I
COHTROLLED REARING OF DUNGENESS CRAB 47;
LARVAE
AND THE INFLUENCE OF ENVIRONMENTAL CONDITIONS ON TBEIR SURVIVAL Pib1ic Law
Law 88-309 Projeots
Projects
Publio
ANIWAL
ANNUAL REPORT
July 1,
1, 1968-June 30,
:50. 1969
Prepared
by:
Prepared by:
Approved
Approved by:
by:
Thomas P.
F. Caumer,
Gaumer, Project
Projeot BLologist
Btologist
Robert E. Loeffel,
Loeffel. Narine
Marine Research
Research Supervisor
Supervisor
Fish Commission of Oregon
Fish
U.
U. S.
S. Department of Interior Fish and Wildlife Servioe
Service Bureau of Commeroial
Commercial Fisheries Commeroial
Commercial Fisheries
Fisheries Research
Research and Development Act Subproj
ect 1-5-R-4
1-5-R-4 SUbprojeot
No. 14-11-0001-1901
14-17-0001-1907 Contract No.
October 1969
Ootober
TABLE OF COMENTS
I1iROixrOTION., .... .... ........ . ...........s...... ,. ... ,,......,. ......
INTRODUCTION...........................................................
11 AND
SS
ANDMATERIALS..................................................
MATERIALS..... .. ... ........ ØS S SIø SS
11 ~DS
NPHOD3
Efeots
Erfeots of
of diet
diet conoentxation
oonoentration on
on survival and
seowth............
oirth............
~feots of
ofcrab
or.ablarvae
larvae
oonoentration
on survival................
ifteots
concentration
on surv.va1.
.. . ..... .. . . ...
of diet
dist concentration
conoentration on
on oanniba].iem....................
cannibalism....................
Effeots of
Effects
Effeots
of light
intensity on
on the swiz,ing
s)!inm1pB behavior
behavior of
of crab
crab
Effeota of
light intensity
larvae........................................................
larvae........................................................
larvae......................................................
1 ng behavior
Effeots
on the 8!rlnwn
behavior of
of crab
crab
Effeota of
of water
water current
ourmnt on
y4n1rig
larvae0...... ....... ........ . . .. ..... s.. sos.. s.ss....
RES~S................................................................
RE3UILPS.........,.................,...............,....................
Effeota
Effeots
Effeots
Effeot8
Effeota
Effeotd
Effects
Effeots
of
of
of
of
of
of
g;rowth............
diet concentrations
oonoentrations on
on survival
survival and.
and growth.50..0.0.5.
diet
concentrations on
on survival...............
survival.00.,011.,50.
crab
orab larval conoentrations
concentration on
diet oonoentration
on oannibalisin....................
oannibalism....................
li4it 3.nteneity
cn the
the slriDl!!!ipg
swinwrdng beha'\'"ior
behavior of
of arab
crab
l:i&ht
intensi:tz cn
22 22 22 33 55 7
7
77 99 U
11
11 larvae........................................................
11
larvae....,................,......,.............,...........
Effects of
water current
Effeots
of water
on the
the
current on
~ behavior
ewiimuina
behavior of
of orab
crab ~e........................................................
).arvae..,,..,.......,,..,...,,,.,...,.,.,.,.,,...,,...........
16 1
SUMMARy................................................................
16 StJNMARY... .. .... . . ....... . . . .. .. .
..... . . .. . . . .. .... .....
17 LITEIATtRE C~.......................................................
crrEn,,.......,...............,.,.,,...,...,,........,..,.,.
LITERATURE
17
LIST OF TABLm
PM!
Table no.
no. 1
22 Page no.
no.
Size composition of Dungeness
Dungeneas crabmegalopae,
crab megalopse, by diet
concentration, 1969••••••••••••••••••••••••••••••••••••••••••••
l969..........................................
conoentration,
99
Summary'
intensity on
on aw4tmwEng
swimming
Suimnary of
of the
the effects
effects of
of light
light intensity
behavior of
crab zoese...............................
zoeae............................s..
behavior
of Durigeness
Dungeness orab
13
jei1
LIST OF FIGURES
Figure no.
no.
Figure
chamber used
to te8t
test the effects
effeots of
of different
different
1 Plexiglass chamber
uaed to
light
i ties on
on crab
arab larval
sw:hrming behavior.
behavior. Top
Top
light intens
intensities
larval swimming
photo shows
chamberinopezation.....,.........................
shows ohamber
in operation...............................
2
2
Plex1glass
chamber used
to test
effeots of
of water
Plexiglass chamber
used to
test effects
water velooity
velocity on crab
orab larval
larval swimming
s~ behavior0
behavior. Top photo shows
shows viewing
viewing
on
window.........................................................
window.... .. . . ... ... .... ..., .. ., . .. . . . ..... ..... . ... ..........
(line) and molt of
of survivors
survivors
Survival of Dungeness orab
crab zoeae (line)
3
3 SUrvival
(histograms)
••••••••••••••••••••
(1iistograme)at
atvarious
variousfood
food oonoentrations
ooncentrations...,......,....,...
4
4
44
6
8
Survival of Dungeness crab larvae at two
two different
larval
oonoentrations.................................................
concentxationa....,..,..,,...,,,...,.,....,...,.,,..,.,,.......
10
5 Effect
Effeot of
of cannibalism
cannibalism on
on survival
survival of
of Dungenese
Dungeness crab
crab zoeae
zcsae by
5
diet concentration....,
ooncentration.............................................
diet
.......a..s..s......s.s..a..aa..........
6
6
12
Average
Average total
totaJ. distance
distanoo traveled
traveled by
by fifth
fifth stage
staGe Dungenesa
Dungeness
orab
crab zoeae
zooae at l-minute
1-minute intervals by
by light intensity••••••••••••
intenaity............
