STATUS
STATUS OF
OF STOCKS
STOCKS
A.
Clams
Bay Clams
1.
Stock status
1. Stock
status
Adequacy of data base
base
2. Adequacy
3. Management issues
issues
B.
Bait Shrimp
Shrimp
Stock status
status
Stock
Adequacy of data base
base
2. Adequacy
issues
3. Management issues
1.
1.
C.
Appendix
Figures 1-18
1-18
Oregon
Department of
of Fish
Fish & Wildlife
Wildlife
Oregon Department
Marine
Region
Marine Region
March
1990
March 1990
,~
Clam, Bait Shrimp,
Shrimp, Estuary
Estuary Habitat
Bay Clam,
OP STOCKS-BAY
STATUS OF
STOCKS-BAY CLAMS
CLAMS
Recreational clam diggers continue
continue to
to enjoy
enjoy good
good
digging for
for bay
bay clams.
clams. Catch per effort (CPUE)
(CPUE) data
clams/trip or
or 11.8
11.8 clams/hour
revealed diggers averaged 17.2
17.2 clams/trip
1975, only during
Since 1975,
during four
four other
other years
years have
have clam
clam
in 1989.
diggers enjoyed
enjoyed better
better digging
digging rates.
rates. Cockle
Cockle clams
clams continue
to be the most popular species
species dug,
dug, comprising
comprising nearly
nearly 27%
27% of
of
the total harvest.
commercial
clam diggers harvested 44,696 lb
Ib in
in
Commercial bay clam
1988,
production since
since 1975
1975 when 26,550
26,550 lb
Ib were
were
1988, the lowest production
reported.
Final landings for 1989
1989 are unavailable but it
it
similar to 1988.
1988. Poor
Poor recruitment
recruitment
looks like the harvest was similar
of the gaper clam since 1975 has
has reduced
reduced the
the availability
availability of
of
gapers in
in several
several popular
popular digging
digging areas.
areas. Because of the
poor recruitment,
recruitment, we discontinued issuing
issuing mechanical
mechanical harvest
harvest
permits in
in 1985.
1985. Only hand harvest has been allowed since
then.
In 1988,
1988, we issued
issued 136 permits to commercial
fishermen to dig clams.
clams. Cockle clams comprised 67% (30,068
(30,068
Ib)
harvest. Seventy-seven percent of the
lb) of the total harvest.
total production was taken subtidally
subtidally from
from Tillamook
Tillamook Bay.
Bay.
Subtidal stock assessment surveys
surveys in
in Nehalem,
Nehalem,
Tillamook,
Yaquina, and
and Coos
Coos bays
bays have revealed that
that most
most
Tillamook, Yaquina,
clam stocks are
are in
in aa healthy
healthy condition.
condition. Only the status of
the gaper clam is in question with
with the
the poor
poor recruitment
recruitment
1975. Population estimates for gaper clams in
in Yaquina
since 1975.
from 36.3
36.3 million
million in
in 1975
1975 to 7.4
7.4 million
million
Bay have declined from
in 1988.
Since the 1960's we have introduced
introduced Manila
Manila littleneck
littleneck
into several
several of
of our
our estuaries.
estuaries. Our goal was to
clams into
develop spawning populations
populations of
of Manila clams.
clams. To date,
date, we
have released an estimated 3.6 milliom clam
clam set
set and
and nearly
nearly
92,000 adult clams.
clams. Most of these clams were donated to our
our
project by
by private
private industry.
industry. Over the years we have
conducted numerous experiments utilizing
utilizing plastic
plastic netting
netting and
and
various introduced substrate
substrate types
types to
to improve
improve survival
survival
rates.
ADEQUACY OF DATA BASE-BAY CLAMS
Our data base for bay clans
clams comes
interviewing
comes from
from.interviewing
clam diggers
diggers on
on 22
22 major clam
clam beds
beds in
in 88
recreational clam
Each year we collect biological data from
from
estuaries.
approximately 1,400
1,400 diggers.
diggers. Data includes CPUE,
CPUE, digger
approximately
origin, and
and species
species and
and size
size composition.
composition. We attempt to
origin,
measure 200 clams
clams of
of each
each species
species from
from each
each clam
clam bed.
bed.
Biological data collected from
from commercial fishermen
fishermen
includes size composition
composition by
by species.
species. Logbook data provides
information on CPUE and species composition and is also
also used
to
fish ticket
to reconcile and error check differences on fish
landing reports.
reports.
and biomass estimates,
estimates, and size and
Annual population and
age
species, have been collected in Yaquina
age composition by species,
Bay since
since 1975.
