Alaska Pollock (Theragra chalcogramma)

• Alaska pollock population levels are estimated to be below target levels in 2008, but harvest limits are adjusted accordingly and strictly adhered to. No overfishing is occurring.
• The Alaska pollock fishery is the largest U.S. fishery, by volume. Annual catches average 2.5 billion pounds.
• Alaska pollock is high in protein and low in carbohydrates and fat. For more information, see Nutrition Facts. (USDA)
• Almost all the pollock sold in the U.S. is caught by U.S. fishermen; imported pollock accounts for less than 2% of the pollock consumed domestically.

Sustainability Status

Biomass: The 2008 biomass of Gulf of Alaska pollock – Western/Central is estimated to be at 64% of the biomass needed to support maximum sustainable yield (B_MSY); the Eastern Bering Sea stock is 75% of B_MSY; and the Aleutian Islands stock is 86% above B_MSY.
Overfishing: No
Overfished: No
Fishing and habitat: Midwater trawl nets, which have minimal impacts on the ocean environment, are used to harvest Alaska pollock.
Bycatch: Bycatch is minimal.
Aquaculture: There is currently no aquaculture production of pollock in the U.S.

Science and Management

Alaska pollock, also known as walleye pollock, is a member of the cod family. Pollock is managed as part of a group of species referred to as groundfish multi-species complex under the Groundfish Fishery Management Plans (FMPs) for the Gulf of Alaska and the Bering Sea/Aleutian Islands. Management is divided into two regions, Bering Sea/Aleutian Islands (BSAI) and Gulf of Alaska (GOA). Within the BSAI, there are three stocks, or groups, identified for management purposes: 1) eastern Bering Sea; 2) Aleutian Islands; and 3) Bogoslof. Within the GOA, there are 2 stocks: Eastern and Western/Central. The two fisheries are managed separately but in close connection with one another. The FMPs include management measures such as permitting requirements, limits on the number of fishermen participating in the fishery, quotas, fishing seasons, gear type restrictions, area closings, bycatch minimization, reporting requirements, and observer monitoring. The State of Alaska has jurisdiction over fishermen operating in state waters. There are special management measures in both the federal and state fisheries to reduce competition between fishing and protection of endangered Steller sea lions.

Alaska pollock stocks also occur in international waters, where no country has sole control. The Convention on the Conservation and Management of Pollock Resources in the Central Bering Sea is responsible for the conservation, management, and optimum utilization of pollock resources in the high seas area of the Bering Sea. The pollock resources in the Convention Area collapsed in the early 1990s. Member states (China, Japan, Korea, Poland, Russia, and the United States) have maintained a moratorium on commercial pollock fishing in the Convention Area since 1993 in an effort to allow the stocks to rebuild. Despite the moratorium, pollock stocks in international areas remain in poor condition. The U.S. continues to promote and support international conservation management where unregulated fishing has historically led to declines in the amount of pollock.

Life History and Habitat

Life history, including information on the habitat, growth, feeding, and reproduction of a species, is important because it affects how a fishery is managed. Fast-growing, short-lived species usually respond to management measures more quickly than slow-growing, long-lived species. Alaska pollock mature by age 4, so each generation replaces aging or harvested fish in just a few years. As a result, fisheries managers can alter fishing regulations and, subsequently, offset natural and human induced fluctuations in pollock biomass more quickly than for slower-growing fish.

• Geographic range: Throughout the North Pacific with the largest concentration in the Bering Sea
• Habitat: Pollock are a mid-water to bottom dwelling fish usually found between 328 to 984 feet depths but have been found up to 3,280 feet deep.
• Life span: Up to 17 years
• Food: Juveniles feed on plankton (tiny floating plants and animals); older fish feed mainly on other fish.
• Growth rate: Relatively fast growing
• Maximum size: Up to 3.3 feet in length
• Reaches reproductive maturity: Between the ages of 3 and 4
• Reproduction: Pollock have high fecundity, or potential reproductive capacity - female pollock can produce more than 2 million eggs over the course of several weeks.
• Spawning season: February through April
• Spawning grounds: Aleutian Basin, Bering Sea, Gulf of Alaska, northwest of the Pribilof Islands, and the Strait of Georgia
• Migrations: Pollock migrate seasonally from spawning grounds to feeding grounds.
• Predators: Predators include fish and marine mammals, specifically Steller sea lions.
• Commercial or recreational interest: Commercial
• Distinguishing characteristics: Speckled coloring helps pollock blend in with the sea floor to avoid predators.

Role in the Ecosystem

Pollock are a keystone species, meaning numerous species rely on them for survival; they are an important prey species for Steller sea lions and other marine mammal species as well as foraging fish and seabirds.

Additional Information

Market names: Pollock, Alaska pollock
Vernacular names: Walleye pollock, Pacific pollock

Biomass

Biomass refers to the amount of pollock in the ocean. Scientists cannot collect and weigh every single fish to determine biomass, so they use mathematical models to estimate it using a variety of scientific observer and research vessel data. These estimates evaluate whether a stock is being fished too heavily or if it may be able to tolerate more fishing pressure. Managers can then make appropriate changes to the fishing regulations. Pollock biomass is variable and the increases and decreases are thought to be affected by natural environmental conditions and fishing pressure.