Average swimming
sw:fnllling speed
speed of
of fifth
fifth stage
stage Dungeness
Dungeness crab
orab zoeao
soeae
77 Average
in each
each of
of five
five 1-minute
l-m1nute periods
periods by
by light
light intensity.
intensity••••••••••••
in
...........
14
14
15
15
CONTROLLlm REARING OF DUNGENESS CRAB LARVAE AND THE INFLUENCE OF ENVIRONMENTAL i;s a
jj;ep
II
CONDITIONS
ON THEIR
SURVIVAL
hi.
INTRODUCTION
Culture methods for Dungeness crab
crab larvae,
larvae, and
aridthe
theeffeots
effectsof
oftempera­
tempera
ture,
t various laboratory diets,
concentrations on survival
ture, salimty
salinity,
diets, and diet concentrations
survival
and
and growth were covered
covered in
in previous progress reports
reports (Reed,
(Reed, 1966,
1966, 1967
1961 and
1968). Objectives during the July I,
1, 1968,
1968, to
1969, projeot
project period
1968).
to June 30,
30. 1969,
were to
to determine
determine the
the following:
following:
were
1.
The effects
effects of
of diet
diet concentration
concentration on
on survival
survival and
and growth.
growth.
1. The
2.
effects of
of crab
crab larval concentration
oonoentration on
on survival.
survival.
2. The effects
3. The
The effects
effects of
of diet
diet concentration
concentration on
onoc.nnibalism,
or~balism.
3.
4.
4,
The
The effects
effects of
of light
light intensity
intensity on
on the
the swimming
swimming behavior
behavior of
of
crab larvae.
larvae.
crab
5.
effects of
of water current
current on
on the
the swlmm(ng
swimming behavior
behavior of
of
5. The effects
crab
crab larvae.
larvae.
A
change in project personnel in
in September
September 1968
1968 necessitated
necessitated aa
A change
slight readjustment in the program schedule in order
order that
that the new project
biologist could
could familiarize
familiarize himself
himself with
with the
the techniques
teohniques of
of holding
holding and
and
biologist
rearing orab
crab larvae.
larvae.
rearing
ME'rnODS AND MATERIALS
Dungeness crab
c~b larvae
larvae were
were generally
generallysubjeotel.
subjeote1 to
to similar
similarree.ring
reexing
Dungeness
conditions for
for each
eaoh experiment,
experiment.
conditions
wi
th an ultraviolet
ultraviolet light.
liefht.
with
All rearing
rearing water
water was filtered
filtered and
and treated
treated
Water temperatures
temperatures were
were maintained
ma.in~ned at
at 11
11 C,
C,
.:t,O.5 C,
Ct in
in aa. constant
oonstant temperature
temperature water
water bath
bath arid
and salinities
±9.5
salinities were
were adjusted
down to
to 30
30 °/
% 0 (.:t,O.5
%0
) with
distilled water.
water. Rearing water was
(.5 °/)
with
distilled
ohanged and larvae
la.rva.e were
were fed
fed three
three times
times aa week.
week.
changed
every 11
11 days.
Flaska were cleaned
oleaned about
Flasks
The larvae
larvae were
were subjected
sub~ ~cted daily
daily to
to 16
16 hours
hours (5:00
(5: 00 a.m.
a.m. to
to
9:00
9:00 p.m.)
p.m.) of
of fluorescent
fluoresoent light.
light.
2.
ovth
Effects o±
of diet
diet concentration
concentration on
on survival
survival and.
and S%owth
A diet
A
diet concentration
concentration stu&y,
study, using San Francisco
Francisco brine
brine shrimp
shrimp (Artemia
(Artemia
salina.)
determine optimum
optimum conoentrationa
concentrationsofoffood.
food
saline.) for
for food,
food, was
was conducted
conducted to
to determine
orc::"anisms to
organ.thxna
to feed
feed.ntngeness
1.ingeness crab
crab larvae.
larvae.
This
This work
work was
was an
an elaboration
elaboration of
of
efforts initiated
initiated by
by Paul
Paul Reed.
Reed in
in 1968
1968 which
which terminated
terminated prematurely
prematurely after
after
;a
38 days
days of
of rearing
rearing when
when the
the ectooommensal
ectocommensal protozoan
protozoan Vorticella
Vorticella sp.
ap. infested
infested
the zoeae.
zoeae.
Ovigerous Dungenese
crabs were provided by commercial
commercial fishermen
fishermen on
on
Dungenose crabs
January 21,
21, 1969.
1969.
Females, with
with eggs
eggs near
near hatching
hatching were
were isolated
isolated into
into
Females,
117.8 liter (31
gallon) ta.nk:s
tanks containing
individual 111.8
(31 gallon)
containing running sea water of
of
approximately 10
10 C.
C.
approximately
On January 22,
22, 180 newly hatched zoeae from
from one
one female were
oollected,
36 250
250 ml Erlenmeyer
collected, divided into groups
groups of five,
five, and placed into 36
flasks oontaining
oonta.ining 200
200 ml
ml of
of rearing
rearing water.
water.
flasks
The zoeae
zoeae were separated
separated into
into units
units of
of 30
30 and
and fed
fed aa specific
specific diet
diet
concentration
of 1,
1, 5,
5, 10,
10, 15
15 or
or 20
20 brine
brineshrimp
shrimpper
perin].
ml of
concentration of
of rdaring
rearing water.
An unfed
unfed group
group was
was reared
reared as
as aa control.
control.
An
Effects of
crab la~e
of crab
1axv.e concentration on survival
The ef±
ef1ect
by
The
eat of
ci'arab
crabl~~l
larvalconcentration
concentration on
on survival
survival was
was tested
tested by
rearing two
two groups
groups of
of five
five or&
crahzoeae
moeaevs.
vs.eleven
eleven
zoeae
per
ml of
of water.
water.
rearing
zoeae
per
200200
in].