1975. In 1989,
1989, time commitments
commitments precluded
precluded us
us from
this survey.
survey. Future
Future surveys
surveys in Yaquina Bay will
doing this
depend on staff having the time or there is aa change in our
conduct these
these
priorities. Because of the time required to conduct
types
studies, we discontinued our surveys in the other
types of studies,
bays in
in 1985.
1985.
observations revealed
revealed successful recruitment has
Recent observations
occurred in Netarts Bay with adult Manila clams
found in
clams found
several locations. Annual monitoring of Manila
Manila clam plants
revealed survival as high as
as 83%,
83%, three
three years
years after
after release,
release,
was realized
realized with
with the
the application
application of
of plastic
plastic netting.
netting.
Testing of survival of Manila's in various sUbstrate
substrate types
types
revealed that mixtures of ground oyster shell
shell and pea gravel
significantly higher survival than the other
produced a significantly
tested materials.
MANAGEMENT ISSUES-BAY CLAMS
Two issues concern us;
us; the poor recruitment of the
the
gaper clam and the encroachment of ghost and mud
mud shrimp on
clam beds.
STATUS OF STOCKS-BAIT SHRIMP
In
In 1988,
1988, we
we issued 149
149 permits
permits to
to commercial
commercial bait
bait
shrimp fishermen.
fishermen. These fishermen landed 109,784 lb
lb (69,507
(69,507
lb were ghost shrimp,
shrimp, and
and 40,277
40,277 lb
lb were
were mud
mud shrimp).
shrimp). Peak
year of harvest was in
in 1986
1986 when
when 128,600
128,600 lb
lb were
were reported.
reported.
Our field studies have revealed that both species have
proliferated during the past several years and today several
important clam beds have nearly been destroyed
destroyed by their
presence.
ADEQUACY OF DATA BASE-BAIT SHRIMP
commercial harvest of
During the year we monitor the commercial
fishermen. Data are collected on size composition
composition
shrimp fishermen.
for each species.
species. Logbook data are also collected giving
giving us
us
CPUE information for
for each
each fisherman
fisherman and
and harvest
harvest method.
method.
MANAGEMENT ISSUES-BAIT
ISSUES-BAIT SHRIMP
SHRIMP
MABAGEMENT
Our main concern is the expansion of shrimp on clam
beds.
beds,
I[iTI
60
80
fz
Z
W
Ui
60
6O
C
(.)
0::
W
C.
0Q
SOFTSHELL
SOFTSHELJ-.
G
EI
I1l3
11II
LITTLENECK
LflTLENECK
G,APER
GAPER
caE
=<LE
BlJITER
BUTTER
40
20
(
a
El
197519761977197819791.980
197519761977 1978 1979 1980198119821983198419851986198719881989
1981 I 98219831984 1985l986198719881989
YEAR
recreational harvest in
Figure
1. Species composition for
for recreational
in
Figure 1.
Oregon,
(all bays combined),
combined), 1975-89.
1975-89.
Oregon, (all
(
100
100 -,.--.",
80
I6060
IZ
z
W
Lii
C,)
0
a:
W
a.
40
40
llJ1
NON·STATE
NON-STATE
BlI
IN-ST
ATE
N-STATE
11II
LOCAL
20
o
0
197519761977197819791980198119821983198419851986198719881989
I
975 1976 1977 1978 19791980 19811982 19831984 198$ 1986 19871988 1989
YEAR
Figure
recreational clam diggers
Figure 2.
2. Area of residency for
for recreational
in
(all bays
bays combined),
combined), 1976-89.
1976-89.
in oregon,
Oregon, (all
30 - , - - -. . .-----------------------~
C-- CLAMS/TRIP
CLAMSfTRIP
~
*-* CLAMS/HR
CLAMS/HR
tl.
a.
20
0:0:
I-:I:
<ncn
(0(/)
:::E:::E
<C
««
..J..J
-i-i
uu
00
10
0+-----r--r--r---r--r--r-...,--r-...,--.---,...-~~-~___1
ci
I
I
I
I
I
I
I
I
I
I
1974197519761977
1974
1975 1976 1977 1978
1976 1979
1979 1980
1960 1981198219831984198519861987198819891990
1961 19621983 1984 1985 1986 1987 1966 1989 1990
YEAR
unit of
of effort
effort for
for recreational
recreational harvest
harvest
Figure 3.
