Aggressive behavior and cannibalistic behavior are com monly observed in many fishes,1,2) such as salmonids,3) carp Cyprinus carpio,4) sticklebacks,5) ...
Fisheries Science
63(1), 42-45 (1997)
Effects
of Water
Aggressive
Temperature
Behavior
Yoshitaka Ocean
Research
The
Light
Intensity
in the Juvenile
Sakakura
Institute,
and
and
University
Katsumi
on
Yellowtails
Tsukamoto
of Tokyo,
Nakano,
Tokyo
164,
Japan
(Received March 25, 1996) Effects juvenile
of
water
yellowtails
atures
at
15,
20,
temperature. served
25,
103
lx,
30•Ž,
the
light
no
of
conditions
of
aggression
occurred
intensity (16-32
frequency
light
whereas
aggression
10-2
and
quinqueradiata
and
Under at
weak
temperature Seriola
at
at
10-2
1x,
on
mm
aggressive
total
dark.
suggesting
behavior
When
fish
behavior
dark No
aggressive
TL).
,
103,
the
were
104
lx,
threshold
with the
behavior
light
to the
highest
was
of
examined
acclimated
increased
and
aggressive
were
in
water
increase
in
aggression
observed
at
intensity
the
temper water
was
10-3
lx
between
ob
whereas 10-3
and
lx.
Key words:
yellowtail, juvenile, aggressive behavior, water temperature, light intensity
Aggressive behavior and cannibalistic behavior are com juveniles of about 19 mm in total length (TL) (Series-A) monly observed in many fishes,1,2) such as salmonids ,3) and about 30 mm in TL (Series-B). Experimental fish were carp Cyprinus carpio,4) sticklebacks,5) catfish Clarias selected to minimize the size variation. Four transparent gariepinus,6) eel Anguilla anguilla,7) Atlantic cod Gadus poly-carbonate tanks (ƒÕ65 cm, 200 1), each of which con morhua,8) walleye Stizostedion vitreum,9) and yellowtail tained 1801 filtered sea water (about 50 cm in depth) and Seriola quinqueradiata.10) Cannibalistic behavior is inter one air stone for aeration, were used as rearing tanks . preted as a climax phase of aggressive behavior in the Each rearing tank poured at 0.5 l/min in water flow rate , juvenile yellowtail.11) Aggressive behavior including can of which temperature could be controlled with panel heat nibalistic behavior in a rearing pond of yellowtail has been ers and/or water coolers. Fish were acclimated for 2 days pointed out to be one of the major cause of high mortality in each rearing tank (200 fish at 20•Ž in Series-A , 150 fish at early juvenile stage 12,13)The previous study10) showed at 22•Ž in Series-B), and the water temperature was shift that aggressive behavior in yellowtail onsets just after ed gradually to 15•Ž, 20•Ž (22•Ž in Series-B) , 25•Ž, and 30•Ž f metamorphosis from larva to juvenile. or 7 to 10 days (Fig. 1). Fish were fed 3 times a day Environmental abiotic factors, such as water tempera with Artemia nauplii until satiation in Series-A , and with d ture, light intensity, salinity, and dissolved oxygen may ry pellets (C-1000, Kyowa Co., Ltd .) at about 3% of affect aggressive behaviors of fish directly or indirectly. 14,15) body weight in Series-B. On the final day of rearing , two Among such factors, water temperature and light intensity white poly-carbonate tanks each containing 301 of filtered are considered to be most important for the yellowtail sea water (ƒÕ35 cm) were set as the experimental tanks in a whose habitat is the open ocean. However, little is known water bath at each water temperature (eight tanks in total) . about the effects of these factors on aggressive behavior . Ten fish were transferred to each experimental tank 1 h af Therefore, the objective of this study is to determine the ter feeding. Frequency of chasing behavior (CHS) , which h effects of water temperature and light intensity on aggres ave been found to be available as an index to estimate the sive behavior in the juvenile yellowtail. magnitude of aggressive behavior in the yellowtail counted
Materials Experimental Two
ed ed a
reared
8) and
on
May
10),
concrete
Water Two
in
were
Artemia
as
and
described
Temperature series
of
arti
3 times
hatch
filtered
1995
(Lot-2;
ca.
500,000
larvae
hatch
dark
used
in this
study.
(90
m3)
ca.
the
Fish the
(Kyowa 22•Ž were
previous
and
were
Goto
(JASFA).
pellets at
at
reared
of
were
fed
They Co.,
light
almost
in
station
the
same
proce
study.
experiments
conducted,
using
Lot-2
individuals
Experiment
water
tanks
at 22•Ž
(room
These
e last served
(ƒÓ30 cm) (14
temperature;
cm
in
containing
depth)
were
using
for
not in
night
was a
red
to
affect time
kept
5 min
after
in
lamp the . 10) Ten
n=15) were introduced 1 h after feeding and acclimated
10 1 of placed
in a
ca . 20•Ž ), as experimental tanks were divided into
experimental
group
confirmed
,10) was repeated
were
groups with 2 tanks for each. Two groups and 104 1x using video light (Cine-Light
, about were
sea
Experiments
different
plastic
room
vation
Experiment
acclimation.
using
white
tanks.
Ltd.)
. Water condition was
1 h
Intensity
Six
larvae
of rearing in
were
900,000
dry kept
details
which
ca.
Association
was The
yellowtails, (Lot-1;
pond
Sea-Farming
natural.
10)
1994
rearing
temperature
dures
juvenile
in year
May
with
1 to
. Light
of
on
Japan
Methods
Fish
batches
ficially
and
after
total
, which behavior fish
were
kept
at 103
, Blom
Co.,
Ltd). Th
darkness
, and was ob had been previously of yellowtail as obser
(Lot-1;
15.3•}2
to each experimental frequency of CHS was for
3
1 h .
Experiments
.9mm
in TL tank counted were
Aggression repeated
3 times
Light
using
Threshold
In
order
sity
for
different
determine
aggressive
the
critical
behavior,
(ƒÕ54 cm), for each.
was placed in two These tanks were
in
depth)
room as
al.16)
was
a control in
dark),
with
tensity
with
kept
change
(40
W)
(transmit measured Ltd;
32.9•}6.2
tank lx.
about 1 After
min
in
video viewer, the
the
by
vinyl
mm
in
1x)
TL,
experiment.
was
given 10-3,
10-4,
in which
level
of light
vinyl
covered 740
nm).
light 300
Experiments
10-2,
CHS
Hitachi
photonix
was
10-1,
tank.
(Eye-Ball,
introduced
acclimated
intensity
lx, then
Co.,
was
with
10-3,
10-4,
observed
Ltd.)
during
repeated
each
1 h at 300
changed
Ltd.
at (Lot
to
for
Co.,
were
from fish
and the
Temperature
Frequency
Alek
Ten
Results Water
intensity
calculated
Statistics Statistical analysis on frequency of CHS was done using the Bartlett's test for comparison of the variances. The one-way analysis of variance (ANOVA) was applied when there was no significant difference between the variances of the different groups (p>0.05 by the Bartlett's test). In cases where significant differences were found among the means by ANOVA (p0.05). In and increased
temperature
was 15•Ž.
at 25•Ž showed intermediate 30•Ž, although there were (Duncan's
Series-B, according
New
aggression to the
ture
course
p