Larvaewere
werefed.
fed at
at aa diet
diet concentration
concentrationofoffive
fivebrine
brineshrimp
shrimpper
per
ml.
Irvae
in]..
Effects of
of diet concentration
concentration on
on Gannibalism
cannibalism
The problem of
of cannibalism
canniba.lism by
by crab
crab mega.lopae
megalopae on
on YDUnber
younger crab
crab zoeae
zoeae
was reported
W9S
reported by
by Reed, 1967.
1961.
To
determine the
the effects
effects of'
of diet
To determine
diet conoentration
concentration
on this
this cannibalism,
cannibalism,crab
crabzoeae
zoeae
reared
flasks,containing
containing
ml
on
rcared
in in
250 250
in].mlflasks,
20C)200
in].
of water were fed brine
brine shrimp
shrimp at a diet
diet concentration
conoentration of
of 1, 5,
5, 10, 15
or
of
15 or
3.
3. 20 per ml of
of rearing
rearing water
water through
through the
the fifth
fifth zoeal
zoeal stage.
stage.
20
'!'he flasks
flasks were
The
were
divided into
into two
two groups
groups just
justbefore
beforethe
thezoeae
zoeaeniolted.
molted into
then divided
then
into the
the megalops
megalops
stage.
stage.
One group contained
contained 33 to
to 55 zoeae
zoeae per
per flask while the
the other
other flasks
flasks
One
held single
single zoeae.
zoeae.
held
The crab
crab larvae
larvae were
were fed
fed at
at the
the same
same diet
diet concentrations
concentrations
The
through the
the megalops
megaJ.ops stage.
stase.
through
Effects
on the
behavior of crab larvae
Effects of
of light
light intensity
inte~.on
thesw(lTmvtng
swimming behavior
larvae
To test
test the
the effects
effects of
of water current
aurrent on
on crab
orab larvae,
larvae, aa stimulus
stimulus
To
available that
that the
the larvae
larvae will respond
respond to.
to.
must be
be available
Since crab
crab larvae were
alreaay
to be
be positive phototropic, tests
tests were
were designed
designed to
to subject
subject
already known to
crab larvae to
to light.
light.
Orlgina.l.ly,
the effects
effects of
of light
intensity
Originally, plans
plans wera
wero made
made to
to observe
observe the
light intensity
on all larval
larval stages
stages of
of the
the Dungeness crab,
crab, but
but due
due to
to delays
del8¥s in
in receiving
reoeiving
on
test equipment,
equipment, the
the larvae
larvae had.
had alreaay
molted to
stage
test
already molted.
to the
the fifth
fifth zoeal
zoeal stage
before
our experiments
experiments could
could be
be atarted.
started. The
small numbers
of zoea.e
before our
The small
numbers of
zoeae
remaining after these
these tests
tests precluded extending
extending the
the experiments
experiments into
into the
the
megalops
stage.
megalops stage.
A plexiglass cind.er,
A
oy:}.inder, 154
154cmomlong
longand
and15
15Oni
om in
in diameter
diameter was
was conoon­
struoted
to test
test the
the effeots
intensity on
on crab
orab larvae
larvae behavior
behavior
atructed to
effects of light intensity
(Figure 1).
1).
(Figure
It
equipped at
at one
one end.
end with
It was
was equipped
with an
an adjustable
adjustable incandescent
incandescent
mioroscope light
8,100 foot
foot candles
candles (ft-c)
(ft-o)
microscope
light capable
capable of
of produoing
producingappro::rlmately
approTitely 8,100
of light.
of
light.
The chamber
ahamber was filled
filled with
with filtered
filtered and ultraviolet
ultraviolet treated
treated
sea
of approximately
approximately 11
11 0Cthrough
through aa half-inch
half-inohfill
fillhole
holeatatone
oneend..
end.
sea water
water of
Water in
in the
the chamber
Chamber was
ohanged after approximately 1 hour of use
Water
was changed
use to
minimize
a temperature
temperature increase.
inorease.
mir{m4ze a
The chamber
chamber was
was placed
plaoed in
in aa darkened,
darkened,
The
unheated aquaria
aquaria room of
of approximately 16
16 CC to
to eliminate
eliminate incidental
inoidental light.
light.
A
the side
side of
of the
the chamber,
chamber, reduced
reduoed the
the problem
problem
A portable fan,
fan, direoted
directed at the
of condensation
condensation collecting
oollecti.~ on
on the
the tube.
tube.
of
4.
Pigure 1.
Plexiglass chamber used to test the effects
of different light intensities on crab larval
Top photo shows chamber
swimming behavior.
in operation
5. 5'
zoeae were
were introduoed
introduced at the
the opposite end of the ohamber
chamber from
Crab zoee.e
the light source and subjected to one of three light intensities (25,
(25, 340
aM 990
and
990 ft-c).
ft-o).
The time
time the zoese
zoea.e require to reach
reach the
the bottom,
bottom" positive
positiva
or negative movement
movement (in
(in cm)
em) during
during this
this period,
period, and.
and location
location after
after 1,
1, 2,
2,
or
3, 44 and.
and 55 minutes
3,
minutes were
were reoorded.
recorded.
Zoeae were placed
plaoed in
in the chamber
ohamber one
one
Zoese
at aa time
time for
for observation.
observatio~
at
ljlffeots
of water
ourrent on_the
on the sw{mririg
swimmjp! behavior
crab larvae
larvae
Effects of
water current
behavior of crab
A chamber,
chamber, 257 cm
am long,
long. 10 cm
em wide, 14
14 cm
em high
high and
and made of
of 6.35 mm
!DID.
A
thick
tests on
on the
the effect
effeot
thick plextglass
plexiglass was
was oonstruoted
constructedto
tomake
makeprellminar,y
pre1inthy tests
of water current
ourrent on
on crab
crab larvae
larvae (Figure
(Figure 2).
