318
17.3 Culture Methodology
Culture methodology is expressed in the Sects. 17.3.1 ‘Open Seawater System in
Tropical Countries’ and 17.3.2 ‘Open and Closed Seawater System in Temperate
Countries’ because of two reasons. First, the methodology developed in different
countries serves different main purposes: production of human food in tropical countries and production of experimental animals in temperate countries. Second, some
aspects of biological information obtained from studies in different climate zones
are contradictory, which are considered to be the results of different natural environment as well as different conditions and management in different culture systems.
17.3.1 Open Seawater System in Tropical Countries
17.3.1.1 Background
Countries in tropical zones are located near the equator, where temperatures are higher (20–30 °C), and fluctuate less, than those in temperate zones. The high temperature
enables an impressively high S� lessoniana growth rate in culture. On the other hand,
the high growth rate is accompanied by shorter life span and smaller final size. Studies of cephalopod culture in tropical countries are performed with the goal of providing food for human consumption. The information in this section comes mainly from
Thailand and other Southeast Asian countries such as Indonesia, the Philippines, and
India. Because these countries are developing countries, open seawater systems are
suitable and typically used in studies of S� lessoniana culture. Open seawater systems
require low investment, have low operational costs, and consume less energy than
closed seawater systems. In order to reduce costs, researches in these countries are
studying S� lessoniana aquaculture using in situ facilities, i.e. net cages or pens.
17.3.1.2 Broodstock Maintenance
S� lessoniana broodstock can be collected using hand jigs, squid traps, purse seine,
or lift nets operating near the shore. Squid-trapping fishermen in Thailand maintain
live squid in a ‘live chamber’ in their boats. The live chamber is a partition of the
boat that water can flow through and is similar to that used for Sepia pharaonis (see
Chap. 12). Jigs and lift nets are also proper gear for collection of broodstock. At
landing, squid can be transferred to 500-L plastic tanks for transport to hatcheries.
However, bigfin squid have a high metabolic rate and must be placed in oxygen-rich
seawater immediately after landing. A change of water or a flow-through system is
necessary after inking by the squid that is caused by handling stress. The high dissolved oxygen content of the water should also be maintained during transportation.
In hatcheries, broodstock are maintained in 2 m
3
concrete tanks at a male to female
ratio of 1:1 (Nabhitabhata et al. 2005). Pieces of fishing net with sinkers are placed
in the tanks as artificial substrates for the laying of eggs.
J. Nabhitabhata and Y. Ikeda
17.3 Culture Methodology
Culture methodology is expressed in the Sects. 17.3.1 ‘Open Seawater System in
Tropical Countries’ and 17.3.2 ‘Open and Closed Seawater System in Temperate
Countries’ because of two reasons. First, the methodology developed in different
countries serves different main purposes: production of human food in tropical countries and production of experimental animals in temperate countries. Second, some
aspects of biological information obtained from studies in different climate zones
are contradictory, which are considered to be the results of different natural environment as well as different conditions and management in different culture systems.
17.3.1 Open Seawater System in Tropical Countries
17.3.1.1 Background
Countries in tropical zones are located near the equator, where temperatures are higher (20–30 °C), and fluctuate less, than those in temperate zones. The high temperature
enables an impressively high S� lessoniana growth rate in culture. On the other hand,
the high growth rate is accompanied by shorter life span and smaller final size. Studies of cephalopod culture in tropical countries are performed with the goal of providing food for human consumption. The information in this section comes mainly from
Thailand and other Southeast Asian countries such as Indonesia, the Philippines, and
India. Because these countries are developing countries, open seawater systems are
suitable and typically used in studies of S� lessoniana culture. Open seawater systems
require low investment, have low operational costs, and consume less energy than
closed seawater systems. In order to reduce costs, researches in these countries are
studying S� lessoniana aquaculture using in situ facilities, i.e. net cages or pens.
17.3.1.2 Broodstock Maintenance
S� lessoniana broodstock can be collected using hand jigs, squid traps, purse seine,
or lift nets operating near the shore. Squid-trapping fishermen in Thailand maintain
live squid in a ‘live chamber’ in their boats. The live chamber is a partition of the
boat that water can flow through and is similar to that used for Sepia pharaonis (see
Chap. 12). Jigs and lift nets are also proper gear for collection of broodstock. At
landing, squid can be transferred to 500-L plastic tanks for transport to hatcheries.
However, bigfin squid have a high metabolic rate and must be placed in oxygen-rich
seawater immediately after landing. A change of water or a flow-through system is
necessary after inking by the squid that is caused by handling stress. The high dissolved oxygen content of the water should also be maintained during transportation.
In hatcheries, broodstock are maintained in 2 m
3
concrete tanks at a male to female
ratio of 1:1 (Nabhitabhata et al. 2005). Pieces of fishing net with sinkers are placed
in the tanks as artificial substrates for the laying of eggs.
J. Nabhitabhata and Y. Ikeda