THE LONG-TERM RELATIONSHIP BETWEEN ZOOPLANKTON AND FISH

The long-term relationship between fish and zooplankton was investigated by relating In recruitment, survival or In residuals from the stock-recruitment relationship to windstress (as proxy for food) or zooplankton. The relationships were positive and negative and there was no evidence that the latter was due to offshore drift. Perhaps the true relationship is a parabolic one. Many such relationships were at the heart of events that linked recruitment to climatic change. Off California, windstress increased sharply in the late 1940s with consequences for fish stocks. Similarly, in the North Sea, the herring stock collapsed at a time when an environmental change was taking place. In the western English Channel profound changes occurred in the ecosystem which may have been related to a period of cyclonicity in the North Atlantic. (C) 1995 International Council for the Exploration of the Sea