Field Guide - Walleye Pollock
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Walleye Pollock
Gadus chalcogramma
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Gadiformes
Family: Gadidae
Genus: Gadus
Species: chalcogramma
Description: Walleye pollock in Alaska are found predominantly in the Bering Sea and Aleutian Islands, with a smaller stock in the Gulf of Alaska. They can be found near the surface of the water, in shallow water when spawning or feeding, or in depths greater than 500 m. They migrate seasonally to inshore waters to either spawn or feed and move to deeper waters in the winter. They also school together in large groups.
Population status: The population is considered to be commercially well managed and is the largest US fishery by volume. It has been observed that walleye pollock have the ability to repopulate quickly in localized areas. Concerns about habitat destruction as a result of bottom trawling the ocean floor have largely been addressed through regulations enforced by state and federal agencies but should remain a priority for continued conservation.
General characteristics: Up to 91 cm, silver in color with a darker back and lighter belly, large eyes, leopard like brown spots, and 3 dorsal, 2 pelvic, and 2 anal fins.
Female defining traits: No external differences from males, but may average a few cm longer.
Male defining traits: No external differences from females, but may average a few cm shorter.
Juvenile defining traits: Newly hatched larvae are only about 4 mm in length and float at the water’s surface, and juveniles stay closer to shore.
Diet in the wild: Larger pollock eat shrimp, fish, and smaller pollock, and young pollock eat small crustaceans, krill, and worms.
Reproductive cycle: Females spawn annually in late February–May in shallow waters starting at age 2–5 and can produce over 2 million eggs over a few week’s time.
Predators in the wild: Fish, marine mammals (especially Steller sea lions and harbor seals), and seabirds.
Similar species: Pacific cod, tomcod, saffron cod, and Arctic cod.