Seasonal distribution, abundance, and life-history traits of Greenland cod, Gadus ogac, at Wemindji, eastern James Bay

Abstract

Greenland cod populations near Wemindji, eastern James Bay, were studied in 1987 and 1988 to describe the species' general ecology and life-history characteristics. During the summer, they principally occupied shallow (2–5 m) coastal waters. This habitat was characterized by a belt of eelgrass (Zostera marina) at depths of 1–3 m, salinities between 20 and 23‰, and temperatures of 3–20 °C. Daily trap catches were highly variable, and more fish were caught at night than during the day. In winter, more cod were found inshore, in the estuary, than in coastal waters. This movement corresponds to the completion of sexual maturity; spawning occurs in April to June. Growth rate was linear for males and females. The age at maturity was 3 years and no trade-off was observed between growth and reproduction. Greenland cod spawned every year, and the maximum age was 9 years. Life-history variables for Greenland cod differ from those of most arctic benthic fishes; this species shows rapid growth, high fecundity, low age at maturity, and high mortality. These characteristics may represent important adaptations allowing cod to sustain life in James Bay coastal waters, where environmental conditions are different from those in arctic waters.