2).
It vas
was equipped at the inflow
.end
end.with
withan
anadjustable
a&justable incandesoent
incandescent microscope
microscope light
light capable
capable of
of produoing
producing
approximately 3,700
3,700 ft-c.
ft-c.
was painted black vi
with
The chamber
ohamber wo.s
th a 133 x 14
am window
window left
left unpainted
unpainted on
on one
one side,
side, 92
92 cmamback
backfrom
fromthe
theinflow
inflowend..
end.
on
Ten
em seotions
the viewing chamber to
to measure
cm
sections were
were marked on the back side
aide of the
movement,
larval movement.
The chamber
chamber was
was equipped
equipped with
with aa pump
pump capable
capable of
of discharging
discharg:lJlg
The
Lowa were
were measured
measured by a cali38
at maximum
mexjmwn capacity.
capaoity. Flows
cali­
38 liters per minute at
brated flow
flow meter and regulated
regulated by either
either aa rheostat
rheostat or
or aa valve,
valve.
brated
temperature
0, ±2
;t2 C.
O.
temperature was
was maintained
maintained at
atapproximately
approvmate1y II
U C,
Water
A
A fan circulated
viewing window to
to reduce condensation.
condensation.
air across the face of the viewing
The apparatus was originally
c!tnatruoted as
as an
an open
open tr'ugh
~ but
but
origira11y constructed
problems with oontrolling
controlling water
water velooities
velocities and
and air
air ~bble8
bbblee ueee.sltated
meeoeaitated
~
the system
system to
to aa closed
closed one,
one.
changing the
Testa were originally desi8ned 'fio subj eo'1 all
5MBe8
of crab
larvae to water velooities
2.10, 4.21 and 6.32 cm
am per
per second at)ight
at~t
velocities of 2,10,
intensities of
155.0 ft-c
ft-o of
of light,
light.
intensities
of 0.75.
0,75, 66.0
66,0 and
aM 155.0
lack of test animals
Lack
and problems
and.
problems of
of design.ing
designing the
the swimming
swimming oha.mber
chamber reduced
reduced thi8
this experiment
experiment
I'
Figure 2.
of
Plexiglass chamber used to test effects
water velocity on crab larval swimming behavior. Top photo shows viewing window
1.
7. to
stage zoeae.
zoeae. These experiments
experiment8
to making pre11minar,y
preliminary observations
observations on
on fourth
fourth stage
high mortality.
were terminated prematurely due to high
RmULTS
Effects of diet concentrations
concentrations on survival and growth
All zoeae
zoeae in
in the
the unfed.
unfed control
All
control group
group were
were dead
dead by
by the
the fourteenth
fourteenth day
day
(Figure 3).
3).
The best survival
survival (46.7%)
(46.7%) occurred
occurred when zoeae
zoea.e were
were fed
fed at
at a
concentration of
of 10 brine shrimp
shrimp per
per ml.
ml.
The
The poorest
poorest survival
survival (13.3%)
(13.-,to)
occurred when
zoeae were
concentration of
of 20
20 brine
brine shrimp
shrimp per
per
occurred
when zoeae
were fed
fed at
at a
a concentration
ml.
16.7, 33.3 and
and 33.3% were experienced at diet concentra­
concentraSurvivals of 16.1,
tions
of 1,
5 and
and 15
15 per
per ml,
ml, respectively.
respeotive1y.
tions of
1, 5
This 8ubstantiated
substantiated the results
of
of previous work (Reed,
(Reed, 1968).
1968).
In contrast
contrast to
to observations
observation8 made
made by
by other investigators,
investigators, no signifi­
significant
cant inorease
increase in mortality was observed during the
the molting of
of the
the zoeae.
zoeae.
sharp increase
increase in
in mortality
was observed
observed at
at all
all diet
diet concentrations
concentrations
A sharp
A
mortality was
immediately following
following molting
molting of
of fifth
fifth zoeae
zoeae to
to mega].opae
megalopae due
immediately
due partially
partially
to
to cannibalism.
cannibalism.
Growth or
or time
time of
of molting was affected
affected at
at each
each of
of the
the diet
diet conoenconcen­
trations.
trations.
The time
time taken
taken for all
all zoeae
zoeae in
in aa test
test group
group to
to complete
complete each
each
shortest for
for zoeae
zoeae reared
reared on
on aa diet
diet concentration
concentration of
of five
five brine
brine
molt was shortest
molt
shrimp per m1
on a single day especially
especially through
through
ml and occurred predominantly on
the first three
three zoeal molts.
molts. Time
of molting
of zoeae
zoeae was
was delayed
delayed most'
most"
Time of
molting of
significantly at
at diet concentrations of 1 and 15 brine shrimp per ~.
ml.
The first observed
observed molting of
of zoeac
zoeac from
from the 1st,
1st, 2nd,
2nd, 3rd,
3rd, 4th
4th and
and
zoeal stages
the megalopae
megalopae occurred
occurred on the
5th zoea.1
stages and.
and the
the 14th, 26th,
26th, 37th,
37th, 51st,
51st,
12nd
72nd and
and.109th
109th day,
day, 't'espe';tive1y.
respetive1y.
Molting of
of zoeae into
into the
the mega.lops
stage
megalops stage
was first
first observed
observed at
at diet
diet concentrat
concentratjone
onsofof1010and
and1515brine
brineshrimp
shrimp
per
m1
was
per
in].
"
100 -­
".
Unfe\l
Unfe.
80.­
80
S.F.
sl:.rimp 10/mi
10/ml
S.F. Brine
Sine ehrimp
~
Legend
Moltir~
of zoeae
zoeae
Moltirg of
60
60·­
O§I~~
112345
2 345
40 ~,
46.7%
20 oI
I "
100
S.F. Brine shrimp
~
Ii0
o
'-'-"-~in.
