Spatial distribution of Japanese sardine, gizzard shad and Japanese anchovy larvae in the Sea of Hiuchi, central Seto Inland Sea, in the 1990s

摘要

In contrast to the collapse of Japanese sardine Sardinops melanostictus population in the western North Pacific in the early 1990s, the annual catch of the Japanese sardine peaked in the Sea of Hiuchi, central Seto Inland Sea, Japan, in 1997. Larvae of the three clupeiform fishes, Japanese sardine, gizzard shad Konosirus punctatus and Japanese anchovy Engraulis japonicus, were simultaneously distributed in the Sea of Hiuchi during the late 1990s. In order to compare the early life histories of the three species, seasonal occurrence and spatial distribution of the larvae were investigated before (1982), during (1995-1998) and after (2008) the abrupt increase in Japanese sardine population in the Sea of Hiuchi. Corresponding with the trends in the annual fishery catch of each species in the Sea of Hiuchi, Japanese anchovy larvae were most dominant among the clupeiform species in 1982, Japanese sardine and gizzard shad larvae in 1995 and gizzard shad and Japanese anchovy larvae in 2008. Overlap in horizontal distribution was most evident between Japanese sardine and gizzard shad larvae. However, the pattern of vertical distribution differed between larvae of the two species; Japanese sardine larvae were more abundant in mid and bottom depths while gizzard shad in surface layer.