Stock assessment and release strategy of red sea bream Pagrus major in Kagoshima Bay, Japan

Population sizes of red sea bream (RSB) Pagrus major in Kagoshima Bay were estimated both for wild and released fish by cohort analysis from 1990 to 2002 to consider its fishery management and release strategies. The analysis showed that the population size of released fish had decreased while that of wild fish remained stable. The commercial catch of wild fish tended to decrease as that of released fish increased over 50 tons. The results suggested that the RSB enhancement program with the scale of 700-800 thousand seeds released and 50 tons recaptured was appropriate. Predictions of red sea bream catch in 2017 by a simple population dynamics model under various scenarios of fishing regulation and seed release showed that the catch increases under the enhancement program with improved stocking efficiency.