NEARSHORE ICHTHYOPLANKTON OF A NORTH TEMPERATE ESTUARY

Composition of ichthyoplankton in the nearshore zone (0-6 km from shore) of the St. Lawrence estuary showed important differences from that farther offshore. In particular, larvae of herring (Clupea harengus harengus), winter flounder (Pseudopleuronectes americanus) and smooth flounder (Liopsetta putnami) made up a greater proportion of the ichthyoplankton than in published surveys farther offshore. Peak catches of larval herring were 1-2 orders of magnitude higher than in offshore waters. Winter flounder and smooth flounder larvae were significantly more abundant .ltoreq. 500 m from shore than 1-6 km offshore; significant abundance gradients were not found for other species. Nearshore areas have received considerably less effort than offshore areas in earlier studies, and more intensive studies in the nearshore zone, at least for those species mentioned, would be of importance for elucidating early life history processes and for estimating spawning biomass based on ichthyoplankton surveys.