DISTRIBUTION PATTERNS OF BALTIC HERRING LARVAE, CLUPEA-HARENGUS L, IN THE COASTAL WATERS OFF HELSINKI, FINLAND

Changes in the spatial distribution of Baltic herring larvae through time were investigated in the waters off Helsinki, the northern Baltic Sea. The average larval densities were comparable to the relatively low levels (mean around 2 larvae m-2) found in other studies in the Gulf of Finland. In shallow bays virtually no herring larvae were found in early June. In late June and early July the densities of larvae longer than 10 mm increased to 1-4 larvae m-2 in shallow areas (depth <2 m), i.e. to levels higher than those recorded in deeper waters. In combination with data on the size distributions of the larvae, these observations suggest that a significant proportion of the herring larvae are found in shallow water after the yolk sac stage. We conclude that shallow coastal waters are potentially important nursery areas for herring larvae and that this feature of herring larval biology should be taken into account in planning sampling programs for larval herring. © 1990 Oxford University Press.