Title Estimate of optimum stocking density of hatchery-raised Japanese flounder juveniles in Ohno Bay, Northeastern Japan
Authers Yoh YAMASHITA, Yutaka KURITA, Hideaki YAMADA and Kazutaka TAKAHASHI
Keywords flounder, stock enhancement, stocking density, carrying capacity, ecophysiology model
Citation Bull. Fish. Res. Agen. supplement No. 5, 169-173, 2006
Abstract
In order to estimate the surplus productivity of nursery grounds available for stocked fish, we developed a sub-population growth model for juvenile Japanese flounder Paralichthys olivaceus. Using this model, we predicted the optimum stocking density above which release of hatchery-raised juvenile flounder would restrict the growth of conspecific wild juveniles as food availability will begin to limit subpopulation production. The optimum stocking density for 8.5 cm TL flounder was estimated to be zero in Ohno Bay 1990 and 17,000 individuals per 250,000 m2 in 1991. This indicates there was no surplus productivity for stocking of hatchery-raised flounder juveniles in the case of Ohno Bay 1990. The most important factors to affect optimum stocking density of flounder were the abundance of mysids and wild flounder juveniles at the time of release. The difference in the optimum stocking density between 1990 and 1991 was thought to be caused by those in wild flounder density (19.8 inds/1,000 m2 in 1990 and 6.8 inds/1,000 m2 in 1991)and in mysids abundance (177.5 mg/m2 in 1990 and 393.5 mg/m2 in 1991).
URI http://www.fra.affrc.go.jp/bulletin/bull/bull-b5/29.pdf