The Fish Assemblage of a Newfoundland Estuary: Diel, Monthly and Annual Variation
Twice monthly sampling over two 16 month periods at a shallow site on Newfoundlands east coast showed the fish assemblage to be dominated by four taxa that accounted for 96% of the individuals collected. Of the 16479 fish measured, 65% were adults based on the estimated size of first spawning. The fish assemblage was dominated (86%) by species with demersal eggs, several of which spawn at the same shallow sites used by juveniles as nursery sites. Coastal spawning and demersal eggs maintain offspring in coastal waster temperature being highest from mid-summer to early autumn and lowest in winter. Temperature, time of spawning, and movements of juveniles and adults, facilitated grouping species into five assemblages based on seasonal abundance; seasonal periodic species (summer and winter), regular species, regular species collected in all seasons except winter, and occasional (rare) species. At the diel scale, two consistent species groupings were observed: species that showed no significant difference between day and night and species caught primarily at night. Number of night species exceeded day species by a factor of two. No seine-caught species in shallow water exhibited significantly higher catches during the day. Observations by SCUBA divers indicated some species were more abundant during day time at slightly deeper depths. This observation in conjunction with day and night seining in shallower water, suggests these species aggregate in deeper water during day and move to shallow water at night.
30 Nov -0001
Strategic Research Theme
Oceans, Fisheries and Aquaculture