growth and mortality rates of larval japanese spanish mackerel (scomberomorus niphonius) were estimated by using otolith daily increments in 1997 and 1998 in the sea of hiuchi, central seto inland sea. there was no day–night difference in the abundance and size-distribution of s. niphonius larvae in the 3–10 mm size-classes, indicating the larvae were efficiently collected by the larva-net used for sampling (1.3 m mouth diameter, 0.5 mm mesh). mean absolute growth rate (0.748 mm d−1 in 1997, 0.821 mm d−1 in 1998), weight specific growth coefficient (g: 0.402 in 1997, 0.444 in 1998) and mortality coefficient (m: 0.784 in 1997 and 0.625 in 1998) were among the highest reported for marine fish larvae. scomberomorus niphonius seems to have evolved survival strategies characterized by fast growth with strong piscivory that can reduce duration of the larval period with the high mortality. in 1997, spatial distribution of the larvae was not well corresponded to that of their prey, clupeid larvae, and the larval feeding incidence was lower than in 1998. recruitment potential assessed by examining the ratio of g:m was lower in 1997 (0.513 in 1997, 0.711 in 1998) due to the lower g and higher m values. prey fish availability may be one of the important determinants for the recruitment potential by controlling the larval mortality due to starvation and/or starvation-related predation.
Vertical and horizontal distribution of eggs and larvae of Japanese Spanish mackerel in the central waters of the Seto Inland Sea.
