Pollock undertake migrations to reach spawning grounds. The largest concentrations of spawning adults occur in Massachusetts Bay, the Stellwagen Bank, Cape Ann to the Isle of Shoals, the western Gulf of Maine and on the Scotian Shelf (Cargnelli et al. 1999). However, there is little information on the actual spawning event, and no knowledge of mating system (Cargnelli et al. 1999).

Pollock undertake north-south migrations for spawning. Spawning occurs between September and April but peaks between December and February (Cargnelli et al. 1999) . There is more variability in spawning time in northern sites than in southern sites. Spawning occurs over hard bottoms with stony or rocky surfaces, and is highly dependent on temperature. Spawning begins when water temperatures fall below 8 C, and peaks when temperatures are below 4.5 to 6 C. Spawning is reported to occur at salinities of 32 to 32.8 ppt (Collette and Klein-MacPhee 2002). Fecundity per female ranges from 200,000 to 8,260,000 eggs. Incubation time of eggs ranges from 5 to 15 days, and optimal development occurs at 8.9 C (Cargnelli et al. 1999).

Mayo et al. (1989) reported that for the period 1970 to 1984 mean age at maturity was 3.5 years for males and 3.2 years for females. O'Brien et al. (1993) reported that for the period 1986 to 1988 mean age at maturity had dropped to 2.3 years for males and 2.0 years for females.

Breeding interval: Pollock breed once yearly after reaching sexual maturity.

Breeding season: Spawning occurs between September and April, and is concentrated between December and February.

Range number of offspring: 200,000 to 8,260,000.

Range time to hatching: 5 to 15 days.

Average age at sexual or reproductive maturity (female): 2.0 years.

Average age at sexual or reproductive maturity (male): 2.3 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous

Average age at sexual or reproductive maturity (male)

Sex: male: 839 days.

Average age at sexual or reproductive maturity (female)

Sex: female: 730 days.

Parents provide no care for the young, and eggs rise in the water column and drift after fertilization. Young have a yolk sack that is absorbed after approximately five days. The rate at which yolk is absorbed is temperature dependent (Steele 1963).

Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female)