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Description:
Alaska Pollock (Theragra chalcogramma)

Council:
North Pacific Fishery Management Council

Related Links
http://www.fakr.noaa.gov/npfmc/
http://www.afsc.noaa.gov/species/pollock.php
http://stellersealions.noaa.gov/

Pollock

A common thread linking marine predators in western Alaska is their reliance on walleye pollock (Theragra chalcogramma), a prolific hake-like member of the cod family whose range extends across the North Pacific Rim from Puget Sound to the Sea of Japan. Pollock's central importance as a forage fish in the Bering Sea food web has been known since the 19th century, hence pollock's scientific name, Theragra, from the Greek Ther = beast, agra = prey or food.1 Pollock is widely consumed at every stage of its life cycle by mammals, birds and fishes.

Pollock is the dominant fish prey in the eastern Bering Sea,2 and pollock was the dominant prey fish of groundfish and Steller sea lions in the Gulf of Alaska during the 1990s.3 Groundfish predators of pollock include some of the most abundant and most highly valued species in the Bering Sea and Gulf of Alaska, in addition to adult pollock: Pacific halibut, Greenland turbot, arrowtooth flounder, flathead sole, Pacific cod, and sablefish, as well as Pacific sandfish, shortspine thornyhead, great sculpin, and Alaska skate.4 Major marine mammal predators of pollock include the endangered Steller sea lion, depleted northern fur seal, depleted Pacific harbor seal, spotted and ribbon seals in the Bering Sea, as well as harbor and Dall's porpoises, fin, minke and humpback whales.5 Seabird predators of pollock include some world's largest nesting colonies of kittiwakes, murres, and puffins in the Pacific Ocean, in addition to fulmars, guillemots, cormorants, shearwaters, murrelets and auklets.

Fishery
Long regarded as a commercially worthless "scrap" fish by American fishermen who targeted salmon, halibut, herring and crab, pollock�s potential as a cheap and plentiful protein source was only realized in the early 1960s when Japanese factory trawlers introduced a process for reducing pollock's white flesh into a protein paste called surimi. In the 1990s, as cod stocks in the North Atlantic collapsed from overfishing, pollock became a popular whitefish substitute for cod in the global seafood trade. Today pollock is widely marketed in Asia, Europe and North America as surimi (imitation crabmeat), fast food fish fillets and frozen fish sticks, in addition to a highly lucrative market for pollock roe (fish eggs).

The scale of the modern pollock fishery has no historical precedent in the region, with recent catches of ~1.5 million metric tons/year (3.3 billion pounds) � representing 70-75% of the annual Bering Sea groundfish catch and nearly one-third of all marine fish caught in U.S. waters annually. Pollock has accounted for over 70% of all groundfish landings off Alaska since the 1960s (~52 million tons, more than 114 billion pounds),6 and another 20 million tons of pollock have been taken from adjacent international waters of the central Bering Sea (Donut Hole) and Russian waters off Cape Navarin, northwestern Bering Sea.

While fishery officials point proudly to the enormous yields and revenues generated by the Alaska pollock fishery as proof of its sustainability, the National Research Council recognized nearly a decade ago that several regions where pollock were once abundant have been heavily exploited and the pollock stocks in those regions have suffered major declines (NRC 1996).7 Intense concentration of the pollock fisheries on spawning aggregations since the 1980s has been accompanied by serial declines in pollock abundance in the Gulf of Alaska (1980s), Bogoslof/Aleutian Basin (1987-1992), and Aleutian Islands (1990s), leading to the closure of the latter two areas in the 1990s. Overall yields have remained high throughout the period of U.S. management, but three of the four defined "stocks" in the fishery management plans (FMPs) remain at or near historic low abundance levels today. With the Aleutian Basin and Aleutian Islands closed to directed pollock fishing due to low abundance, and the Gulf of Alaska experiencing historic low pollock abundance and lower TAC levels, fully 96% of all pollock caught off Alaska are now taken from the eastern Bering Sea.

