RELATIONSHIP BETWEEN BATCH FECUNDITY AND EGG SIZE IN JAPANESE SARDINESARDINOPS MELANOSTICTUS IN TOSA BAY AND OFF KII CHANNEL, SOUTHWESTERNJAPAN FROM 1990 TO 1993

The relationship between batch fecundity and egg size in Japanese sard ine Sardinops melanostictus in Tosa Bay and off the Kii Channel, south western Japan from 1990 to 1993, was examined using females whose yolk volume of oocytes became constant after hydration at the final matura tional stage. Positive correlations were recognized between these two among females whose batch fecundities were less than 30,000 eggs, whil e negative correlations were recognized among females those of which w ere more than 30,000 eggs, even if they were of the same body length o r age. From 1990 to 1992, the former females distributed in the coasta l area of Tosa Bay with relatively low surface temperature, while the latter females distributed in the offshore area of Tosa Bay or the fro ntal region of the Kuroshio Current off the Kii Channel with relativel y high surface temperature. In 1993, these offshore spawners in the Ku roshio region became almost extinct, simultaneously many females that spawned more than 30,000 eggs per single spawning were observed in Tos a Bay. These results suggest that the spatial changes of batch fecundi ty of sardines from 1990 to 1992, which influenced the egg size, resul ted in the population-specific fecundity.