125
7 Aquaculture to Restocking
growth on the capsule membrane and, later, infection to the embryo. In order to
reduce light, curtaining of the hatchery with a camouflage net with a light-reducing
efficiency of 80 % (Nabhitabhata et al. 2005) is the most convenient method.
Other Cephalopod Species Rearing and culture experiments associated with
other species of cephalopods occasionally produce excess numbers of seeds for
experimental performance, which can then be released for restocking (Table 7.2).
Detailed methods are provided in other chapters of this volume, such as for the
spineless cuttlefish Sepiella inermis (Chap. 13), the bobtail squid Euprymna hyllebergi (Chap. 15), the octopus Amphioctopus aegina (Chap. 18) and Amphioctopus
neglectus and Amphioctopus rex (following the methods described for A� aegina).
Post-hatching Management and Seed Releasing The hatching of cephalopod
eggs has unique characteristics. The period, from the hatching of the first egg to the
hatching of the last eggs of the same cluster of the same spawning, extends for 3–10
days. Most hatching (more than 50 %) occurs at night on the second and third day
from the first hatching. The overall hatching rate is more than 90 % (Nabhitabhata
and Nilaphat 1999) under the above-mentioned management conditions. The hatchlings pass through the basket mesh into the nursing tank. When the optimum density
in the tank is achieved, the egg baskets are transferred to another tank of previously
prepared water of similar quality.
Table 7.2 Numbers of cephalopod seeds ( × 10
4
individuals) produced and released for restocking
in Thailand during the 14 years from 1999 to 2003. (Nabhitabhata et al. 1993b, 2002, 2003, 2004,
2005; Timdee and Wongwiwatanawute 2000; Timdee et al. 2003)
Year
Sepioteuthis
lessoniana
Sepia pharaonis Others
a
Total
1990
144.68
1.26
–
145.94
1991
166.86
2.66
–
169.52
1992
304.89
15.16
–
320.05
1993
198.38
20.21
–
218.59
1994
378.64
27.00
–
405.64
1995
86.42
53.09
–
139.51
1996
187.45
14.28
–
201.73
1997
225.21
33.26
–
258.47
1998
104.65
12.76
–
117.41
1999
147.40
44.16
–
191.56
2000
166.08
12.16
2.86
181.10
2001
173.83
32.36
6.71
213.58
2002
22.01
8.36
1.28
31.65
2003
–
10.73
–
10.73
Total
2,306.50
287.45
10.85
2,605.48
Average
177.42
20.53
3.62
186.11
SE
24.34
4.12
0.97
27.42
a
Spineless cuttlefish, Sepiella inermis; bobtail squid, Euprymna hyllebergi; octopus, Amphioctopus aegina, Amphioctopus neglectus and Amphioctopus rex
7 Aquaculture to Restocking
growth on the capsule membrane and, later, infection to the embryo. In order to
reduce light, curtaining of the hatchery with a camouflage net with a light-reducing
efficiency of 80 % (Nabhitabhata et al. 2005) is the most convenient method.
Other Cephalopod Species Rearing and culture experiments associated with
other species of cephalopods occasionally produce excess numbers of seeds for
experimental performance, which can then be released for restocking (Table 7.2).
Detailed methods are provided in other chapters of this volume, such as for the
spineless cuttlefish Sepiella inermis (Chap. 13), the bobtail squid Euprymna hyllebergi (Chap. 15), the octopus Amphioctopus aegina (Chap. 18) and Amphioctopus
neglectus and Amphioctopus rex (following the methods described for A� aegina).
Post-hatching Management and Seed Releasing The hatching of cephalopod
eggs has unique characteristics. The period, from the hatching of the first egg to the
hatching of the last eggs of the same cluster of the same spawning, extends for 3–10
days. Most hatching (more than 50 %) occurs at night on the second and third day
from the first hatching. The overall hatching rate is more than 90 % (Nabhitabhata
and Nilaphat 1999) under the above-mentioned management conditions. The hatchlings pass through the basket mesh into the nursing tank. When the optimum density
in the tank is achieved, the egg baskets are transferred to another tank of previously
prepared water of similar quality.
Table 7.2 Numbers of cephalopod seeds ( × 10
4
individuals) produced and released for restocking
in Thailand during the 14 years from 1999 to 2003. (Nabhitabhata et al. 1993b, 2002, 2003, 2004,
2005; Timdee and Wongwiwatanawute 2000; Timdee et al. 2003)
Year
Sepioteuthis
lessoniana
Sepia pharaonis Others
a
Total
1990
144.68
1.26
–
145.94
1991
166.86
2.66
–
169.52
1992
304.89
15.16
–
320.05
1993
198.38
20.21
–
218.59
1994
378.64
27.00
–
405.64
1995
86.42
53.09
–
139.51
1996
187.45
14.28
–
201.73
1997
225.21
33.26
–
258.47
1998
104.65
12.76
–
117.41
1999
147.40
44.16
–
191.56
2000
166.08
12.16
2.86
181.10
2001
173.83
32.36
6.71
213.58
2002
22.01
8.36
1.28
31.65
2003
–
10.73
–
10.73
Total
2,306.50
287.45
10.85
2,605.48
Average
177.42
20.53
3.62
186.11
SE
24.34
4.12
0.97
27.42
a
Spineless cuttlefish, Sepiella inermis; bobtail squid, Euprymna hyllebergi; octopus, Amphioctopus aegina, Amphioctopus neglectus and Amphioctopus rex