GROWTH TRAJECTORY OF THE LARVAL JAPANESE SARDINE, SARDINOPS MELANOSTICTUS, TRANSPORTED INTO THE PACIFIC COASTAL WATERS OFF CENTRAL JAPAN

Late larvae (15-30 mm TL) of the Japanese sardine, Sardinops melanosti ctus, are commercially exploited in fishing grounds along the Pacific coast of western and central Japan. Concentrated shoals of late larvae in the shallow (15-30 m deep) coastal (4-6 miles from the coast) fish ing grounds enable fishermen to catch as much as several hundred metri c tons (t) (several billion larvae in number) per month. Growth trajec tories of sardine larvae caught in the fishing ground off Atsumi Penin sula in central Japan were individually backcalculated by using the bi ological intercept method based on the allometric relationship between otolith radius and fish length. Growth rates for larvae up to 13-21 d were high, ranging from 0.79 to 0.85 mm/d, but declined after reachin g size of immigration (13-19 mm TL) from the offshore waters to the co astal fishing grounds. The decline of growth rate in the late larval s tage seemed to be related to the concentration of late larvae in the f ishing grounds, the result of onshore intrusions of offshore Kuroshio waters. Total lengths at age 20 d were significantly smaller in 1990 ( total catch of larval sardine was 720 t) than in 1991 (total catch 300 t) in spite of a higher sea surface temperature in 1990 in the coasta l habitat. This may have resulted from a larger population of late lar vae on the fishing ground in 1990 than in 1991.