Bhrimp 15/mi
15/ml
S.F. Brine Bhrimp
11m2
80 ~PI 60
'I
~ ~ 40 0
H
1
200 33.3%
33.3%
1%
0S
lC'O0
S.F. Brine sbriI!.Ji
'--\
-"--­
80 .5 60
'-,
4, 40
- .....'..,-----_.
51m2
S.F. Brine -thrimp
sbricp 20
1mJ.
20/mi
'~\ t,­
­
--
\ 33.3%
3%
20I u'.2
0
10
20
)0
*r--
I
40
50
60
10
80
90
100 10
20
4TFl:!2
ABe
in d.a\rs
Figure
3.
3.3%
.3%
.flfU15 1 Wi
30
40
50
60
70
80
90
100 Survival vf :>ungeness orab zoeo.e (line) and molt of survivors (histog.ram) at va.rious food oonoentrations
CD
•
.
72) whereas
whereas a diet of 1 per
(day 72)
per ml delayed
delayed molting
molting until
until day
day 84.
84.
On day
the first of
of two
two megalopae,
fed at a diet
diet concentration
concentration of
of 55 per
109,
109, the
megalopae, both fed
ml,
ml, moited
molted into
into post
post larval
larval crabs.
crabs.
Average size
size and
and range in
in size
size of
of the
the megalopae
meeslopae measured
measured from
from tip
tip
Average
of rostral spine to
to tip of telson when fully extended are shown
shown in Table 1
~y
y
diet concentration.
concentration.
The average
average size
size of
of the
the megalopae
megalopae fed
fed at
at diet
diet
The
concentrations of 1,
1, 5, 10, 15
15 or
or 20
20 brine
brine shrimp
shrimp per
per ml
ml were
were 7.32,
7.32, 8.25,
8.25,
8.46,
ima in
in length,
length, respectively.
respectively.
8.46, 8,45
8.45 arid
and 7.82 mIll
Megalopae
from
Meea.lopae colleoted.
oolleoted from
Bay were
were about
about 11
11 mm
mIll long.
long.
Yaquina Bay
Yaquina
Effects of
of crab
crab larva],
larval concentrations
Effects
concentrations on survival
Survival of crab larvae,
concentration of
of
larvae, reared at the same diet concentration
five brine
brine shrimp
shrimp per ml cf
cf rearing
rearing water but
but at
at two
two larval
larval densities
densities
(5
after 77
77 days
days of
of rearing,
rearing, was
was 80.0
80.0 and
and 9.6%,
9.6%,
(5 and 11 zoeae
zooae per flask)
flask) after
respectively (Pigure
(Figure 4).
4).
Crab zoeae raised at a concentration
concentration of
of 11 per
flask experienced
experienced a gradual but steady
Btea~ mortality through
thr~h the
the second
second molt
(day 26)
26) followed
followed by
by aa signi.ficant
significant increase
increase in
in mortality
mortality through the
the
next two
two molts.
molts.
next
No zoeae
zoeae in
in this
this group
group molted.
molted into
stage.
No
into t~e
the megalops
megalops stage.
Survival of zoeae reared at
characterized by irregular
irregular
at 5 per flask was characterized
periods of
of light
light mortality
mortality throughout
throughout the
the zoea].
zoeal period
period wj.th
with saveral
several
coinoidental
time of
of molting.
molting.
coincidental with time
An accelerated
aooelerated mortality,
mortality, attributed
to cannibalism,
cannibalism, oocurred
occurred for
for this
this group several days after the first
first
ocourrence
the megalopae.
occurrence of the
Table 1.
Table
1. Size
Size composition
oomposition of
of Dungeness
Dungenesscrab
orabmega],opae,
megalopae, oonoentration, 1969 by diet concentration,
Size range
range
Size
Diet concentration
oonoentration
1/mi
l/ml
5/wi
5/ml
10/mi.
10/.ml
15/mi
15Zml
20/mi
2O/ml
(mm)
{mm2
6.65-8,25
6.65-8.25
7.85-8.65
8.25-8.91
7.98-9.04
7,45-8.25
7.45-8.25
Average size
size
(mm}
(mm)
7.32
7.32
8.25
8,46
8.46
8.45
7,82
7..
82
10. 100
100 l-
'\'-""~
90
90
...,.. . . , - , - - - - .\" N
N • ;0
(5 zoeae
zoeae per
flask)
30 (5
per flask)
'\
80
\
\
70
10
11o
a,
0
,
\
,
60
60
\
F-t
'\
Pf
\
!I 50
I
flask)
\
IJ)
'i
=
\~N = 264
264 (11 zoeae
zoeae pe
per
\
\
\
40
\
\
}O
20_
s1
\
'­ -"" \
\
\
I
pie'
1:
10
20
30
}O
40
50
50
18y
Iy
60
60
70
10
80
90
90
100
1OC)
Figure
4. Survival of Dungenes8
crab larvae at two
two eitferent
~1tferent larval
Dungeneas crab
Figure 4.
concentraticns
oonoentraticna
11.
ii.
Etfects
of diet concentration
oonoentration on
on cannibalism
cannibalism
Effects of
A
decrease in
in survival
survival of
of crab
crab larvae
larvae following
following the
the appearance
appearance of
of
A decrease
the megalops
to cannibalism.
cannibalism. To determine the
megalopa is partially attributed to
significance
of cannibalism,
cannibalism, survival
survival of
of crab
crab larvae
larvae reared
reared ind.ividually
individually
8ignificance of
at densities
densities of
of 33 to
to 55 per
per flask
flask and
and fed
fed the
the same
same diet
diet concentration
ooncentration
and at
of 1,
5, 10,
15 or
or 20
20 brine
brine shrimp
shrimp per
per ml
ml was
was compared.
compared.
