Jaruwat Nabhitabhata *
In the last decade, cephalopods fisheries in the Gulf of Thailand had increased the importance rapidly both in quantity of landing and yield value. This means not only growing of squid population but also booming of squid luring light fishing boat. According to this, cephalopods yield pop up to 12% over potential yield. Meanwhile, trend for aiding of natural stocks and production of inexpensive protein source by coastal aquaculture is in progress in Thailand. Cephalopods, one of economic important groups, had attracted the interest in producing them as commercial culture. Research had been held, at the least, in preparation for the future.
The present result is mainly focused on three economic species of cephalopods, they are big fin squid Sepioteuthis lessoniana Lesson, spineless cuttlefish Sepiella inermis and pharaoh cuttlefish Sepia pharaonis Ehrenberg, because of their abundance in the intertidal zone. This paper is the review of serial technical paper of the studies on cephalopods culture held at Rayong Brackishwater Fisheries Station (RBFS), reporting the culturing method and also their biology and behavior.
FRAMEWORK OF CEPHALOPODS CULTURE RESEARCH
For the purpose of commercial culture of cephalopods, the studies are framed into 4 steps: they are
to studies the possibilities of rearing cephalopod in laboratory and semi-large scale
to studies and improve technique for large scale or mass culture and also in taking advantage of natural condition in floating net cage, pen as well as earthen pond culture.
to studies bio-history, biology, disease and parasite, effect of environmental factors, behavior, physiology etc.
to develope advance technique in order to increase efficiency of culturing, i.e., feed for young, artificial feed etc.
* Fishery Biologist; present address:
Rayong Brackishwater Fisheries Station,
Ban-phe, Rayong Province
First step had been held during 1980 – 1983 and so on entering the second steps until present. If the results are satisfied, fourth step should be held. The third step had been held along from the beginning and keeping on in order to supply basic information.
Cephalopods eggs were collected from natural waters as byproducts of private squid trapping, trawling and push-netting. Most of eggs from squid traps were of big fin squid. For cuttlefish, it is possible to collect and maintain parents cuttlefish, let them mate and spawn in spawning pond for convenient eggs collection.
Eggs were aerated and left to hatch in lton cement pond. Grading of new born performed by gathering all eggs in one pond and move to another after the optimum density was reached which was 200 – 400 ind./ton for squid, 400 – 800 ind./ton for spineless cuttlefish and 500 – 800 ind./m2 for pharach cuttlefish. Density of cuttlefish depends on bottom area than volume of water because of benthic behavior.
New born to 20 days old cephalopods were fed with live mysid shrimp (Mesopodopsis sp.) and small fin fish. After training, their feed were changed into fish meat (Caranx leptolepis) with live small fish, palaemonid shrimp (Palaemon spp.) and mysid shrimp (Acetes spp.) as supplement.
Size grading was held every 10 days and after that density in nursing pond was decreased for about 25% each time.
The rearing phase started after 30 days of age. For 7 ton cement pond, stocking density was decreased to 50 – 100 ind./ton for squid and 100 – 150 ind./m2 for cuttlefish.
In commercial point of view, big fin squid, S. lessoniana, is the most interesting specie because of its high growth rate which 600 gm. could be attained in about 4 months from hatching, thus at least 3 crops could be harvested annually. Eggs can be collected all year round. Food conversion ratio is 4.5:1, so closed to ratio of fin fish such as sea bass (Lates calcarifer), but survival rate at 10 – 20% has to be improved.
Spineless cuttlefish, S. inermis is the second suitability because of its good adaptation to the environment, high growth and survival rate of about 80 – 90%. Food conversion ratio is 3.2:1 by its benthic behavior with occasional pelagic behavior. Maximum and also marketable weight is only 50 – 80 gm. in about 4 months.
Pharaoh cuttlefish, S. pharaonis is seeded third, because of its slow growth although high survival rate of 80 – 90% and low food conversion ratio of 1.5:1 by benthic behavior. 100gm. of weight could be attained in about 4 months but marketable weight of 500 gm and over takes about 8 months and maximum weight of about 1000 gm. probably takes more than one year.
According to biology and behavior as well as potential suitability, two aspects of preliminary research had been held in 1984 – 1985.
Floating net cage culture of big fin squid. Stocking densities of 3 – 5 ind./m2. of production in 60 days. Culture in higher densities is in project.
Earthen pond culture of spineless cuttlefish. 45 m2. pen in 16 rai earthen pond was fenced and netted for studies. The densities of at least 6 ind./m2 was possible with production of 80 gm./m2 in 60 days.
TREND FOR FUTURE STUDIES
Food for young that will substitute live food for new born to 20 days cephalopods.
Ex-hatchery nursing, i.e., in cage, to reduce cost of seed production.
Culture in naturae water, i.e. in pen, other type of cages or any other encloser.
Studies on disease and parasite, especially bacterial and protozoan disease which, last year, gradually decreased the production.
Artificial feed for rearing. Preliminary research had been held in 1983 but result was not yet to be satisfied.
Culturing of other economic species such as Loligo spp. and Octopus spp.
