CLAM RESOURCES IN A PROPOSED CHARLESTON
BOAT BASIN EXPANSION SITE
by Tom Gaumer INFORMATION REPORT 78-1 Oregon Department of Fish and \<Ji1dlife January 1978 .\
CLAM RESOURCES IN A PROPOSED CHARLESTON BOAT BASIN EXPANSION SITE
INTRODUCTION
The Port of Coos Bay is considering expanding their marina facilities
in Charleston.
Several sites are being considered; one to the north of
the present boat basin and one to the south (Figure 1).
The southern
proposal is for an area that historically has supported an important
recreational clam fishery.
A Fish Commission of Oregon resource use survey
of that tidef1at in 1971 showed that 974 clam digging trips representing
1,603 hours of effort were made to harvest nearly 20,000 clams (Table 1).
Cockle, gaper and littleneck clams were the principal species collected.
Because of the importance of this tideflat to recreationa 1 clam diggers.
we conducted a biological inventory of the clam flat during July 1977.
Results of this survey are presented in this report.
Table 1. Number of Digger Trips, Hours of Effort and Clams Harvested
in South Slough at Coos Bay in 1971.
Boat
Bas'j n
Char-' eston
Flat
Ti deflat
South
Slough
Peterson1s
Flat
Tota 1
~o. Digger Trips
974
2,233
1.043
156
4,406
No. Digger Hours
1,603
3,656
1,701
264
7,224
i
No. Clams Harvested
.t;l,
Cockle
9,690
14,310
7,663
221
31,884
Gaper
5.145
7,120
5,248
736
18,249
Littl eneck
4,041
3,799
46
88
7,974
844
1,005
2,080
44
3,973
a
935
371
113
654
0
19 833
27 823
15 408
Butter
Softshell
Bentnose
Tota 1
°0
089
1,306
767
64 153
Fossil
Proposed
1/
ir=Poinf
IIII
/I
I
I
.J• ,
,
,, .
fl: i--;~c-"::: J
,,
I
(f l~~~;,jq
,
,
-\
:
'
"
\
=J
,,_~-,,-c.
~_=,
~~~,- ;' ~_,(_..::::', '
--I
__
,!,
lj
If
,
,C::-,
lA'
iii)
it
,hi
l
' _ -" - , .
,.
_,
"
J'
I
l,'
I "
.
! ;f
r
,,~'
,~"."
\\ I
b
,/:?-,
'. .\
/,
:
I
{
'(i !
"
L~ ,~ /'
/
I
1
N't
I
rn'. ,
I
f"
,/
. ., - ' - - " - ­
,."
';'II
I
"
I!'
,/
,,'
t ;
.' I I,'
\
i\
./'j'
,
''
';
".'
"
"
''(.I'"
I!
1\
i: '.......',.,...
'-l~r#;:7 ,
;I'
Figure 1.
I I'
,liS
"
\1;,
I
<
:&'~, »:::::::;.,: A'~J~
'I
t : ~ ,~;
,
'
~
'
:
,
~
~ ...c:\\',
'~'
,'.
'\
'I
:
f""
" .'
t-A~.
0
/ ". , , :
~
"';!b
'. 'Ii en
a ~~\
~ r~O..., /I"
: ~.
, . 1f
//
r
I
, f """'"
.'-­
/ , , - ­
'~
I
, .
i "
' l"j
J
"
"l';:=:-::://
.
:
I'
"
1-'-­
;/
/ ' #'
;?-,'
P'
Qf.- 't::"Y ,d
\\,
1
L-o I,
..y
-.:
Proposed Construction Sites for Expansion of Charleston Boat Basin
,
if
All~
/,/
I
h~"
",,-,,~,9--='
~/
<:;:"..."
; , . ', ( /
'!
,,
/ / ' ; '
I
I
\ ' '-£JuJ~ Barview
II
-,J
:::;:t.
,--'
•
'
'.
'"
N
('
-3­
Methods
Standard transects were established across the 11.5 acre (4.7 ha)
tidef1at {Figure 2}.
to each other.
Transects were 150 feet (45.7 tn) apart and parallel
Sample stations were 100 feet (30.5 m) apart along each
transect line.
Samples were taken by ODFW scuba divers using a 6-inch (15.2 cm)
suction pump that was fitted with a 1/2-inch {1.3 cm} mesh wire basket.
Each 2ft2 (0.2 m2 ) sample was excavated
Forty-nine samples were collected.
to a depth of approximately 12 to 18 inches {30.5 to 45.7 cm} or until the
opera tor was confi dent an clams had been removed.
A11 reta i ned pump
material was emptied from the basket and sorted in the boat.
All clams
obtained were saved and taken to the laboratory where the gaper, butter,
cockle and littleneck clams were measured, weighed and aged.
Length
measurements (in mm) were taken from all clams except the cockle where
height (rib length) was used.
gram.
All clams were weighed to the nearest lower
The clams were weighed alive.
Gaper clams were aged by counting the
annual growth rings in the ligament scar.