1, 5,
10, 15
All mortalities
observed were classified as results of cannibalism
cannibalism although natural
mortality
and cannibalism
differentiated.
mortality and.
cannibalism could
could not
not always
always be differentiated.
Survival of crab
crab megalopae,
32 days
days of
of observation,
observation, was
Survival
megalopae, after 32
higher at each
each diet
diet concentration
concentration for
for larvae
larvae held
held singularly
singularly than for
those reared
reared together
together (Figure
(Figure 5).
5).
those
Highest and
and lowest
lowest survival
survival rates
rates
Highest
recorded for
for megelopae
megelopae held
held individually
individually was
was 78%
7&% (fed.
(fed 55 brine
brine shrimp
shrimp per
per
ml) and
and 50
5Oj~ (fed 1 and.
and 20
ml)
20 brine
brine shrimp
shrimp per ml).
Survivals of 42 and
and 02
01~
(fed 10
10 and
and 20
20 brine
brine shrimp
shrimp per
per ml,
ml, respectively)
respectively) were demonstrated for
megalopae reared
reared in
in aa group.
group.
megalopae
The poorest
poorest survival
survival at
at the
the highest
highest diet
diet
The
concentration indicates that the crab larvae were receiving a sufficient
sufficient
diet but were possibly overcrowded.
overcrowded.
This was partially substantiated
substantiated by
the low survival
survival experienced
experienced with
with crab
crab larvae
larvae fed.
fed 20
20 brine
brine shrimp
shrimp per
per
ml in
in the
the diet
diet concentration
concentration study
study (Figure
(Figure 3).
3).
Effects of
of light intensity
intensity on
on the
the swimming
swimmi;ng behavior
behavior of
of crab
crab larvae
larvae
Effects
Results of
of the
the tests
tosts showed
showed that
that fifth
fifth stage
stage zoeae
zoeae exhibited
exhibited aa
in sensitivity
sensitivity to
to the
the three
three light
light intensities
intensities tested.
tested.
wide range
range in
wide
A
A
general inverse
inverse relationship
relationship occurred
occurred between
between light
light intensity,
intensity, and
and time
time
general
the distance
distance swam
swam before
before the
the zoeae
zoeae reached
reaohed the
the bottom
bottom of
of the
the light
light
and the
and
chamber.
chamber.
At aa light
light intensity
intensity of
of 25
25 ft-c,
ft-c, the
the zoeae
zoeae required
required an
an average
average
At
of 21,0
21.0 seconds and swam towards
(positive movement)
towards the light (positive
movement) aa distance
12. - -- - -r- --,-'
100 ____
80 -
'+\\\\
N
-~
1/mi
l/ml
\
'
60 Brine shrimp
S.F. Brine
shrimp 100 -k-k
4040 -
'---,
80 80­
fR . .
zoeae
4 zoea.e
\4-N
\\
~8
20
20-
\ei\
= 9 zoeae
N
\
6o
60 Q)
PI
.s 40 -
4-N
)'
60 16 zoeae
= 16
_____i-
60 40
\
20.
20
_
I
\N \
\ -<.--- N \
\N
-"""'i-I- ­
\--'')..i o
5
10
15
20
25
30
Legend.
Legend
9 zoeae
Fisak contained
Flask
oontained
3-5
3-5 zoeae
zoeae
zoeae
F].ask oontained
contained 11 zoeae
- - Flask
-.
---l--
First
oocurrenoe of
First occurrence
megalopae
megaiopae
20
20-
o0
-
I
5
10
Figure
5.
Piire 5.
15
n:a.y
]hy
20
35 1y
19 zoeae
=
8 zoeae
zoeae lay j
-
-
S.F. Brine
Brine shrimp
shrimp 20/mi
2O/ml
'-h
S.F. Brine shrimp 10/mi
80
4
'­
1:'- - ----l---L...-I...--~___:.""___"_,
$
"008&-­
40
40
-
i-N
-N
_ 16
16 zoeae
..
-,---­
0
- 16
\
80 ..
'N
20.
~~:
.0....
___________
~
0
100 S.F.
S.F. Brine
Brineshrimp
shrimp5/rn].
5/ml. 100
8
k
40_
40 -
N
7
20 -
\+"- '--------,
-;:; 90
80 ...
\
+-N
1
100 -
-\- - '<-N - 7 zoeae
60 -
\ \ 'N; : 18 zoese
zeae
0
S.F. Brine
Brineshrimp
shrimp15/rn].
15/ml
\
25
30
35 Effect of
Effeot
of cannibalism
cannibalism on survival
survival of
ofDtmgeness
Dungeness crab
orab zoeae
zoeae by
by
diet
diet oonoentration
concentration
13.
of
bottom (Table
(Table 2).
2).
reached the bottom
cm before
before they
they reached
of 7.3 om
subjected. to
to
Zoeae subjeoted
ft-c
sw-IYnmlg
of 2.8 cm
secends aM
and had.
had aa positive
positive
BW1mming movement
movement of
am
990 ft-o took 19.6 seocnd.s
reaohing the
the bottom.
bottom.
before reaching
of of
thethe
effeots
on SunEnary
effectsofoflight
light intensity
intensity on
Table
Table 2. Summar,y
swimming
swizrmiingbehavior
behaviorof
of Du.ngeness
Dungeness crab zoeae Light
intensity
:1Diinaib!;
(ft-cancties')
(ft-oa.ndles l
25
340
990
Distance
Distance travtravTime
Time to
reaoh
reach bottom
bottom eled
eled to reach
reach
(sea.)
bottom (cm)
bQjclsm!
(!ail
(lIio.l
Ra.r.lge
Ra.nge Ave!
Range
Ave. Range
Ave.
