Atmosphere–Ocean Coupling and Atlantic Cod Migrations: Effect of Wind-Forced Variations in Sea Temperatures and Currents or Nearshore Distributions and Catch Rates of Gadus morhua

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Rose, G. A., Leggett, W. C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1988
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; atlantic cod; Gadus morhua
• Online Access: http://dx.doi.org/10.1139/f88-145; http://www.nrcresearchpress.com/doi/pdf/10.1139/f88-145

Coastal upwellings and downwellings forced by alongshore winds on the north shore of the Gulf of St. Lawrence were associated with variability in onshore movements and inshore daily catches of Atlantic cod (Gadus morhua). Mean cod densities in the zone offshore from the trap sites, determined by hydroacoustic integration scaled by an in situ dual beam determined mean backscatter, ranged from 2.6 to 82.7 fish/10 5 m 3 . Cod were located where sea temperatures ranged from −0.5 to 8.5 °C. Catches were nil where temperatures were outside this range. Cod were located at depths which correlated with the strength of alongshore currents (r = −0.55). A path analysis model with predictors alongshore wind stress and current, sea temperature, and cod density accounted for 76% of the variance in catch. Cod abundance in the offshore zone accounted for the most variance independent of other factors (27%). Sea temperature and currents accounted for 15 and 13%, respectively. Peaks in catch (to 1500 kg/d) coincided with maximum rates of decline in sea temperatures and with NE upwelling currents. Low catches coincided with maximum rates of increase in temperatures and with SW currents. In a regression model, four lags of alongshore wind accounted for 83% of the variance in catch.