Spawning biomass, rather than total biomass, is shown in the graph. Spawning biomass represents the amount of females in the pollock stock that can reproduce. Management measures for the pollock fishery are geared toward conservation of spawning biomass to ensure that reproductive potential remains at acceptable levels to ensure sustainability.

Landings

Landings refer to the amount of catch that is brought to land. When the U.S. extended its fisheries management jurisdiction out to 200 miles offshore in 1976, U.S. fishermen or processors were not engaged in the Alaska pollock fishery. Initially, the U.S. allowed foreign-flag fishing and fish processing vessels to harvest and process "surplus" pollock. By the late 1980s, U.S. fishermen and processors fully phased out foreign fleets. For over 30 years, the U.S. has maintained safe harvest levels for Alaska pollock, and the fishery is now the largest whitefish fishery in the world. The fishery averages 2.5 billion pounds (1.1 million metric tons) in annual landings and is valued at nearly $1.0 billion.

Note: The landings presented are domestic commercial landings.

Biomass and Landings

Are landings and biomass related? Landings are heavily dependent on available biomass, management measures in the fishery, and fishing effort. Sometimes landings increase when biomass increases; but, depending on how much the landings increase, biomass may fall, as seen between 1984 and 1990. Due to the influence of factors such as fishing pressure and natural variability, this relationship is not always apparent.

Data sources:
Biomass from 2008 Eastern Bering Sea Walleye Pollock Assessment, 2008 Gulf of Alaska Walleye Pollock Assessment

Landings from NOAA's National Marine Fisheries Service (NMFS) Annual Commercial Landing Statistics Website using "POLLOCK, WALLEYE" as species and "ALL STATES"

Important Dates

1970s-80s – Fishing fleet is primarily foreign
1976 – U.S. extends fisheries management authority to 200 miles but allows "surplus" pollock to be caught by foreign fishing fleets operating under agreement within the U.S. zone
1978 – Gulf of Alaska (GOA) Groundfish Fishery Management Plan (FMP)implemented
1982 – Bering Sea/Aleutian Islands (BSAI) Groundfish FMP implemented
1988 – U.S. fishing and fish processing capacity is sufficient to complete the phase out of foreign fleets fishing for pollock in U.S. waters
1992 – Spatial and temporal management measures implemented to protect Steller sea lions; for example, areas around sea lion rookeries closed to pollock fishing during breeding and birthing season
1992 – Bogoslof Region in BSAI closed to directed pollock fishery
1994 – The U.S. and Russia lead effort to conclude a multi-lateral treaty to regulate fishing for pollock in international waters beyond the fishery management zones of the U.S. and Russia. The Convention on the Conservation and Management of Pollock Resources in the Central Bering Sea places a moratorium on pollock fishing until fish stocks in international waters are robust enough to allow for harvests.
1998 – "Improved Retention/Improved Utilization" program implemented, requiring that pollock caught must be kept even if not the targeted species and unintentional catches are counted towards the total allowable pollock catch
1998 – Congress passes the American Fisheries Act (AFA), facilitating the formation of fish harvesting cooperatives that have resulted in numerous conservation benefits, including resolving issues of fishing overcapacity.
1999 – Aleutian Island region closed due to concerns with Steller sea lion recovery
2000 – Standards added to FMPs based on vessel size, type, and ownership to regulate pollock cooperatives, ensuring consistency with American Fisheries Act of 1998
2005 – Aleutian Islands Region reopened, but under constraint of a total allowable catch that cannot exceed 19,000 tons
2008 – Eastern Bering Sea stock drops below the B_MSY level due to a period of below-average recruitments (from 2001-2005); the near-term outlook should be improving due to survey observations of above-average recruitment from the pollock born in 2006

Notes and Links

General Information:
Because Alaska pollock is an important fishery in Alaska, NOAA Alaska Fisheries Science Center has extensive research programs for this fish.

North Pacific Fishery Management Council Groundfish of the Bering Sea and Aleutian Islands (BSAI): Species Profile (2001)

North Pacific Fishery Management Council Groundfish of the Gulf of Alaska: A Species Profile (1998)

Chinook Salmon Bycatch Environmental Impact Statement

Fishery Management:
North Pacific Fishery Management Council Fishery Management Plan for Groundfish of the Bering Sea and Aleutian Islands Management Area (2005)

North Pacific Fishery Management Council Fishery Management Plan for Groundfish of the Gulf of Alaska (2006)

Stock Assessments:
2008 Eastern Bering Sea Walleye Pollock Assessment

2008 Gulf of Alaska Walleye Pollock Assessment

2008 Aleutian Islands Region Pollock Stock Assessment

2008 Abbreviated Assessment of Pollock from the Bogoslof Island Region