SURVIVAL, FEEDING-ACTIVITY, AND LIVER CON STITUENTS OF RED-SEA BREAM RELEASED INTO THE SETO INLAND SEA OF JAPAN WITH SPECIAL REFERENCE TO FISH QUALITY

Domestic strains of red sea bream made by different hatcheries were re leased in the Seto Inland Sea of Japan. Group A was reared in Hakataji ma Experimental Station with an intensive system. Groups B and C were respectively reared in Momoshima and Setoda Experimental Stations with a semi-extensive system. Changes in survival, feeding behavior, and l iver constituents in the natural environment were monitored during 20 days after release. Recoveries of released fish were made by trawling till 20 days after release. Mortality in the natural environment estim ated from the recapture ratio was high in Group A (p<0.05). The fish b egan to ingest within 8 days after release and the feeding rate gradua lly increased. Perturbation caused by environmental changes after rele ase depressed the condition factor, feeding activity, and triglyceride s and protein in liver. Increase in liver acid phosphatase after relea se would be connected and would imply that hatchery procedures can be modified to improve seed quality in reference to survival and physiolo gical condition in the natural environment.