Dispersion, Homing, and Group Cohesion in Atlantic Cod

Knowledge of the effect of environmental factors on the migratory behavior and dispersion patterns of fish is important. This knowledge is essential for the development of plans for rebuilding and conservation of depleted stocks such Atlantic cod. In this context, we examined how the distribution of Atlantic cod (Gadus morhua) is influenced by abiotic and biotic factors based on tagging-recapture. We analysed the homing behaviour and group cohesion in Atlantic cod from the northern Gulf of St Lawrence  based on tagging-recapture data from two periods, the 1980s and a recent period from 1996 to 2008. The dispersion index was significantly related to temperature, habitat suitability and biomass but not to salinity or depth. These results indicate that interannual fluctuations of temperature and stock abundance both influence the dispersion pattern of cod. Results show that the Cod population exhibits a homing behaviour, with temporal stability over several years. In addition to site fidelity, cod showed group cohesion. Such informations are critical for improved understanding of the behaviours and dispersal patterns of the cod stock in the northern Gulf of St. Lawrence in relation to their environment for assessing the potential consequences of management actions.