Theragra chalcogramma (Pallas, 1814)
The Alaska pollock or walleye pollock (Gadus chalcogrammus, formerly Theragra chalcogramma) is a marine fish species of the cod family Gadidae. Alaska pollock is a semipelagic schooling fish widely distributed in the North Pacific with largest concentrations found in the eastern Bering Sea.
While belonging to the same family as the Atlantic pollock, the Alaska pollock is not a member of the same Pollachius genus. Alaska pollock was long put in its own genus Theragra, but more recent research has shown it is rather closely related to the Atlantic cod and should be moved back to genus Gadus in which it was originally described. Furthermore, Norwegian pollock (Theragra finnmarchica), a rare fish of Norwegian waters, is likely the same species as the Alaska pollock.
Ecology and behaviour
The speckled colouring of Alaska pollock makes it more difficult for predators to see them when they are near sandy ocean floors. They are a relatively fast growing and short-lived species, currently representing a major biological component of the Bering Sea ecosystem. It has been found that catches of Alaska pollock go up three years after stormy summers. The storms stir up nutrients, and this results in phytoplankton being plentiful for longer, which in turn allows more pollock hatchlings to survive. Alaska pollock has well-developed drumming muscles that the fish use to produce sounds during courtship like many other gadids.
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The Alaska pollock has been said to be "the largest remaining source of palatable fish in the world." Around 3 million tons of Alaska pollock are caught each year in the North Pacific from Alaska to northern Japan. Alaska pollock is the world's second most important fish species in terms of total catch.
Alaska pollock catches from U.S. fisheries have been quite consistent at about 1.5 million tons a year, almost all of it from the Bering Sea. Information on the current stock status for Alaska groundfish is updated annually, whereas the specific 2007 pollock assessment is also available. The Alaska pollock landings are the largest of any single fish species in the U.S. However, in each of the last three years, the pollock population has declined; in 2008, it fell 38 percent and it was worried that the 2008 pollock catch will be the lowest in 30 years. Although the fishery has been hailed as an example of good management, and the Marine Stewardship Council declared it "sustainable", Greenpeace has criticized its management for many years and placed pollock on its international "red list" of endangered fish. In response to the new data, Greenpeace called for 2009 catch levels to be reduced to half those of 2008 to avoid further long-term declines.
This decline has led some scientists [according to whom?] to worry that Alaska pollock could be about to repeat the kind of collapse experienced by Atlantic cod, which could have negative consequences for the world food supply and the entire Bering Sea ecosystem. Halibut, salmon, endangered Steller sea lions, fur seals, and humpback whales all eat pollock and rely on healthy populations to sustain themselves.
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Compared with pollock, Alaska pollock has a milder taste, whiter color and lower oil content.
High quality, single frozen whole Alaska pollock fillets may be layered into a block mold and deep frozen to produce fish blocks that are used throughout Europe and North America as the raw material for high quality breaded and battered fish products. Lower quality, double-frozen fillets or minced trim pieces may also be frozen in block forms and used as raw material for lower quality, low-cost breaded and battered fish sticks and portions.
Single frozen Alaska pollock is considered to be the premier raw material for surimi; the most common use of surimi in the United States is "imitation crabmeat" (also known as crab stick).
Alaska pollock is commonly used in the fast food industry, in products such as McDonald's Filet-O-Fish sandwich and (now discontinued) Fish McBites, Arby's Classic Fish sandwich, Long John Silver's Baja Fish Taco, and Birds Eye's Fish Fingers in Crispy Batter.
- Eschmeyer, W. (2015) chalcogrammus, Gadus Catalog of Fishes, Calicornia Academy of Sciences, accessed 5 June 2015)
- "Walleye Pollock Research". Alaska Fisheries Science Center. NOAA. 2013. Retrieved 9 April 2015.
- Byrkjedal, I.; Rees, D. J.; Christiansen, Jørgen S.; Fevolden, Svein-Erik (2008-10-01). "The taxonomic status of Theragra finnmarchica Koefoed, 1956 (Teleostei: Gadidae): perspectives from morphological and molecular data". Journal of Fish Biology 73 (5): 1183–1200. doi:10.1111/j.1095-8649.2008.01958.x.
- Carr, Steven M.; Marshall, H. Dawn (2008). "Phylogeographic analysis of complete mtDNA genomes from walleye pollock (Gadus chalcogrammus Pallas, 1811) shows an ancient origin of genetic biodiversity". Mitochondrial DNA 19 (6): 490–496. doi:10.1080/19401730802570942. Retrieved 2012-03-24.
- Ursvik, Anita; Breines, Ragna; Christiansen, Jørgen S.; Fevolden, Svein-Erik; Coucheron, Dag H.; Johansen, Steinar D. "A mitogenomic approach to the taxonomy of pollocks: Theragra chalcogramma and T. finnmarchica represent one single species". BMC Evolutionary Biology 7 (1): 86. doi:10.1186/1471-2148-7-86.
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- Hawkins, A. D.; Rasmussen, K. J. (1978). "The calls of gadoid fish". Journal of the Marine Biological Association of the United Kingdom 58: 891–911. doi:10.1017/s0025315400056848.
- Yong-Seok Park; Yasunori Sakurai; Tohru Mukai; Kohji Iida; Noritatsu Sano (2004). "Sound production related to the reproductive behavior of captive walleye pollack Theragra chalcogramma (Pallas)". Nippon Suisan Gakkaishi (in Japanese and with an English abstract) 60: 467–472.
- Skjæraasen, Jon Egil; Meager, Justin J.; Heino, Mikko (2012). "Secondary sexual characteristics in codfishes (Gadidae) in relation to sound production, habitat use and social behaviour". Marine Biology Research (Taylor & Francis) 8 (3): 201–209. doi:10.1080/17451000.2011.637562. Retrieved 9 April 2015.
- Theragra chalcogramma (Pallas, 1811) FAO, Species Fact Sheet. Retrieved April 2012.
- Clover, Charles (2004). The End of the Line: How Overfishing Is Changing the World and What We Eat. Ebury Press. ISBN 0-09-189780-7.
- FAO (Food and Agriculture Organization of the United Nations) (2010). The State of World Fisheries and Aquaculture 2010. Rome: FAO. ISBN 978-92-5-106675-1.
- Bernton, Hal. "Business & Technology | Seattle trawlers may face new limits on pollock fishery | Seattle Times Newspaper". Seattletimes.nwsource.com. Retrieved 2012-04-25.
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- "World's Largest Food Fishery in Danger of Collapse". Greenpeace. 2008-10-09. Retrieved 2012-04-25.
- "Rethinking Sustainability - A new paradigm for fisheries management" (PDF). greenpeace.org. March 2006. Retrieved 2013-09-14.
- Tepper, Rachel (24 January 2013). "McDonald's Sustainable Fish: All U.S. Locations To Serve MSC-Certified Seafood". Huffington Post. Retrieved 9 April 2015.
- "Classic Fish". Arby's. 2014. Retrieved 9 April 2015.
- "Ingredient Statements" (PDF). Long John Silver's. June 2014. Retrieved 9 April 2015.
- "Fish Fingers in Crispy Batter". Birds Eye. 2014. Retrieved 9 April 2015.
- NOAA NMFS: U.S. Seafood Facts
- FISHINFOnetwork Market Report 04/07
- FishBase: Alaska Pollock
- Alaska pollock-Theragra chalcogramma fishery profiles Status of these fisheries, summarised on FisheriesWiki