Figure
3. Catch per unit
(all species
species combined),
combined), 1975-89.
1975-89.
Oregon, (all
in oregon,
120
100
n1
80
.- '"
~
E
-
E
§.
60
uJ
Lu
N
!::!
en
_'"
• • "'~.
Jr
'" '"
a--
40
-0--
...
A
BUTTER
CCOQE
=<I.E
-t GAPER
• Gi'PER
20
0
1974
...
1976
1978
1980
1982
1984
--frA--II
a---
SOFTSHB.L
SOFTSHELJ..
1986
1988
LIrn..ENECK
LITTLENECK
199,0
199.0
YEAR
Figure
size composition of recreationally
recreationally harvested
harvested
Figure 4. Size
clams in
in Oregon,
oregon, (all
1975-89.
(all bays
bays combined),
combined), 1975-89.
RECREATIONAL HARVEST
CLAMS
RECREATIONAL
HARVEST OF
OF GAPER CLAMS
12~,--==~-------_...:.......--
12
a
10
0.
-I
8
tr:
cc
I-
(U)
f)
::;;
<>:
-J
..J
0C-)
6 -
e HAPPY
- - HAPPY
CAMP
(Netarts)
s--CAMP
(Netarts)
--+.-
4
BRIDGE BED (Yaquiria)
(Yaquina)
....---U-
2~
1974
2+-
•
J
. 1976
I
,
1978
i
,
I
1980
j
BREAKWATER (Yaquina)
J
1982
i
J
1984
i
J
1986
I
i i i
1988
I
1990
YEAR
Figure 5.
5. Catch per
per unit
unit of
of effort
effort for
for recreational
recreational harvest
of
of gaper
gaper clams in three major clam beds,
beds, 1975-89.
1975-89
Table
7.
Table 7.
1975-88_
Peak clam
clam digger
digger counts
countsonontirieflats,
tideflats, 1975-88.
Peak
.. __ .... --- ............. - ............ - .... _.............. _- .... - ............ _.......... - ...
1988
1975 1976
1976 1977
1977 1978
1978 1979
1979 1980
1980 1981
1981 1982
1982 1983
1983 1984
1984 1985
1985 1986
1986 1987
1987 1988
1975
................. _........................ - .......................................... _--._Tillamook
Tilt amook
Garibaldi
Bay
Ocean
Bayocean
Netarts
Netarts
Happy Canp
CafTl)
Yaquina
Yaqui na
Bridge Bed
Breakwater
Idaho Flat
Flat
Idaho
Gas
Plant
Gas Plant
Coquille Point
Sally's
Sally's Bend
Alsea
Al sea
Breakwater
Bay Shore
North
Bank
NorthBank
Siuslaw
Sius law
North
North ·Forl<.
Fork
Coos
Coos
Charleston Triangle
Triangle
Charleston
Charleston Flat
Flat
Charleston
Peterson I s Flat
Flat
Peterson's
Pigeon
Pigeon Point
Point
North Spit
Spit
North
Clam Island
Island
300 460
460 516
487 350
350 118
118 380
380 400
400 257
425
350 131
225
516 487
625 350
131
225 256
256 300
280 122 39
107
4
0017
17
39107
4
33 13 10
33
-280122
-
-331310
-
-
175
175
73
-
245
245 138
138
127
127 120
120
110
98
110
98
30
30
62
62
45
45
-
-
-
-
-
-
-
-
-
159
159
67
67
14
14
425
160
160 425
150
150
91
91
23
23
66
24
24
17
17
41
41
-
-
-
-
-
-
-
-
-
-
-
-
55
55
-
-
109
109
-
-
76
76
-
-
138
138
-
-
-
35
35
-
-
-
112
112
-
-
-
322
322
-
-
-
116
116
107 204
206 225
84
84 107
225 110
110
30 46
46 17
17
28
25 30
28
25
39
39
35
31
50
56
35
31
50
56
34 20
20
10
10 11
10
11
34
10
77
4
14
4
5
9 14
5
9
48 27
27 14
14
15
15 20
20 48
3
3
4
4
15
15
13
13
45
45
44
44
18
18
33
33
22
22
43
43
41
41
44
44
56
56
45
45
41
41
26
26
2
2
42
42
39
39
87
27
27
66
82
82
103
103
4
4
52
52
102
102
93
93
57
57 146
146
-
-
265
265
22
22
10
10
00
-
-
-
314
314
22
22
20
20
5
5
31
31
-
-
191
191
00
14
14
00
12
12
49
49
4
4
-
-
-
478
478 200
200
625 275
84
84 225
225 625
275
20
20 27
27 63
63 26
26
61
38
46
61
38 176
176
46
26
26
41
16
12
41
16
12
18
18
55 41
20
41
20
44
44
46
57
57 32
32
-
-
500
500
9
9
-
-
-
31
31
24
24
-
-
-
64
64
30
30
-
-
-
-
5
5
-
-
-
-
62
62
-
-
-
-
-
-
-
-
-
-
-
-
50
50
37
58
58
-
-
15
15
14
14
97
83
158
83 158
86 119
86
119
67
67
.......... - ... -- ... -- .......... __ ........ _........... -............. _-._.- ...... _.. - ... _...