Butter~
cockle and littleneck
clams were aged by counting the annual rings on the exterior surface of
the shell.
Results
Figure 2 shows the occurence and distribution of clams in the proposed
South Slough marina site.
Two different observed concentrations of clams
per sample are illustrated; those with less than two clams/square foot
(0.092 m2 ) and those with more than two clams/square foot.
Nine species of clams were recorded from the area.
Tresus capax, cockle
CZinocard~iwn
Five species, gaper
nuttallii. native littleneck Venerupis
-4­
COOS BAY i
AI
t~
II
QiI\Rl£STON
TOTAL CLAMS
Dens i ty 0:: 0.5 - 2/ft2 .:: >2/ft2 Scale
(ft)
+-_.+---+--..........- - · - - 4 .
o
5.:):) ,
ICO 0
Fi gure 2.
SOUTH SLOOOi
C1 am Survey Project Area J South Slough of Coos Bay, 1977
-5­
{It.aminea,
butter SaxIdomuH
uiuanteu[J,
Y'outinely dug by clam diggers.
and softshell clam
Mya ar'enaria
The other four species, irus
piddock Z1:rfaea piZsbl""yi. bentnose
,\1atJoma
are
Macoma irus.
nasuta. and jackknife clam Solen
sica2'ius, although not generally taken by clam diggers, are important
biologically to the estuary.
The distribution and relative abundance of
each of the nine species of clams are shown in Figures 3-11.
We estimate that 10.1 million clams inhabited the area (Table 2). Of
this total, 6.4 million were irus clams, 1.5 million were bentnose and 1.3
million were gaper clams.
The 95% confidence limits for gaper clams were
663,600-1,998,200.
Age compositions of butter, cockle, gaper and littleneck clams are
shown in Figure 12.
Except for the littleneck clam. spawning or survival
of set appears to be sporadic.
Irregular spawning or survival of clam set
has also been noted on other subtidal clam beds in Coos, Tillamook and
Yaquina bays.
Biomass estimates were calculated for butter, cockle, gaper and littleneck clams and totaled 502,200 pounds (227.8 m.t.).
442,500 pounds (200.7 m.t.) of the total.
Gaper clams comprised
Gapers averaged 0.34 pounds
(153.0 grams) each.
The length frequency for gaper clams is shown in Figure 13.
of gaper clams was 83.1 mm (3.27 in.).
Mean size
Size composition for butter. cockle
4'.~.
and littleneck clams is not shown due to the smail numbers taken.
-6­
Table 2.
Summary of Numbers of Clams, South Slough Proposed Marina Site,
Coos Bay, 1977.
Species
Number Irus ..•....................................... 6,427,000 Bentnose ...................................... 1,482,000 Ga per ..... "........................................ 1 ,333, 000 Coc k1e ..... ".. " " . " "........................ "... "..... 348 , 000 Native littleneck ............................... 289,000 Butter ............ "........... "" ..
Softshel1 .
II
•••
"
•••
10
•••
".""
••
"
•••
119,000 * •• , • • • • • • • • • • • • • • • • • • • • • • • ". ""
50,000
Jackknife ........................................ 20,000 Piddock .......................................... 10,000 Tota] ........................................ 10,078,000 -.'
-7­
COOs HAY
J
t--
/
r"'''"..;'
/
I
I
CHARL£STON
GAPER CLAM
)
Densfty
0=
0.5 - 2/ft 2
•
>2/ft2
=
/
/
Scale
( ft)
"ofl'tl
o
5~;
Ffgure 3.
-I,
SOUTH SLOI)JH
1000
Clam Survey Project Area, South Slough of Coos Bay, 1977
/
-8­
COOS BAY
/
Q1ARLESTON
COCKLE CLAM
Density
o = 0.5
I
- 2/ft2
• = >2/ft2
SOUTH SLOUGH
Scale
( ft)
~.-+t~'-'~I~.-------~I
()
5(.);) ,
Figure 40
f
100 ()
Clam Survey Project Area, South Slough of Coos Bay, 1977
-9­
roes
H4Y
/
}
I
j
• I
O1AAlESTON
NATIVE LITTLENECK
CLAM
Densi ty 0::: 0.5 - 2/ft2 e=
/
I"~
2/ft 2
Scale
( ft)
+---f-~-t-,.
.. - - - ' " - - - f
(')
SGb;
(
.
I
1(;;00
I
I
I
I
Fi gure 5.
C1 am 5urvey Project Area. South 51 ugh Of Coos Bay. 1977
0
/
I
I
-10­
CCX>s BAY
(
j
I
I
f
./
I
OiARLESTON
BUTTER CLAM
Dens j ty
0= 0.5 - 2/ft 2
.::: >2/fF
SC(lle
( ft)
+-I---'~-f-.-t-+--------f ,
C.
