March 22, 2007
Commercial and sport fishery catches in 2006 in Southeast Alaska included 3,600 Chinook salmon that originated from NOAA Fisheries research at Little Port Walter, according to tags returned to scientists by both sport and commercial fishermen.
"Research projects at Little Port Walter are having significant positive impacts on Chinook salmon fisheries in Southeast Alaska," said Bill Heard, who leads the Marine Salmon Interactions studies at the Alaska Fisheries Science Center's Auke Bay Laboratory in Juneau. "While the main purpose of various projects is to improve scientific understanding of how best to use stocking techniques in hatchery programs that minimize adverse impacts on wild stocks, an added bonus of this research is the contributions made to local fisheries."
Each year tagged juvenile Chinook salmon from various studies are released at Little Port Walter. They spend from two to five years in the ocean before maturing and returning to the station.
"While some of these fish are caught in fisheries every year, 2006 was an exceptional year with much larger than normal contributions to regional fisheries," said Heard. "Noteworthy was the large number of Little Port Walter Chinook salmon caught in the Juneau sport fishery during the Golden North Salmon Derby last August. Of the 514 Chinook salmon landed in the derby, 63--or 12 percent--were from Little Port Walter. This likely was the highest single source contribution of Chinook salmon to the [Juneau] derby."
The Juneau derby area is roughly 130 nautical miles from Little Port Walter.
Additionally, Little Port Walter fish represented a large percentage of all coded wire tagged Chinook salmon recovered in Southeast Alaska commercial fisheries in 2006. Catch rates for Little Port Walter fish were as high as 25% during particular commercial troll and net fisheries. Such high rates of recovery suggest high ocean survival conditions for at least two release groups of juveniles. This notion was validated with the return of 2,800 maturing Chinook salmon to Little Port Walter last July and August. Older fish from the same release groups will likely be caught or returned next year.
NOAA scientists are now analyzing tags from released groups to determine overall marine survival rates.
Little Port Walter research involves two stocks of introduced Chinook salmon maintained at the Baranof Island station after eggs were transplanted there in 1976 from Chickamin and Unuk Rivers on the Southeast mainland. There are no naturally spawning stocks of Chinook salmon within 90 miles of Little Port Walter. The two introduced stocks are kept discrete from each other by tagging all juveniles with coded wires before release, then collecting tags from returning adults and separating the returned adults into the two different stocks before they are spawned.
Studies of Chinook salmon include brood stock development, enhancement technologies, genetic and behavioral differences in stocks, hatchery domestication, migration timing, ocean distribution patterns, and ability to contribute to fisheries.
Recently studies have focused on hatchery-wild stock interaction by comparing biological characteristics of the two stocks after six or seven generations in Little Port Walter's experimental hatchery with wild cohorts from the original founder populations.
One of the more important features scientists look for is marine survival of juveniles released for maximizing exploitation of hatchery stocks. Under Pacific Salmon Treaty accords between the U. S. and Canada most of Alaska's hatchery produced Chinook salmon does not count against catch limits or treaty quotes set between the two countries.
Little Port Walter, operated by Auke Bay Laboratory of the Alaska Fisheries Science Center, is the oldest year-round biological field station in Alaska where initial studies on Alaska's marine resources began in 1933.
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