Fi
Figure
gure 6.
6.
c--------------~---------------------I'
400
DI -,
I
A
-0--
0;-0
t
~NDSI
DIGGERS
300
300
cC
0
'"
"'0o"
Ct
-C
.J::
;::.
Ul ~
Ow
ZCJ
:>CJ
0_
200
200
zw
0..0
fl-c
100
100
I
O -t--o
1940
,
,
1950
i
i
i
1960
I
1970
•
!
[
I
i
1980
YEAR
Figure 7.
Figure
7.
1941-88.
1941-88,
landings of
of bay
bay clams
clams in
in Oregon,
oregon,
Commercial landings
I
1990
80
1
6(
60
I
Wj
1976
1976
N
< 2129
11=2129
I
1980
11=297
N'
297
@
@
:P
I
1984
1984
N'
136
11=136
41
40
20
2'
___
It
In
__________________
_____ ___________
wm
,@
0
1977
N
< III
11I1I
60
6'
1981
1981
11=47
N'
47
1985
N < 180
11=180
'fu
40
4'
__
20
;F- 2'
Z
z
w
LU
(-3
U
cc.
a:
w
LU
0..
0
1978
1982
1982
1986
N
< 100
11=100
N' 271
N271
N' 285
11=285
60
6'
I
4J
4
"h
20
1979
_____ _
1987
1983
11=100
N'
100
11 < 312
11=312
60
Cl
S
JUL
JIlL
0
~
N
138
N'< 138
m
~;
4J
10
0)
I
"",mMWll1llffJlillIfiil
811
~
00)
/8
~
~
/8
M
/4
n
[11
YEAR-CLASS
YEAR~ClA5S
/0
m
I
00
Ca
88
ffi
84
M
WHi}})
~
82
00
80
m
78
76
74
72
70
68
53
66
64
82
~
YEAR-CLASS
Figure
Figure 8.
8. Age composition of
of commercial
commercial subtidal
clam
subtidal gaper
gaper clam
harvest,
harvest, Coos
Coos Bay,
Bay, 1976-87.
1976-87.
00
80
13
78
~
76
74
72
7?
YEAR-CLASS
m
70
~
60
~
(.6
6·;
6'
1400
1200
-0-I---s--
CPUEiTrip
CPUE/Trip - mechanical
-0--
CPU
ElHour ~- mechanical
CPUEJHour
IIII
•
1000
ibII
If)
CPUE/Trip
- hand
CPUEiTrip
- hand
CPUElHour -- hand
hand
CPUE/Hour
800
C
Z
:::J
0
c..
600
400
200
•
0I
0
1974
1976
1978
1980
1982
1984
•
1986
.
..
1988
YEAR
YEAR
Figure 99.
Figure
unit of
of effort
effort for
for conunercially
commercially
Catch per unit
harvested gaper
gaper clans
clams in
in Coos
Coos Bay,
Bay, 1975-88.
1975-88,
-
1990
1
150 5 0 , - - - - - - - - - - - - - - - - - - - - - - - - - ,
140
E
.5-
130
=
:I:
II-
(!l
a
w
Z
120
Lii
J
...J
110
100
+----r-~__,---,--,..._~-...,_--_r-~__,----l
100!
1974
1978
1980
1984
1986
1988
1976
1982
a
a
I
YEAR
Figure 10,
Figure
10. Size composition of
of connuercially
commercially harvested
harvested gaper
clams in
in Coos
Coos Bay,
Bay, 1976-87.
1976-87.