Sa:> '
IDO 0
Figure 6,
SOlm-l SLOIXJ;
Clam Survey PrOject Area. South Slough of Coos Bay. 1977
./
/
\
I
-71­
OJos BAY
f
(
\
}
/
/
/'
,
r"
' f1
(
SOFTSH£Ll CLAM
Density
0= 0.5 - 2/ft2
Sca1e
( ft)
*'"--+.'--.......~. ""TI-,~--...
()
Sec
T""'t
Fj gure 7"
. . ­- --f
,
//;>00
Cl om Survey Projec t Area. Sou th Slough
0
f Coos Bay. 1977 .,,) ,
., /'
[
/
I
A
I
r
-12­
I
cOos BAY
j
j
j
j
j
(
,
j
,I
I
j
\
j
!
-
-­
j
/
/
j
j
j
j
j
CHARLEST(~
j
j
j
IRUS CLAM
')
Densi ty
0= 0.5 - 2/ft 2
•
=
j
>2/ft 2
Scale
( ft)
/
/
/
j
j
j
I
j
j
j
j
l
I
j
j
j
j
j
j
Figure 1\
Cl a" SUrvey Proj ec t A,,,, ,1, Sou th Slough
0i
Coos Bay, 19 n
j
j
j
-13­
COOS BAY (
l
I
(
\
,1
I
~,
\
''\Ii,'--~---
-'
I
-----OiARLESTON
BENTNOSE
CLAi~
Densi ty
0== 0.5 - 2/ft2
•
==
2/ft2
{
J
I
~;)Ul1-1
Scale
(ft)
SLOlJ(l,
t -.... - 4 - - 1 -..- . - -..- -.. "~ • D
Sa?
/",o0 I
Fi gure 9,
Clom Survey Project
J\I~ea,
Scuth S10ugh of Coos Bay, 1977
,.I
,I
.
-14­
COOs BAY
---­
./
I
(~
--Il
CHARLESTON
lIt j
jt t
PIDDOCK CLAM
Density
i
0:: 0.5 - 2/ft 2
1
t
4
'-...
-f
tIl j 1
j
Scale
( ft)
~+~'~'~f~I~·~--__~4 .
o
~.
F1 gu re 10.
I~OO
/
./
sOUTH SLOLG;
l
C am Survey Project Area. SOuth SI Gugh 0 f Coos Bay. 1977
/
/
)
/
/
-15­
OOOs BAY
.--"
/
CHARLES TC:X-J
T
JACKKNIFE CLAM
DenSity
o = O. 5 -
+0
,
2/ ft 2
..,.
/i 1
~l
t
~
Scale
1
t
I
(
i
t
i
1
(tt)
Sa;'
Fi 9ure IL
-I,
lOOt)
C) am Survey PrOjec t Area. South S) ough
0
f Coos Say. 1977
/
/
/
I
J
~
A..
-16­
50 Li ttl eneck Clam
N=29
40 30 20 10 0...­
rI
0
I
Gaper Clam
N=134
40 -
30 20 10 OJ
0'1
ctI
+-'
0
Cockl e C1 am
N=35
s::
OJ
u
~
60 OJ
0...
50 40 30 20 10 0
Butter Clam
N=12
r--"'"
30 -1.
20 10 l0
77
76
Figure 12.
75 74 73 72
Year Class
71
70
I I
69
68
Age Composition of Clams, South Slough
Marina Site, Coos Bay, 1977.
2q~------------------------------------------------------------~
Gaper Clam N=131
X=83.1rrm
1
Q)
t:T
~
+-l
t::
CIJ
U
s..
11
r
•
Q)
0-­
_I....
\
"'"
I
5
a
o
j
.c 10
>-.L
20
"">..C
30
).
40
50
60
70
80
90
100
110
120
130
Size (rrm)
Figure 13. Length FreQuency of Gaper Clams. South Slouqh Marina
Site. Coos Bay. 1977.
140
150
160
-18... DISCUSSION Our observations on the clam resources of the proposed South Slough
marina site substantiates the fact that this area is not only an important
component to the overall clam stocks of South Slough but is also a valuable
resource to the recreational clam digger in Coos Bay and Charleston.
Although South Slough has substantial clam resources both intertidally
and subtida11y, limited shore access has always been a problem.
In the
1971 resource use survey of Coos Bay, only four areas on South Slough were
easily reached from shore.
In numbers of clams harvested, the proposed
marina site ranked second in production to the "Charleston" clam bed above
the Charleston bridge on the west shore.
Since 1971, reduced parking, due
to new industrial development, and restricted access to the "Charleston
ll
clam bed has substantially increased the importance of the proposed marina
site to recreational clam diggers.
Although much of Coos Bay and South Slough remains to be surveyed, it
seems reasonable that other areas of the bay should be considered as alter­
native sites for development.
the existing boat basin.
One of these areas ;s immediately north of
This area has been suggested for development for
some time and although the tidef1at has not been surveyed for clams,
historically this area has supported only an
i~cidental
razor clam fishery.
It therefore seems appropriate that the proposed South Slough marina
site be preserved as a clam producing area and that any further development
or encroachment into that area be strongly opposed by our agency.