CONCLUSIONS, REFERENCES

CONCLUSIONS

An urgent need in Japanese yellowtail aquaculture is the production of better quality juveniles, with better growth rates and less vulnerability to disease. This should be accomplished through selective breeding, which requires collection of different strains in order to select the required broodstock.

A further additional development may be culturing marine species, such as yellowtail, on land. If the culture of yellowtail and related species becomes possible on land without polluting coastal areas, it will be a welcome approach for producing high quality fish (Kikuchi, 1998). Previously land-based culture was not considered because of the high initial cost for facilities; however it may now be a feasible approach. The fish can be raised in controlled quality water, resulting is fewer diseases and reduced exposure to pollutants. This approach is attractive to consumers, who increasingly prefer cultured fish which they know have not received medication. A moist pellet for yellowtail was developed ten years ago, as well as formulated feed. Furthermore, artificial seawater systems that perform better than natural seawater for larval production have been developed and techniques for closed systems and automatic feeding systems are improving regularly (Nakada, 1997b). However, there remains the problem of finding suitable heat sources to control water temperature.

At present, there are no proper countermeasures for the declining productivity of the fish in growout areas, or for controlling disease in intensively cultured fish. For economical and sustainable fish culture it is necessary to maintain an optimum stocking density based on carrying capacity. Hirata and his colleagues (Hirata, Kadowaki and Ishida, 1994) proposed developing a distribution graph of dissolved oxygen concentrations in culture areas to aid proper water management. This can now be supported by the recent availability of real time information on the dissolved oxygen and water temperature of particular areas from the fisheries experimental station and fishery cooperatives.
In order to alleviate the environmental problems associated with marine fish farming, various measures are needed such as dredging accumulated sediment from the sea bottom, using chemicals to stimulate decomposition of organic materials, prohibiting the use of minced raw fish, and prohibiting the culture of large yellowtail in favour of culturing smaller, less polluting fish. Additional measures include increasing the propagation of lugworms, which consume organic material in the mud, and cultivating algae, which absorb dissolved nutrients excreted by fish. The comprehensive utilization of natural productivity may be the correct direction of aquaculture in the future (Tsutsumi and Montani, 1993).
It is time to consider a comprehensive culture approach that utilizes the natural purification ability of the environment. Such an approach may involve polyculture not only of several species of fishes, but also of crustaceans and algae (Hamauzu and Yamanaka, 1997).

