Periodic fluctuations in recruitment success of Atlantic cod

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Rindorf, Anna, Cadigan, Noel, Howell, Daniel, Eero, Margit, Gislason, Henrik
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2020
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; atlantic cod; Gadus morhua; North Atlantic
• Online Access: http://dx.doi.org/10.1139/cjfas-2018-0496; http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjfas-2018-0496; http://www.nrcresearchpress.com/doi/pdf/10.1139/cjfas-2018-0496

Autocorrelation in recruitment success of fish is frequently reported, but the underlying mechanisms are generally only vaguely alluded to. We analysed recruitment success of 21 cod (Gadus morhua) stocks in the North Atlantic to investigate possible common causes of autocorrelation in recruitment. We found autocorrelation and periodic fluctuations in recruitment success and adult growth in just above half of the stocks considered and investigated six possible underlying mechanisms. With three exceptions, the variations in recruitment success were not significantly related to temperature or growth anomalies, indicating that the variation was not caused by temperature-dependent survival or growth-dependent spawning products. Further, a link between recruitment and subsequent spawning biomass could not explain the observed recruitment patterns. Slow-growing cod stocks tended to exhibit longer cycles and positive autocorrelations consistent with dilution of predation mortality by adjacent large year classes or age reading errors, whereas fast-growing cod stocks showed shorter cycles and no significant autocorrelation at lag 1. Both types exhibited significant negative autocorrelations consistent with cannibalism at one or more lags greater than lag 1.