The geographical distribution, population dynamics and reproductive biology of Boreomysis nobilis in Newfoundl and fjords

Abstract

The hyperbenthic mysid, Boreomysis nobilis G.O. Sars, 1879 (Malacostraca: Peracarida), is reported from nine new locations around the island of Newfoundland in eastern Canada. It is commonest within and at the mouths of deep fjords and is less common or absent outside these fjords. Its absence from two bays where the depths, temperatures and salinities are all within the range inhabited by B. nobilis in other bays indicates that other factors are probably influencing local distribution patterns. The catch rates for B. nobilis are highest in the deep water within 150 m of the bottom. However, no differences were found in the vertical distribution of the different life-history stages of B. nobilis and no evidence was found for large-scale diel vertical migrations. Boreomysis nobilis was found to breed throughout the year, since all developmental stages were present on all sampling dates. However, there was a period of increased breeding activity in the late spring and early summer. An examination of the relationship between brood size, body volume of ovigerous females, and number of stage 1 larvae indicates that B. nobilis produced a smaller number of larger larvae than expected for epipelagic and coastal mysids