To date, nearly one hundred species of marine finfish have been examined for larval rearing potential in Japan, of which nearly sixty species have become actual objective for intensive culture and ocean ranching (Saibai-Gyogyo in Japanese) . At present, nearly two hundred million juveniles are being produced per year (excluding salmon and trout under ocean ranching) . Red sea bream,
Pagrus majorand flounder,
Paralichthys olivaceusare the most important species, occupying almost 70% of total production. Artificially reared red sea bream and flounder juveniles are being stocked for ocean ranching (26-63% and 40-60%, respectively) . To achieve an effective contribution to ocean ranching, technology for the production of active and vigorous juveniles capable of acclimating to wild conditions is required. Diets, rearing technique, and evaluation methods under vigorous conditions are being intensively studied. Further development of intensive mariculture, establishment of fry production technology for bluefin tuna,
Thunnus thynnus, amberjack,
Serioal purpurascens, various groupers,
Epinephelusspp., northern plaices,
Verasper moseri, Limanda herzensteini, and
L. schrenkiand halibut,
Hippoglossus stenolepis, is being pursued currently. Several research subjects have been pointed out for further development of fry production technology and mariculture of finfish, i.e., 1) accumulation of biological information on larvae and juveniles, 2) development of complete microparticulated diets, 3) improvement of design and and structure of larval rearing tanks for intensive feeding of microparticulated diet, 4) protection against disease, and 5) integrative studies among various scientists and technologists of different fields. In order to develop techniques for genetic breeding and sex control, biotechnological studies are being attempted for fry production of marine finfish.
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