5-105
5-88
5-40
21.0
20.1
19.6
-3-100
-3-+100
+7.3
-3-+65
-2-+10
+7,2
+7.2
2,8
+2.8
Mean
distance tr&veled
traveled
Nean distanoe
time (cm)
:exMinutes
'am)
b
Minutes
1
4~
25
1t
'lbtal
14.2 4.3 10.5 8.2 6.3 43.5 6.6 8.2 9.5 9.5 7,5
7.5 41.3 5.1 8.8 4.5 10.0 6.6 35.0 The
mean
distanoe
traveled
The maximum
maximum
mean
distance
traveledby
bythe
the zoeae
zoeae
during the
during
thefirst
first
~3
2
occuxred
om) oocurred
(14.2 cm)
intensity of
ft-c
minute
(.If obeervation
of 25
25 ft-o
minute c,f
observation at
at aa light
light intensity
(Table 2). The
The minimum
distanoe
om) was
was recorded
(Table
minimummean
mean
distancetraveled
traveled (4.3 cm)
during
second minute
during the
the second
minuteofofobservation
observationatatthe
the same
samelight
light intensity.
intensity.
The
zoeal movement
forforeaoh
zoeai.
movement
eachminute
minuteofofobservation
ubservationwas
wasgenerally
generallysporadic
sporadic at
at
each light
each
light intensity.
Figure
oocurred between light
Lgure66shows·
showsthat
thatan
aninverse
inverse relationship
relationship occurred
intensity and.
and cumulative
oumula.tive average
zoea.e. The
intensity
averagedistanoe
distance traveled
traveled by the zoeae.
imil* at
light by
by the
thezoeae
zoeae was
was generally
generally similar
all
cumula.tive reaction
cumulative
reaction to
to light
at all
light intensities.
three light
intensities.
ft-c
At the end.
end of 5S minutes
m1nutes zoeae
zoeae subjeoted
25
At
subjected to 25
of light
of
light had a positive movement of 43.5
43.5 cm
am while
whilethose
thoseat
at 990
990 ft-c
ft-c
had. swum
swum 35.0 am
cm towards
towardsthe
the light.
light.
had
Swimming
speedofofthe
thezoeae
zoeaeat
at each
Swimming
speed
each light
light intensity
was generally
intensity was
sporadic
observation (Pigure
(Figure 7).
sporadic during
during each
eachof
of the
the periods
periods of observation
the first
with2525ft-o
ft-c of
of light
light
firstminute,
minute, zooae
zooae confronted
confronted with
During
exhibited
exhibited the
the
strongest attraction
at an average
attraotionand
andswam
swam at
average speed
speed of
of 2.37
2.37 mm
mmper
per second
14, 14.
5°·-------------------------------------------------; 50
foot candles
25 foot
-. -
..-
340 foct candles
40
990 foot candles
81'
'-"
0
/,//
4)
'20
/
10
/ /'
/X'
/
O~
ri
-,
_______ L_ _ _ _ _ _ _ _L __ _ _ _ _ __ L_ _ _ _ _ _ _ _L __ _ _ _ _ _
1
2
2
33
4
4
~
__
55
(minutes)
Time (minutes)
Figure
6. Average total distance traveled by
by fifth stage
stage Duagenees
Dungeness
Figure 6.
crab zoeae at l-minute
1-minute interva.ls
intervals by light intensity
~
'5.
foot candles
candles
340
candles
340 foot candles
990 foot
foot candles
990
candles
25
25
-3.50
3.00
0
12*50
2,00
'
*1
P 1.50
1
0.50
o.oo~
______ __________ ______
~
1
1
~
2
~~
3
3
Time (minutes)
(minutes) ______ ________ __
~
4
4
~
~
55 Figure 7.
Average swiDmdng
awinnning
speed
speed
ofoffifth
fifth stage
stage Dungeness
Dunseness crab
crab zoeae
7. Average
in
each of five 1-minute
l-minute periods
in each
periodaby'
bylight
light intensity
intensity
16. while those
were attracted
least (0.85
(0.85
while
those subjected
subjected to
to 990
990 ft-c
ft-c were
attracted. the
the leaat
seoond)
second).•
mm per
Swimming
Sw{''(ng behavior
behavior progressively
progressively approached
approacied uniform!ty
uniformity tbrougilout
throutiout
the
observation period
the end
end of
of 55 minutes
minutes a
a reduction
reduotion in
the observation
perioduntil
until at
at the
in
swirmning
speed8peed
was observed
at allatthree
light1iit
intensities
Bw:Lmrning
was observed
al]. three
inten8itie8and
aMthe
thediffer­
differ-
ence in
in speed
per second.
enoe
speed was
was only
only 0.20
0.20 imn
mm per
seoond.
w(iiwn(rg behavior
Effects of water
water ouxrent
aurrent on
an the
the swimmiJyr
crab larvae
Effect8
behavior ot
oi crab
Crab
and aa water
water
ft-ø and
Crabzoeae,
zoeae,subjeoted
8ubjeoted.totoa alight
light intensity
intenaity of 66 ft-o
ve100ity of
of 2.1
2.1cm
em per
per second,
seoond, generally
generally exhibited
exhibited no
no poBitive
positive reporise
response
velocity
after
release into
intothe
theawinning
mnrning chamber
chamber but
after release
butinstead
instead drifted
drifted with
with the
the
current
they settled
settled to
tothe
thebottom.
bottom.
cwrent until
until they
than 1 minute.
minute.
