Golden cod persist through climate change

Abstract

This “golden cod” (left) from Gilbert Bay, off the coast of Labrador, Canada, is easily recognized by commercial harvesters because of its distinctive “golden” coloration; this fish is technically an Atlantic cod (Gadus morhua), though it is much darker than cod from the adjoining northern population (right). Atlantic cod is a population-rich species, incorporating tremendous intraspecific biodiversity, and is prized by North Atlantic fisheries. The northern cod stock, which collapsed and was placed under a fishing moratorium in 1992, has not recovered owing in part to colder-than-normal ocean temperatures in the Labrador Sea. Remarkably, while northern cod experienced high rates of natural mortality during the 1990s, the Gilbert Bay cod population grew. This golden cod spent its entire life (~17 years) in Gilbert Bay, living 6 months of the year just meters beneath sea ice in sub-zero temperatures. It therefore experienced much colder conditions, and for longer time periods, than other Atlantic cod. During summer, however, golden cod take advantage of the short growth season in the shallow waters that warm quickly within the protection of the bay.