'00
100
1988
1985
Ii
N :: 112
112
1984
1994
N =
::: 140
140
80
60
60
'0
40
'0
..,
20
20
00
80
SC
1983
1903
N ::: 191
N191
1987
N ::: 104
1982
*982
1986
N
N :: 118
118
N ::: 149
149
N
N104
St
'0
40
4C
.
W
20
2t
"....
Z
0
W
Lu
()
C)
a:
w
Q.
0-
80
SI
'0
40
,.
20
21
_________
-
0
1965
198$
1981
1981
N ::: 162
N162
N310
N ::: 370
80
$
_I
6
'0
4
'0
20
2
0
68
1966 88
70
72
72
74
76
78
76
80
60
YEAR·CLASS
YEAR-CLASS
n
82
82
84
64
86
88
88
88
90
196668
90 1966
68
70
72
74
76
76
76
80
82
ö
84
a
86
ob
88
oo
YEAR·CLASS
YEAR-CLASS
Figure
Yaquina Bay,
Bay, 1981-1988.
1981-1988.
Figure 1.1 Age
Age composition
composition of
of subtidal
subtidal gaper
gaper clams,
clams, Area
Area 2, Yaquina
90
j30
130
GAPER
GAPER CLAM
CLAM RECRUITMENT
30
30
Ii:N
UJ
Ui
0:
m
<t
4
::l
a
-
-a--
l' J
I •
NETARTS
YAQUINA
YAQUINA BAY
25
25
20
20
(/)
(a
((I)
/)
:;;
<t
C
-J
15
-'
U
C-)
10
5
0
1974
1976
1978
1980
1982
1984
1986
1988
YEAR
Figure
Figure 12.
12. Recruitment of gaper clams in
in Netarts and
bays, 1975-89.
Yaquina bays,
1975-89.
1990
Table 8.
Table
Year
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
and bicmass
biomass estimates
(95% ct)
for gaper
gaper clams
clams in
inYaquina
Yaquina Bay,
Bay, 1975-88.
1975 88.
Population and
estimates (95%
CI) for
M
Estimates
Population Estimates
No.
%
Z
+-56
•.1
+-56.,1
+-51.5
+-44.5
+·48.9
+-48.9
+-51.7
+-51.6
+-49.4
6,320,000
6,320,000 +-42.6
.-426
7,680,000 +-40.3
5,600,000 +-59.2
4-32.6
6,480,000 +-32.6
5,920,000 +-48.8
-48.8
7,563,600 +-66.1
7,467,000 +-35.5
36,302,000
25,566,400
29,316,000
10,560,000
11,116,700
11,050,000
6,160,000
Biomass Estimates
Biomass
No.
%
5,084,200
5,217,200
4,969,000
4,136,800
3,459,900
4,252,500
2,569,700
4,424,900
5,042,100
3,528,700
4,708,200
4,350,600
6,507,400
7,430,500
Figure 13.
13.
Figure
N/A
N/A
N/A
H/A
N/A
+-39.0
+-33.2
+-33,2
+-36.9
+.36.9
+-30.4
+-29.7
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Multiple comparisons,
comparisons, Manila
Manila littleneck
littleneck clams,
clams, Yaquina Bay,
Bay, 1986.
1986.
One factor ANOVA:substrate
Comparison
Natural
Natural
Natural
Natural
Natural
Natural
Raked
Raked
Raked
Raked
Raked
vs
vs
vs
vs
vs
vs
Diff.
Mean Diff
raked
shell
wh shell
gr shell
gravel
wh shell/gravel
shell/gravel
gr shell/gravel
PLDS
Fisher PLDS
-1.
071
-1.071
-0.071
-0. 071
-2.571
-7.285
-6.857
_17.786*
-17.786*
7.875
7,875
7.875
7.875
7.875
7.875
7.875
1.
000
1.000
-1.