This
less
Thie generally
generally required les8
After
to the
the bottn,
bottom,most
mostofofthe
thezoeae
zoeaermp{ned
remained
After settling
8ettling to
in
in po8itiOn
position throl2ghout
thrO'U8'hout the 5-minute
5-m1nute observation
observation period..
period. One
One zoeae,
zoeae,after
after
settling
tothe
thebottcn
bottombelow
below the
the point
point of
of relea8e,8tarted
release, startedto
toactively
aotive1yswim
swim
settling to
against the
theourTent
currentinin8hort
shortburet8
bursts
and
and
after
after
197197
8econda
seoonds
hadhad
swum
swum65
65cm
om
(3.3 nun
mm per
speed).
per second
second average
average 8peed).
Zoeae
oflight
lightand
and4.21
4.21cm
omper
persecond.
second
Zoeae subjeoted
eubjected to
to 66
66 and
and 155
155 ft-o
ft-c of
were swept
swept out of
of the
theswimming
swimming Chamber
current were
obaniberwithin
within11minute
minuteofofrelease.
release.
SUMMARY
SUNMARY
Dungeness
San Pranoisco
Franoisoo brine ahrimp
shrimp at
Dungenes8crab
crablarvae
larvae were
were fed Sa
at
oonoentrations
10, 15
15 or
or 20
20 per
per rn].
ml.
concentrationaof
of 1,
1, 5.
5, 10,
Survival
after103
103 day8
days
Survival after
rearingwas
was highest
highest and.
and lowe8t
lowest when
diet concezltration8
conoentrations of
of 10
10
of rearing
whenfed
fedat
at diet
and
and.20
20brine
brine shrimp
shrimp per
per ml,
in]., respectively.
respectively.
Mortality
Mortality was
wasmost
mostsignificant
8flifiCaflt
the megalops
megalops 8tage.
stage.
during the
Time
when zoeae
zoeae were
ooncentration
Timeof
of molting
moltingwas
wasshortest
s1ortet when
were fed
fed at aa concezitration
of five
five brine
brineBhrimp
shrimp per ml.
ml.
Molting or
of the
through fifth
zoeal
the first
first through
fifth zoeal
stages aM
stage first
first 000urred.
on the
the 14th, 26th,
and megalops
megalops stage
occurred on
26th,
37th,
37th, 51st,
17. 109th days, respeotively.
72nd and 109th
respeotively.
Megalopa.e
IIega].opaewere
werelargest
largest (8.46
(8.46 mm)
mm) when
when
fed at
at aa diet
diet concentration
oonoentrationofof1010brine
brineshrimp
shrimpper
per
ml.
in]..
Survival
Survivaj. of
of zOGae,
zocae, reared
reared 77
77
~s
oonoentration of
of 55 and.
and 11
dars at a concentration
11
per
five brine
brine shrimp
shrimp per
per ml
ml was 80.0
per flask,
flask, and
and fed.
fed fiva
80.0 and
and 9.6%,
9.6%. respectively.
respectively.
Cannibalism
"T,r the
was
Cannibalism !.,y
themega.lopae
megalopaeononzoeae
zoeaeand
aM other
other megalopae
megalopae was
dooumented at
at all
all diet
diet concentrations.
oonoentrations.
dooumented
Fifth stage
stage orab
orab zoeae
zoeae were
were subjeoted
subjeoted to
to 24,
24, 340
340 and.
and 990
990 ft-c
ft-c of
of
light and.
and their
reoorded.
their behavior
behavior recorded.
An inverse
inverse relationship
relationship was evident
evident
between light intensity.
out time,
time, aM
anddistance
distanoecovered.
oovered by the
the
between
intensity, settling out
zoeae.
zoeae.
Swimming
speed was
was sporadic
sporadic at
at each
each light
light intensity.
inteneity.
Swining speed
Crab
using light
light as
as an
an
Crab zoeae,
zoeae, when
when subjected
subjected to
towater
watercurrent,
curent,uaig
attractor,
response. General
General behavior
behavior
attractor, generally exhibited no positive response.
was to
to settle
settle to
in that
that position
position throughout
throughout the
to the
the bottom
bottom and
and ranain
rnain in
the
5-minute
5-.inlnuteobservation
observation period.
period.
LITERATURE CITED
LITEtkTURE
Reed, P.
Reed,
P. H.,
H., 1966.
1966. Controlled
rearing cf
(t Durigeness
Dungeness crab
crab larvae
larvae and.
and the
Controlled rearing
the
influence of
of environmental
environmental conditions
oonditions cn
en their
their survival.
survival.
Commercial Fisheries Research and Development Act Progress Report,
Report,
Ncvember 16,
16, 1965,
1965, to
to Jtne
J\OJle 30,
30, 1966.
1966. Fish Commission
Commission of
of Oregon
Oregon
Ncvember
Pr~cessed
Report, lOp.
lOp.
Processed Report,
rearingof
ofDungeness
Dungeness crab
crab larvae
larvae and the
P. H.,
H., 1967.
196'i. Cortrollec].
Oontrolleu rearing
the
Reed, P.
Reed,
influence
of environmental
environmental cond.ition
oondi tione on their survival.
survival.
influence of
Commercial
CommerciaJ..Fisheries
PieheriesResearoh
Researohand
andDevelopment
Development Act
Act Progress
Progress Report,
Report,
July
Coission of
July 1,
1, 1966,
1966, to
to June
June 30,
30, 1967.
1967. Fish Commission
of Oregon
Oregon
12p.
?rocessed Report.
Report. l2p.
Processed
Reed. P.
P. H.,
H., 1968.
1968. Controlled
Controlled rearirg
rearing of
of Dungeness
Dungeness crab
crab larvae
larvae and the
the
Reed,
influence of
of environmental
environmental cond.ttiona
o.mditione on their
their survivaj.
survival.
influence
Commercial Fisheries Research and
and Development Act
Aot Progress
Progress Report,
Commercial
Report,
July
1,
1967,
to
June
30,
1968.
Fish
Coission
of
Oregon
July 1, 1967, to June 30, 1968. Fish Commission of Oregon
Report. lOp.
lOp.
Prooessed Report.
Processed