Dispersion of Eggs, Larvae and Pelagic Juveniles of White Hake (Urophycis tenuis) in Relation to Ocean Currents of the Grand Bank: A Modelling Approach

Abstract

White hake (Urophycis tenuis) is a temperate demersal fish species distributed in the northwest Atlantic. On the Grand Bank, it is concentrated mainly to the southwest where water temperatures are warmest. Survey data indicate that mature adult females aggregate on the southwest (SW) Grand Bank slope in spring and first-year juveniles settle on the southern, shallow Grand Bank in autumn. Dispersion patterns and survival potential of eggs, larvae and juveniles were investigated with respect to the effects of location (horizontal and vertical) and timing (monthly) of spawning under monthly-mean circulation fields, M2 tidal currents and associated turbulent mixing computed from a three-dimensional regional ocean circulation model. The results indicate that releases below the surface Ekman layer and in late spring have the highest chances for juveniles to settle in the southern Grand Bank nursery area in autumn. On an interannual scale, the strong recruitment of the 1999 yearclass has been used as an example to examine the potential linkage between recruitment and the strength of the Labrador Current. A weak along-slope current and strong on-bank flow contributed to the strong recruitment of the 1999 year-class.