INFLUENCE OF EPISODIC UPWELLING ON CAPELIN, MALLOTUS-VILLOSUS, AND ATLANTIC COD, GADUS-MORHUA, CATCHES IN NEWFOUNDLAND COASTAL WATERS

Wind-induced upwelling in the north-west Atlantic has been hypothesize d to influence catch rates of fish by gear fishing at fixed locations. Passive movement to shallow depths during upwelling has been proposed to increase encounter rates of fish with net leaders set at the coast . However, supporting evidence is not conclusive, possibly because fis h respond to strong events rather than all events. We investigated whe ther catch rates of capelin, Mallotus villosus, and Atlantic cod, Gadu s morhua, were related to the strength of upwelling, as measured by th e rates of water temperature change, or to stage of upwelling. Capelin trap catches were positively related to increases in water temperatur e, representing the relaxation phase. This result was due primarily to increases in catch after strong (> 4 degrees C change) rather than af ter typical (< 4 degrees C change) upwelling events. Cod trap catches were not related to upwelling strength but did increase 1-2 days after typical events. The data suggest that upwelling increases capelin mov ement, while the return of warmer surface water after an upwelling eve nt increases cod movement.