Management Issues
While fishery officials point to the enormous yields and revenues generated by the Alaska pollock fishery as proof of its sustainability, the National Research Council recognized nearly a decade ago that several regions where pollock were once abundant have been heavily exploited and the pollock stocks in those regions have suffered major declines (NRC 1996). Intense concentration of the pollock fisheries on spawning aggregations since the 1980s has been accompanied by serial declines in pollock abundance in the Gulf of Alaska (1980s), Bogoslof/Aleutian Basin (1987-1992), and Aleutian Islands (1990s), leading to the closure of the latter two areas in the 1990s. Overall yields have remained high throughout the period of U.S. management, but three of the four defined "stocks" in the fishery management plans (FMPs) remain at or near historic low abundance levels today. The Aleutian Basin and Aleutian Islands stocks are closed to directed pollock fishing due to low abundance, and the Gulf of Alaska is experiencing historic low pollock abundance. Thus, fully 96% of all pollock caught off Alaska are now taken from the eastern Bering Sea.

The impacts of these trends on pollock predators in the ecosystem could be devastating. In 1998 and again in 2000, NMFS prepared legally required Endangered Species Act Section 7 Biological Opinions on the pollock fisheries in which the agency concluded that the intense spatial and temporal concentration of the pollock fisheries within designated critical habitat jeopardizes Steller sea lions and adversely modifies sea lion critical habitat, the most important feature of which is the prey field. But the effects on sea lions (and other pollock predators) of the fishery catch levels were not considered directly then and remain unaddressed today.

The abundance of Bering Sea pollock has declined steadily since 2003 under intense fishing pressure and is now estimated to be at the lowest level since 1980, when the stock was recovering from the first wave of foreign trawling during the 1970s. The projected 2008 Bering Sea pollock abundance will be the lowest in the history of the U.S.-managed fishery, and the proposed 2008 fishery quota of 1 million tons (2.2 billion pounds) could drive the stock to collapse. Given the risk of a fishery catastrophe and ecological havoc caused by the loss of the most important forage fish off Alaska, NMFS should require a far more precautionary approach.

1 Jordan, D.S., and B.W. Evermann. The fishes of North and Middle America: a descriptive catalogue of the species of fish-like vertebrates found in the waters of North America north of the Isthmus of Panama. Bull. U.S. Natl. Mus. No. 47, 1898.
2 National Marine Fisheries Service. Alaska Groundfish Fisheries Programmatic Supplemental EIS on the Fishery Management Plans of the Bering Sea/Aleutian Islands and Gulf of Alaska (2001, 2003, 2004). Laevastu and Larkins (1981) estimated that annual pollock consumption by marine mammals in the eastern Bering Sea was comparable to the commercial catch. Using data from 1985-1988, Livingston (1993) estimated total groundfish consumption of eastern Bering Sea pollock ranging from 3.86 million metric tons in 1985 (following the appearance of a large 1984 year class) to 920,000 metric tons in 1988.
3 M-S. Yang and M.W. Nelson. Food Habits of the Commercially Importance Groundfishes in the Gulf of Alaska in 1990, 1993, and 1996. NOAA Tech. Memo. NMFS-AFSC-112. February 2000. See also: E. H. Sinclair and T.K. Zeppelin. Seasonal and Spatial Differences in Diet in the Western Stock of Steller Sea Lions (Eumetopias jubatus). Journal of Mammalogy, 83(4): 973-990, 2002.
4 National Marine Fisheries Service. Alaska Groundfish Fisheries Programmatic Supplemental EIS on the Fishery Management Plans of the Bering Sea/Aleutian Islands and Gulf of Alaska (2001, 2003, 2004).
5 National Marine Fisheries Service. Alaska Groundfish Fisheries Programmatic Supplemental EIS on the Fishery Management Plans of the Bering Sea/Aleutian Islands and Gulf of Alaska (2001, 2003, 2004).
6 Since the late 1950s, when the first factory fishing ships of the distant water nations appeared off the coast of Alaska, approximately 74 million metric tons (163 billion pounds) of walleye pollock, Pacific cod, yellowfin sole, rock sole, Greenland turbot, rockfish and other species have been reported as catch in the eastern Bering Sea, west-central Gulf of Alaska, and Aleutian Islands, not including incidental bycatch of non-target species before 1990. Total does not include catches of halibut, salmon, herring, crab and shrimp, which are managed separately.
7 National Research Council. The Bering Sea Ecosystem. National Academy Press (1996): p. 212-213.


 
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