SEASONAL USE OF ESTUARIES BY WINTER FLOUNDER IN THE SOUTHERN GULF OF ST-LAWRENCE

The seasonal distribution of winter Bounder Pleuronectes americanus in the southern Gulf of St. Lawrence was examined by analyzing data from research surveys conducted from 1986 to 1994 in the southern Gulf and from beach seining, trawling, and sampling of commercial fisheries in the Miramichi Estuary. During June-August, most winter Bounder were f ound in coastal waters (<40 m deep) and within a temperature range of 3-16 degrees C. Abundance in coastal waters declined sharply between S eptember and late November-early December. Winter flounder were not ca ptured in deep offshore waters during winter; rather, large numbers mo ved into the Miramichi Estuary during October and November and remaine d until spring. The brackish water under the ice of the Miramichi Estu ary was warmer (-1 to 0 degrees C) than the full salt water under the ice of the southern Gulf (below -1.5 degrees C) and could provide a th ermal refuge for winter flounder as well as protection from ice contac t during winter storms. Adult winter Bounder left the Miramichi Estuar y by May, before the spring freshet, to move onto spawning and feeding areas.