The Atlantic cod, Gadus morhua, is a demersal gadoid species found on both sides of the North Atlantic. In the Northwest Atlantic cod occur from Greenland to North Carolina. In U.S. waters, cod are assessed and managed as two stocks: Gulf of Maine, and Georges Bank and Southward. Both stocks support important commercial and recreational fisheries. Commercial fisheries are conducted year round, primarily with otter trawls and gill nets. Recreational fishing also occurs year round; peak activity occurs during the late summer in the lower Gulf of Maine and during late autumn to early spring from Massachusetts southward.

Cod may attain lengths of up to 130 cm (51 in.) and weights of 25 to 35 kg (55 to 77 lb). Maximum age is in excess of 20 years, although young fish (ages 2 to 5) generally constitute the bulk of the catch. Sexual maturity is attained between ages 2 to 4 (O’Brien et al. 1993, O’Brien 1998); spawning occurs during winter and early spring.

Cod are omnivorous, feeding on a variety of invertebrates and fish species (Lough 2004, O’Brien et al. 2005). Growth rates differ between the stocks although each is exploited by the same gear types with similar selection characteristics. Growth of cod in the Gulf of Maine has historically been slower than on Georges Bank (Pentilla and Gifford 1976, O’Brien 1998), but appears to have increased in recent years. Differences in growth rate by sex have also become less pronounced in both stocks.