Walleye pollock (Gadus chalcogrammus)

Walleye pollock
Walleye pollock
Category: Fish
Related species groups: Codfish
Vulnerability to climate change (More details)

Moderate

Populations of this species

Occasionally caught off the Washington coast by commercial harvesters using otter-trawls.

Description and Range

Physical description

Walleye pollock have an elongate olive-green to brown body, often with faint blotching or mottling above, silvery sides, and a whitish belly. They have three dorsal fins and 2 anal fins. The lower jaw projects slightly beyond the upper jaw and a chin barbell is tiny, if present at all. The first anal fin of this species is usually pale and the other fins are dusky. Young walleye pollock have 2-3 narrow yellowish stripes along their sides.

In Puget Sound, walleye pollock can grow up to 3 feet (91.4 centimeters) in length and live up to 10 years. In Alaska, walleye pollock can live much longer -- up to 22 years -- while growing up to 3.4 feet (105 centimeters) long and weighing up to 13.3 pounds (6.05 kilograms).

Geographic range

Walleye pollock range from the northeastern Pacific Ocean from the Seas of Japan and Okhotsk, east in the Bering Sea and Gulf of Alaska, and south in the northwestern Pacific Ocean along the Canadian and U.S. west coast to Carmel, California. The highest densities of most populations are in the North Pacific Ocean, including the northern Gulf of Alaska, Bering Sea, and the Sea of Okhotsk, suggesting that walleye pollock populations in the Puget Sound are relatively isolated and genetically distant.

They are found off shore and adults and juveniles move up and down through the water column depending on the time of day. Adults have been documented as deep as 1,200 feet (366 meters), but the vast majority occurs between 328 to 984 feet (100 to 300 meters).

Climate vulnerability

Sensitivity to climate change

Moderate

Walleye pollock are likely to be sensitive to increases in sea surface temperature, particularly since Puget Sound is the southern limit of their range. Cooler waters support higher levels of pollock recruitment and larval survival because cooler waters promote increased production of primary prey species for pollock (e.g., copepods, euphausiids, other zooplankton). For pollock in the Bering Sea, it was found that though warmer spring conditions during spawning season enhanced early survival of larvae, continued higher temperatures led to poor feeding conditions and reduced recruitment the following year. Thus, predicted warming could result in decreases in prey abundance and declines in recruitment, larval survival, and productivity and potential northward range shifts of Walleye pollock.

Confidence: High

Exposure to climate change

Moderate

  • Increased ocean temperatures
Confidence: Moderate

Regulations

Rules and seasons

Recreational harvest within Puget Sound is now closed, with the exception of restricted fishing in the San Juan Islands and Strait of Juan de Fuca.