Density of juvenile cod in coastal Newfoundland habitats : multiscale analyses of spatial and temporal variation

This thesis examines the relative importance of small-scale spatial and temporal variation in density of coastal populations of juvenile cod, Gadus morhua and how identification of this variation may contribute to a better understanding of the early life history and to the design of better sampling programs. This thesis also considers sampling variation due to fishing equipment and species identification. Populations of marine fish exhibit strong variation in yearclass strength. Hence annual variation in density was expected to exceed variation at monthly and hourly scales. Contrary to expectation, temporal variation was highest at a monthly scale for two intensively sampled sites, and was attributed to cod settling in coastal habitats in pulses during May-June, August-September, and after mid October. Settlement in May-June and after mid October was due solely to G. morhua. Settlement in August-September was by G. morhua and G. ogac, a sibling species that is presently difficult to identify at