Alaska Pollock (Theragra chalcogramma)

• Alaska pollock population levels were estimated to be below target levels in 2009. No overfishing is occurring.
• Harvest limits for the Alaska pollock fishery are adjusted according to pollock population and other factors such as the 2 million ton overall groundfish catch limit for the eastern Bering Sea and Aleutian Islands regions. Catches are closely monitored by scientifically trained observers to ensure that limits of pollock (and other bycatch species) are effective.
• Alaska pollock is high in protein and low in carbohydrates and fat. For more information, see Nutrition Facts. (USDA)
• The Alaska pollock fishery is the largest U.S. fishery by volume. Annual catches from 2000-2009 have averaged 2.9 billion pounds (around 1.3 million metric tons).

Sustainability Status

Biomass: In 2009, the biomass of eastern Bering Sea pollock was estimated to be at 62% of the target level. In the Gulf of Alaska the pollock stock was estimated to be at 66% of the target level.
Overfishing: No
Overfished: No
Fishing and habitat: Midwater trawl nets, which have less impact on the ocean environment than other trawl gear, are used to harvest Alaska pollock.
Bycatch: Bycatch of other species is generally between 1 and 2% of the total Alaska pollock catch; from 2003 through 2008 about 28 pounds of other species were caught for each metric ton (2,205 pounds) of pollock. Pacific salmon bycatch is a particular concern because of the importance of salmon for commercial and subsistence fisheries (note that Pacific salmon bycatch is recorded and where feasible, donated to local Alaska food banks). The North Pacific Fishery Management Council recently developed a new program for bycatch management that includes a lower limit on the incidental catch of Chinook salmon allowed in the pollock fishery. This program was developed from alternatives analyzed in an environmental impact statement and includes performance measures to ensure that individual vessel operators act to minimize bycatch. The Council plans to take similar action to reduce bycatch of other salmon species.
Aquaculture: There is currently no aquaculture production of pollock in the United States.

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 the 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 region. Within the GOA, there are two stocks: Western/Central and Eastern (no trawling is allowed in the eastern GOA). 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 closures, 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 protect endangered Steller sea lions and their critical habitat.

Alaska pollock 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 declined to very low levels by 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 stock to rebuild. Despite the moratorium, pollock abundance in international areas remains at low levels. The United States continues to promote and support these international conservation measures.

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. Pollock are fast-growing and relatively short-lived and thus generally more productive compared to slow-growing, long-lived species. Alaska pollock generally mature by age 4, so each generation replaces aging or harvested fish in just a few years. Pollock are also susceptible to conditions affecting early-life survival (namely predation, environmental conditions, and food availability). For a variety of reasons, pollock’s survival rate in early life stages is highly variable. This can cause wide fluctuations in biomass in a matter of a few years.

• 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. Pollock tend to form large schools and inhabit the mid-water region as adolescents and young adults. Older pollock (>age 5) are thought to be more demersal and reside near the bottom.
• Life span: Up to 17 years
• Food: Juveniles feed on zooplankton and small fish (commonly other smaller pollock); 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 seafloor 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 statistics and mathematical models to provide estimates. The information used includes data collected by scientific observers on fishing boats and by researchers onboard dedicated survey vessels. The estimates are used to evaluate whether a stock is being fished at appropriate levels to ensure sustainability. Managers consider the estimates (and the uncertainty of the estimates) in setting future catch limits. Pollock biomass is variable, and the increases and decreases are thought to be affected by natural environmental conditions and fishing.

Female spawning biomass (as a measure of reproductive capacity) is shown in the graph. Management measures for the pollock fishery are geared toward conservation of this spawning biomass to ensure sustainability. In the eastern Bering Sea, pollock spawning biomass is currently estimated to be below target levels but is projected to increase and be above target levels by 2012. In the Gulf of Alaska, spawning biomass is also below target levels but is projected to increase in 2010.

Landings

Landings refer to the amount of catch that is brought to land (however for pollock, the figures here represent total catch, not just landings; bycatch of pollock in other fisheries is counted against the catch limits). When the United States 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 United States allowed foreign-flag fishing and fish processing vessels to harvest and process "surplus" pollock. By the late 1980s, U.S. fishermen and processors fully harvested available pollock quotas and foreign fleets were phased out. For over 30 years, the United States has maintained safe harvest levels for Alaska pollock, and the fishery is now the largest whitefish fishery in the world. The majority of the U.S. catch of pollock comes from the Bering Sea. From 1977-2009 the catch of eastern Bering Sea pollock has averaged 1.18 million tons. Since 2001, the average has been above 1.33 million tons. However, the average 2008 and 2009 catch has dropped to 0.903 million tons due to stock declines and resulting reductions in allowable harvest rates.

Biomass and Landings

Biomass and landings data can sometimes be used to detect trends in a fishery. They may influence each other, and factors such as changes in management measures, fishing effort, market preferences, or environmental conditions may impact landings and biomass as well.

Data sources:
Biomass and landings from 2009 Eastern Bering Sea Walleye Pollock Assessment, 2009 Gulf of Alaska Walleye Pollock Assessment

Important Dates

1970s-80s – Fishing fleet is primarily foreign
1976 – United States 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. fishery conservation 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 United States and Russia lead effort to conclude a multi-lateral treaty to regulate fishing for pollock in international waters beyond the fishery management zones of both countries. 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 subarea 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 subarea reopened, but under constraint of a total allowable catch that cannot exceed 19,000 tons
2008 – Eastern Bering Sea stock drops below the biomass level that would produce maximum sustainable yield (B_MSY) 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 Fisheries Service 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:
2009 Eastern Bering Sea Walleye Pollock Assessment

2009 Gulf of Alaska Walleye Pollock Assessment

2009 Aleutian Islands Region Pollock Stock Assessment

2009 Assessment of Pollock from the Bogoslof Island Region

Page last updated: January 12, 2010