INTERANNUAL FLUCTUATIONS IN RECRUITMENT AND GROWTH OF THE SARDINE, SARDINOPS MELANOSTICTUS, IN THE SEA OF JAPAN AND ADJACENT WATERS

摘要

Recruitment and growth of the sardine Sardinops melanostictus fluctuated markedly in the Sea of Japan and adjacent waters between 1978 and 1993. Stock size was calculated using Virtual Population Analysis and average body length in each age class was determined by the number of annual rings on the scales. There is an inverse correlation between average water temperature at a depth of 50 m in the coastal area of the mainland of Japan in winter (January to March) and recruitment R defined as the number of individuals at 1 year old. There is also an inverse correlation between spawning stock size E and reproductive success ln (R/E). A multiple regression model using spawning stock size and water temperature in winter as independent variables can explain 73% of variance in reproductive success. It suggests that both density-dependent and density-independent factors perform important roles determining reproductive success. There is an inverse correlation between body length and stock size and this suggests that there is a density-dependent effect on the growth of the sardine.