Morphometric and Electrophoretic Approaches to Discrimination of Capelin (Mallotus villosus) Populations in the Estuary and Gulf of St. Lawrence

Abstract

The degree of differentiation between capelin (Mallotus villosus) populations in the Estuary and Gulf of St. Lawrence was evaluated using conventional and truss morphometric analyses together with electrophoretic analyses of protein-coding loci. Samples of spawning fish were collected in the same year at eight sites across NAFO divisions 4R, 4S, and 4T. While the results of conventional morphometric analyses were not conclusive, truss and electrophoretic analyses differentiated the sampled sites along an east–west axis. Two samples (one from the Southern Gulf and the other from the Northeastern Gulf) did not follow this trend. Processes are suggested to explain this pattern. Variations in allelic frequencies among age-classes of fish have been observed in some samples and may be attributed to selective environmental pressures. This could explain the apparent population differentiation observed, although the distribution of the alleles revealed a high gene flow.