0.3
0.4
0.1
2.3
0.2
0.2
2.7
0.3
7.40
7.40
(1,12)
(1,12)
EOllNOIERMATA
EO1IN0R14ATA
Ophiuroidea
hstiwsthoidas
l'ti-rodia
Pyowpodia heUanthoidJl.
0.8
0.0
1.4
1.4
1.6
1.6
1.6
1.6
0.0
3.0
3.0
0.0
2.3
0.3
2.8
0.2
2,1
2.1
0.3
5.1
0.4
8.6
8.6
0.2
13.2
0.3
6.6
6.6
0.0
6.3
0.1
0.1
2.1
2.1
0.3
8.3
8.3
1.47
2.70
(1,12)
(1,12)
(l,12)
(1,12)
Not
16.7
calculated
64.7
64.7
76.3
99.6
99.6
48.0
51.3
45.3
57.4
44.9
44.9
89.1
89.1
cancal" produatus
CmWaP
produotus
G
....ride an ,""",i
pods
Gammerideat
ançhipods
HemigropSU8
HemigrapsueONgonensU
oregonensis
Pagurus op
op
Pagurua
rpoll"bia pUJ16tten.i.
(ipogebia
pugettensie
1.5
1.5
Total Nwrber/ft2
Nudler/ft 2
0.2
0.2
Not
areorganisms/fti'
organisms/ftY
Nutrs are
!J/ Numbers
Critical FF value
value' 4.75
4.75
4.4
calculated
calculated
0.5
0.5
0.2
0.2
0.0
4.1
4.1
0.5
1.4
1.4
I
IV
'"
I