REFERENCES

Abe, T. 1986. Fish Data - I. Fish names and illustrations. 75th Anniversary of the establishment of Nihon Suisan Co., Ltd., Tokyo.
Abe, T. 1987. Illustrated fishes of the world. Hokuryu-kan, Tokyo (in Japanese). Abe, T. & Homma, A. 1997. Modern fish dictionary, NTS Inc. Tokyo.
Anraku, M. & Azeta, M. 1967. Seikai Regional Fisheries Research Laboratory Report 214(35): 41–50.
Arakawa, T., Takaya, M., Kitazima, T., Yoshida, N., Yamashita, K., Yamamoto, H., Izquiero, M.S. & Watanabe, T. 1987. Propagation experiments of horse mackerel. Bulletin of Nagasaki Prefectural Institute of Fisheries, 13: 31–37.
Fukuhara, O., Nakagawa, T. & Fukunaga, T. 1986. Larval and juvenile development of yellowtail reared in the laboratory. Bull. Japan. Soc. Sci. Fish., 52(12): 2091–2098. Hamauzu, K. & Yamanaka, M. 1997. Effect of additional seaweeds feed for yellowtail. Suisan-Zoshoku, 45(3): 357–363.
Hirata, H., Kadowaki, S. & Ishida, S. 1994. Evaluation of water quality by observation of dissolved oxygen content in mariculture farms. Bull. Natl. Res. Inst. Aquac., Suppl. 1, 61–65.
Ikehara, K. 1984. Nihonkaiku Regional Fisheries Research Laboratory Report, pp. 221–232. Inagaki, M. 1990. History on the supply and demand of yellowtail juvenile (Mojako) (Special Reports on Buri). Suisan-Zoshoku, 38(3): 300–314.
Kawabe, K., Kato, K., Kimura, J., Okamura, Y., Ando, K., Saito, M. & Yoshida, K. 1996. Rearing of broodstock fish and egg taking from amberjack Seriola dummerili in the Chichi-jima, Ogasawara Island, Southern Japan. Suisan-Zoshoku, 44(2): 151–157.
Kawanabe, K., Kato, K., Kimura, J., Okamura, Y., Takenouchi, T. & Yoshida, K. 1997. Rearing of broodstock fish and egg taking from the Carangid fish Seriola revoliana in the Chichi-jima, Ogasawara Island, Southern Japan. Suosan-Zoshoku, 45(2): 201–206.
Kikuchi, K. 1998. New land aquaculture system. Brochure of Technical Bulletin of Hitachi Metals, Tokyo, 1–4, Jan.
Matsumoto, S. 1997. Law and administrative guidance for aqua-feed. Yoshoku, 34(5): 49–51.
Miyazaki, T. 1986. Prevention and treatment of diseases in yellowtail. Yoshoku, 23(9): 101–103.
Mushiake, K., Arai, S., Matsmoto, A., Shimma, H. & Hasegawa, I. 1993. Artificial insemination from 2-year old cultured yellowtail fed with moist pellets. Bull. Japan. Soc. Sci. Fish., 59(10): 1721–1726.
Nagasaki Prefecture Fisheries Experimental Station. 1998. Report from Experimental Station. Monthly Kansui, 403, 44–44.
Nakada, M. 1992. Current study for aquaculture feeds. Yoshoku, 29(8): 38–60. Nakada, M. 1997a. Economical usage of artificial aqua-feeds. Yoshoku, 34(5): 60–64. Nakada, M. 1997b. Auto feeding system and formulated fish feed-study of auto feeding. Marine Forum 21, pp.168–172.
Nakayama, H. 1997. Present status and problems of artificial aqua-feeds. Yoshoku, 34(5): 60–64.
Sakakura, Y. & Tsukamoto, K. 1996. Onset and development of cannibalistic behaviour in early life stage of yellowtail. J. Fish Biol., 48, 16–29.
Satoho, R. & Homma, A. 1990. Handling of live fish. Fuji Technosystem, Inc., Tokyo. Shimeno, S. 1997. Current study for aquaculture feeds. Yoshoku, 34(5): 52–55. Shimeno, S., Masaya, M. & Ukawa, M. 1997. Effect of manufactured cooking level on
nutritional value for high fishmeal contained yellowtail feed, Bull. Japan. Soc. Sci. Fish., 63(6): 971–976.
Shimeno, S., Takii, M. & Ono, T. 1993. Difference of digestion and blood plasma change for juvenile yellowtail by raw fish feeds and artificial fish feeds. Bull. Japan. Soc. Sci. Fish., 59(3): 507–513.
Suehiro, Y. & Abe, T. 1994. Illustrated book of fishes and shellfish. Shogakukan, Tokyo. Tachihara, K., Ebisu, R. & Tukasima, Y. 1993. Spawning, eggs, larvae and juveniles of the purplish amberjack Seriola dummerili. Bull. Japan. Soc. Sci. Fish 59(9): 1479–1488. Takeuchi, T., Shiina, Y., Watanabe, T., Sekiya, S. & Imaizumi, K. 1992. Suitable protein and lipid levels in diet for fingerlings of yellowtail. Nippon Suisan Gakkaishi (Bull. Japan. Sco. Sci. Fish.), 58: 1333–1339.
Tsutsumi, H. & Montani, S. 1993. Utilization of biological activities of capitellid polychaete for treatment of “Hedoro” (organically enriched sediment) deposited on the marine bottom just below fish net pen culture. Nippon Suisan Gakkaishi (Bull. Japan. Sco. Sci. Fish.), 59: 1343–1347 (in Japanese).
Verakunpiriya, V., Mushiake, K., Kawano, K. & Watanabe, T. 1997a. Supplemental effect of astaxanthin in broodstock diets on the quality of yellowtail eggs. Fish. Sci., 63(5): 816–823.
Verakunpiriya, V., Watanabe, K., Mushiake, K., Kawano, K., Kobayashi, T., Hasegawa, I., Kiron, V., Satoho, S. & Watanabe, T. 1997b. Effect of krill meal supplementation in soft-dry pellets on spawning and quality of egg of yellowtail. Fish. Sci., 63(3): 433–439.
Watanabe, T. 1996. Developments in the present conditions of Japan aquaculture feeds, Suisan-Zoshoku, 44(2): 227–229.