These fish spawn in large groups. The mating system of Theragra chalcogramma consists of females releasing their eggs and then males randomly fertilizing them (Love 1996). Females are referred to as batch spawners that release eggs every few days for one month per year.
Mating System: polygynandrous (promiscuous)
Spawning of Theragra chalcogramma occurs in water depths of 90 to 200 meters. Spawning, which occurs for an entire month, is annual and the peak spawning season fluctuates from region to region. Early spawning, in the months of February, March and April, occurs in the Bering Sea. Later spawning, in the months of April, May, and June, occurs further inward over the continental slope and shelf. Spawning fish (three- to four-year-old females and four- to five-year-old males) and pre-spawning fish (two-year-old females) swim high to mid-water in dense schools. The amount of eggs that each female holds is proportional to her body size. Females of approximately 60 centimeters produce 500,000 to 600,000 eggs while females with lengths of 40 to 45 centimeters produce about one third of that. The largest of females have been known to produce up to one million eggs (Harmann 2005). Theragra chalcogramma eggs, which are transported by currents, are planktonic (Love 1996). The eggs take anywhere from 9 to 28 days to hatch.
Breeding interval: Theragra chalcogramma spawn once yearly
Breeding season: March to August in eastern Bering Sea and January to March in Aleutian Basin
Range number of offspring: 100,000 to 1,000,000.
Range gestation period: 9 to 28 days.
Range age at sexual or reproductive maturity (female): 3 to 4 years.
Range age at sexual or reproductive maturity (male): 4 to 5 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); broadcast (group) spawning; oviparous
Besides the energy put into gamete production and spawning, Theragra chalcogramma makes no investment in its offspring.
Parental Investment: no parental involvement