325
concrete tanks. The cost of production using this method may be lower than that in
tanks because the cost of the aeration and water quality maintenance required for
both open (water flow-through) and closed systems is eliminated.
Growth
Beginning 10 days after hatching, the habit of the young S� lessoniana obviously
changes from planktonic to pelagic or nektonic. The young lower their level of
hovered swimming from near the surface level to a depth of about 50 % of the total
water depth. They begin to gather in schools of similar body size and respond to
stimuli in a synchronized manner. The ritual colour pattern on the dorsum changes
from dark brown to green and golden brown with white spots. The FL increases
from approximately 33 % of the ML at hatching to 74 % of the ML at 30 days of age
(Nabhitabhata 1978, 1983, 1996; Nabhitabhata and Kbinrum 1981).
The rate of growth is highest over the first 10-day period. In open systems, S�
lessoniana grow to 11 mm and 0.55 g by the tenth day after hatching, with a daily
growth rate of 6.7 % for ML and 17.3 % for weight (Fig. 17.3). During the first
month (0–30 days), the daily growth rate for ML is 2.8–6.7 % and the daily growth
rate for weight is 6.4–17.3 %. The relationship between ML (mm) and weight (W;
g; Fig. 17.4) in the first (nursing) phase from hatching to 30 days of age at 28 °C in
open seawater systems (Nabhitabhata 2002) is given by:
(17.1)
Growth in terms of the ML–age (T; d) relationship (Fig. 17.5) in the first (nursing)
phase at 28 °C is given by:
(17.2)
17.3.1.5 Ongrowing
Water Quality and System Requirements
The ongrowing tanks and water management systems for open systems are similar
to those for nursing of the young. Open systems operate at 24–30 °C, a higher temperature range than closed systems (20–24 °C). This results in a shorter life span
and smaller final size.
Feeding
Training S� lessoniana to feed on dead feed is a critical process which affects the
subsequent success of the ongrowing phase. At 20 days after hatching, young
3
1.508
W 1.250 10 ML
−
=
×
0.0496T
ML 0.590 e
=
17 Sepioteuthis lessoniana
concrete tanks. The cost of production using this method may be lower than that in
tanks because the cost of the aeration and water quality maintenance required for
both open (water flow-through) and closed systems is eliminated.
Growth
Beginning 10 days after hatching, the habit of the young S� lessoniana obviously
changes from planktonic to pelagic or nektonic. The young lower their level of
hovered swimming from near the surface level to a depth of about 50 % of the total
water depth. They begin to gather in schools of similar body size and respond to
stimuli in a synchronized manner. The ritual colour pattern on the dorsum changes
from dark brown to green and golden brown with white spots. The FL increases
from approximately 33 % of the ML at hatching to 74 % of the ML at 30 days of age
(Nabhitabhata 1978, 1983, 1996; Nabhitabhata and Kbinrum 1981).
The rate of growth is highest over the first 10-day period. In open systems, S�
lessoniana grow to 11 mm and 0.55 g by the tenth day after hatching, with a daily
growth rate of 6.7 % for ML and 17.3 % for weight (Fig. 17.3). During the first
month (0–30 days), the daily growth rate for ML is 2.8–6.7 % and the daily growth
rate for weight is 6.4–17.3 %. The relationship between ML (mm) and weight (W;
g; Fig. 17.4) in the first (nursing) phase from hatching to 30 days of age at 28 °C in
open seawater systems (Nabhitabhata 2002) is given by:
(17.1)
Growth in terms of the ML–age (T; d) relationship (Fig. 17.5) in the first (nursing)
phase at 28 °C is given by:
(17.2)
17.3.1.5 Ongrowing
Water Quality and System Requirements
The ongrowing tanks and water management systems for open systems are similar
to those for nursing of the young. Open systems operate at 24–30 °C, a higher temperature range than closed systems (20–24 °C). This results in a shorter life span
and smaller final size.
Feeding
Training S� lessoniana to feed on dead feed is a critical process which affects the
subsequent success of the ongrowing phase. At 20 days after hatching, young
3
1.508
W 1.250 10 ML
−
=
×
0.0496T
ML 0.590 e
=
17 Sepioteuthis lessoniana