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> November 2001
Hatcheries have not replaced wild salmon stocks in Alaska's Prince William Sound
JUNEAU, AlaskaSalmon hatcheries in Alaska's Prince William Sound have not contributed to the decline in the region's wild salmon stocks, according to a group of state, University of Alaska and federal biologists.
In an article recently published in the Transactions of the American Fisheries Society (Volume 130 pp 712720), four veteran Alaska salmon biologists show that recent wild salmon declines in the sound are not easily attributed to hatchery production.
Authors of the article are: Alex Wertheimer and William Heard of the U.S. NOAA Fisheries Auke Bay Laboratory, William Smoker of the University of Alaska Fairbanks School of Fisheries and Ocean Sciences, and Timothy Joyce of the Alaska Department of Fish and Game, Cordova Alaska.
Transactions is the premier peer-refereed science journal of North America's fisheries science profession.
The authors analyzed historical salmon catch data to show that after hatcheries became important, total salmon production in Prince William Sound has increased to a greater degre than it has in other regions, indicating a large benefit from hatcheries for the harvest. They show that even after recent declines since the mid-1980s, the productivity of wild stocks in Prince William Sound remained among the highest in Alaska.
The sound's salmon hatcheries have added 1823 million salmon to the annual harvest of wild salmon caught each year in the 1990s, the researchers said.
The researchers found that apparent declines of wild pink salmon spawning stocks after 1990 were not caused by ecological displacement by hatchery salmon. Instead the declines were related to increasing accuracy of fishery managers who each year control the fishery so as to allow enough spawners to reach the spawning streams. In early years the managers tended to err on the cautious side, closing the fishery and allowing more fish into the streams than their 'escapement goal' required. In recent years, with better techniques, managers have been able to increase the harvest while still meeting the escapement goal. The apparent decrease of escapement counts is a in large part a consequence of more and more accurate management.
They found that while it is possible that declines of marine survival of pink salmon fry in Prince William Sound could have been a consequence of ecological interactions with fry produced by hatcheries, it is more likely that changes of food supply or of predators have been responsible.
Their findings refute research done by other scientists that found that hatchery-produced salmon have essentially replaced the sound's wild stocks.
SFOS > News > Releases > November 2001
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