500
-1.500
wh shell
shell
shell
gr shell
gravel
gravel
shell/gravel
wh shell/gravel
gr shell/gravel
shell/gravel
gr
-5.786
_16.714*
-16.714*
7.875
7.875
7.875
7.875
7.875
vs
vs
vs
vs
gr
gr shell
shell
gravel
gravel
shell/gravel
wh shell/gravel
gr shell/gravel
shell/gravel
gr
-2.500
-7.214
-6.786
_17.714*
-17.714*
7.875
7.875
7.875
7.875
Gr shell vs gravel
shell/gravel
Gr shell vs wh shell/gravel
shell/gravel
Gr shell vs gr shell/gravel
-4.714
-4.7 14
-4.286
-15.214*
7.875
7.875
7.875
Gravel vs wh shell/gravel
Gravel vs gr shell/gravel
0.429
_10.500*
-10.500*
7.875
7.875
Wh shell/gravel vs
vs gr
gr shell/gravel
shell/gravel _10.929*
-10.929*
7.875
Wh
Wh
Nh
Wh
Wh
vs
vs
vs
vs
vs
Y1:clams/sq
Yl:clams/sq ft
shell
shell
shell
shell
-6.214
-6.2
14
*
Significant at
* significant
at 95%
95% CI
CI
Figure 15
15
Treatment
One Factor
FactorANPVA
ANPVA Xl = Treatment
One
Numbers
Bay, Sam
Sam Hayes
Numbersororlengths
LengthsManila
ManilaClams,
Clams, Tillamook
Tillamook Bay,
HayesPlot
Plot
Yl
'V1
Std.
Group
Count
Mean
Mean
Dev.
0ev.
Std.
SW.
Error
5.453
0.548
Vexar vs.
ys. No
No Vexar
13.8
13.8
Comparison
Mean
01
ff.
Diff.
Fisher
PLSO
PLSD
Numbers
1986 Numbers
Vexar
5
5
No
No Vexar
55
14.8
14.8
1.0
12.194
1.225
1987 Numbers
Numbers
1987
Vexar
33
No
No Vexar
55
15
0.2
1.
732
1.732
0.447
1.0
0.2
ys. No
Vexar vs.
No Vexar
14.8
1,903*
1.
903*
1988
Numbers
1988 Numbers
Vexar
4
4
No Vexar
4
NoVexar
4
5.5
0
I.
1.915
915
0.957
0
Vexar ys.
No Vexar
vs. No
5.5
2.343*
00
1986
1986 Lengths
Vexar
74
No
No Vexar
5
25.005
24.32
4.287
5.856
0.498
2.619
ys. No
Vexar vs.
No Vexar
0.685
4.032
1987
1987 Lengths
Vexar
45
No
No Vexar
11
30.398
30.4
0.398
ys. No
Vexar vs.
No Vexar
-0.002
5.444
1988
Len9ths
1988 Lengths
Vexar
No Vexar
No
2.672
--
--
Insufficient Data
"
Significantatat95%
95% CI
CI
* Significant
Figure 16.
Figure
16.
12.64*
200
175
175
150
150
....-0--
•
FDUNDS
PERMITS
<Jl
'4
-0
-ci
c
'"
125
<Jl
'4
:;)
:3
0a
.c
~
100
U)
CIlCil
a!:
z::
z
:::>0:
75
OR'
OW
n.n.
fl-n-
50
25
25
o0 I
.
I
i i i
i
•
I
i i i
I
'ii
I
I
I
i i i
l
196819701972197419761978198019821984198619881990
1978
1980
1982
1984
1986
1988
1990
1970
1972
1974
1976
1988
YEAR
Figure
Figure 17,
l~
Commercial
landings of bait shrimp (ghost
(ghost and
Commercial landings
mud) in
in Oregon,
Oregon, 1970-SB.
1970-88.
mud)
POSSIBILITIES FOR
FUTURE EFFORTS
EFFORTS IN
IN CLAMS
CLAMS AND
AND BAIT
BAIT SHRIMP
SHRIMP
POSSIBILITIES
FOR FUTURE
BAY CLAMS
BAY
CLHS
:t.
1.
2.
2.
3.
4.
POOR RECRUITMENT OF GAPER
GAPER CLAMS
ENCROACHMENT OF SHRIMP ON CLAM BEDS
LEASING OF TIDELANDS FOR PRIVATE MARICULTURE
LACK OF STAFF TO CONDUCT FIELD STUDIES TO MAINTAIN
MAINTAIN CURRENT
CURRENT DATA
DATA
BASE
BAIT SHRIMP
1.
:t.
2.
2.
3.
3.
4.
4.
5.
ENCROACHMENT OF SHRIMP ON CLAM BEDS
IMPACT OF FISHERY ON HABITAT
CHEMICAL CONTROL OF SHRIMP
SHRIMP (SEVIN)
(SEVIN)
COMPETITION FOR ACCESSIBLE
ACCESSIBLE PRODUCTIVE SHRIMP BEDS
LACK OF STAFF TO COLLECT BIOLOGICAL DATA
Figure 18
18.
Figure