NAUPLIAR COPEPOD CONCENTRATIONS IN THE SPAWNING GROUNDS OF JAPANESE SARDINE, SARDINOPS-MELANOSTICTUS, ALONG THE KUROSHIO CURRENT

Naupliar copepods were distributed at similar concentrations over the waters inshore and offshore of the Kuroshio Current off central Japan in early spring 1993 and 1994, overlapping with the distribution of ea rly feeding larvae of Sardinops melanostictus. Although N, P, Si and c hlorophyll a concentrations were higher in the waters inshore of the K uroshio a,:is than in the offshore waters, the mean concentrations of nauplii were not statistically different between the two waters. Food availability for larval S. melanostictus did not seem to be different between the two waters in terms of the mean food concentrations. Using the critical food concentration (>9 nauplii L-1) for 25% survival dur ing 3 days after first feeding derived from a rearing experiment, perc entages in number of stations or water samples with nauplii concentrat ions >9 nauplii L-1 were higher in the inshore waters than in the offs hore waters in both years examined. Considering that fish larvae may d epend on small-scale patchiness of food for their survival, the inshor e waters seemed to be more favourable for first-feeding larvae than th e offshore waters.