Distribution of sardine eggs and larvae related to the surface circulation in Sagami Bay

Abstract

This paper gives a description of the egg and larval distribution of the Japanese sardine,Sardinops melanosticta (T. & S.), in the surface water of Sagami Bay in connection with the water circulation. This circulation is characterized by a frontal zone, with a marked current shear between the offshore water flowing into the bay and the comparatively sluggish coastal water. The sardine larvae were most abundant in the frontal zone, while the egg distribution was mainly confined to the offshore water. The majority of the eggs were in the middle and late developmental stages, and tended to spread out towards the east following the water movement in the outer area of the front. The average size of the sardine larvae distributed in the frontal zone was appreciably larger than that in the surrounding areas. This suggests that the sardine larvae, which were transported from the offshore spawning grounds to Sagami Bay, were concentrated and retained in the frontal zone.