Der gegenwärtige Stand der Züchtungsforschung an Meeresfischen in Japan

Abstract

1. The present status of marine fish cultivation research in Japan is reviewed. 2. In marine fish farms, the stocks have been recruited from young fish caught at sea, but recently, artificially reared fry are more and more taking the place of natural young fish, in some species. 3. The main fish species cultivated in Japanese farms are yellow-tailSeriola quinqueradiata, pufferFugu rubripes rubripes and red sea breamPagrus major; they are mostly cultivated in floating net cages set in sheltered places. 4. To increase the natural resources, the release of artificially reared young of some fishes has just started in the Inland Sea of Japan. 5. Efforts are being made to obtain ripe eggs from reared marine fishes, to hatch fertilized eggs and to raise fry: Spawning, fertilization, hatching and raising to commercial size has been achieved in several important shallow water marine fishes. 6. To keep the ambient water suitable for hatching and raising of fishes, filtration, circulation, exchange of sea water and availability ofChlamydomonas sp. andChlorella sp. (to remove metabolic wastes of the fish and to supply oxygen) have been studied. 7. Research on food sources suitable for respective stages of fishes and on the methods of producing such foods have been made. Several marine organisms are cultivated in abundance as food sources for fishes. 8. Diseases of marine fishes have been studied to keep them healthy and to enhance survival rates. 9. Some experiments on the production of hybrids between different marine fish species are now in progress; several hybrids have already been produced artificially and reared successfully.