Effect of environmental factors on survival and behavior, i.e., light intensity in order to increase efficiency of squid fishing.
Aquacultural physiology i.e., oxygen consumption, energy budget, to gain other views of basic information.
(Cephalopods Research of Rayong Brackishwater Fisheries Station) Nabhitabhata, Jaruwat.
1980 a. Rearing Experiment on Economic Cephalopod - I: Long-Finned Squid (Sepioteuthis lessoniana Lesson). Technical paper 1980, RBFS. 41 p.
1980 b. Rearing Experiment on Economic Cephalopod - II: Cuttlefish Sepia pharaonis Ehrenberg. Technical Paper 1980, RBFS. 62 p.
1983 External-Sex Characteristics and Sexual Activities of Long-Finned Squid, Sepioteuthis lessoniana Lesson. Technical paper 1/1983, RBFS. 28 p.
1984 a. Routine Metabolism of the Octopus, Octopus vulgaris Cuvier. Proceedings of the 22nd Conference Fisheries Section, 30 Jan. 1 Feb. 1984, Kasetsart University, Bangkok: pp 177–196.
1984 b. Trend in Commercial Culture of Cephalopods. Paper presented in Seminar on Fisheries, Production and Marketing of Cephalopods, Chulalongkorn University, Bangkok. 15 p.
1985 a. Commercial Culture of Cephalopods: Research and Trend for Coastal Aquaculture. Technical paper 5/1985, FBFS. 31 p.
1985 b. Energy Budget of the Octopus, Octopus vulgaris Cuvier. Cuvier. Paper presented in 3rd Seminar on Coastal Aquaculture, 22 – 24 May, 1983. Brackishwater Fisheries Division. 33 p.
1985 c. Mating, Egg-Carrying and other Behavior of Webfoot Octopus, Octopus membranaceus Quoy & Gaimard. Technical paper 6/1985, RBFS. 20 p.
Nabhitabhata, Jaruwat and Pitak Polkhan.
1983 a. Biological Studies on Economic Cephalopods - I: Preference on Types of Substratum of Sepiid Cuttlefish (Cephalopoda: Sepiidea). Technical paper 2/1983, RBFS. 25 p.
1983 b. Biological Studies on Economic Cephalopods - II: Survival and Growth of Cuttlefish, Sepiella inermis Fer.& Orb., in Various Salinity Conditions. Technical paper 4/1983, RBFS. 36 p.
Nabhitabhata, Jaruwat, Pitak Polkhan and Somnuk Kbilrum.
1984 Culture, Growth and Behavior of Spineless Cuttlefish, Sepiella inermis Fer. & d'Orb. Technical paper 5/1984, RBFS. 48 p.
Nabhitabhata, Jaruwat and Somnuk Kbilrum.
1981 The culture of Long-Finned Squid, Sepioteuthis Lessoniana Lesson. RBFS Annual report 1981: pp. 74–115.
1984 Biological Studies on Economic Cephalopods - III: Note on Survival of Yong Cephalopods During Continuous Change of Salinity. Technical paper 6/1984, RBFS. 9p.
Nabhitabhata, Jaruwat, Somnuk Kbilrum and Pornchai Kumpang.
1984 On Floating Net Cage Culture of Big Fin Squid, Sepioteuthis lessoniana Lesson, at Different Stocking Densities. Technical Paper 7/1984, RBFS. 42 p.
1985 On Earthen Pond Culture of Spineless Cuttlefish, Sepiella inermis Fer. & d'Orb. Technical paper 4/1985, RBFS. 28 p.
Sangpradab, Sakon, Vanchat Veschasatra and Somnuk Kbilrum
1984 a. Experiments on Feeding of Cuttlefish (Sepia pharaonia Ehrenberg) with Four Different Kind of Feed. Technical Paper 2/1984, RBFS. 15 p.
1984 b. Experiments on Feeding of Long-Finned Squid (Sepioteuthis lessoniana Lesson) with three different kind of feed. Technical Paper 1/1984, RBFS. 11 p.
Table 1 : Comparison on growth of the three cultured species of cephalopods.
|big fin squid1||spineless cuttlefish1||pharaoh cuttlefish2|
1 source : 1981–1983 data
2 source : 1980 data
Table 2 : Comparison on some biological aspects of the three species gained from culturing experiment.
|aspects||big fin squid||spineless cuttlefish||pharaoh cuttlefish|
|no. of eggs per cluster||400||300||200|
|incubation period (28°C)||20.3 days||12.6 days||14.3 days|
|age at entering adult stage||60 days||60 days||90 days|
|age at mating and spawning||112 days||87 days||113 days|
|life span||136.7 days||116.2 days||> 360 days (?)|
|approx. life cycle||3–5 months||3–4 months||> 360 days (?)|
|length-weight relationship (w=)||0.41 2.42||0.24 2.75||0.39 ML 2.20|
|food conversion ratio||4.5:1||3.2:1||1.5:1|
|approx.max. wt. weight||600 gm.||50 gm.||1000 gm.|
|natural max. wt. record||1300 gm.||80 gm.||1300 gm.|
|comparative size||larger male||larger female||larger male|
|sex ratio||m > f||m > f||m > f|