Understanding the impact of Alaska Peninsula fisheries on Yukon Kuskokwim salmon

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Central to the Arctic-Yukon-Kuskokwim (AYK) chum salmon conservation problem is identifying at what stage of the life cycle the salmon fail to survive. Harvested by bycatch fisheries in Alaskan seas and bays, either at the sub-adult stage or when the adults finally make their way home. This final stage gets a lot of attention, especially as his AYK Chum traverses his 1,200-mile Aleutian line. His June Alaska Peninsula fishing around South Unimak Island represents a very small geographic portion of the AYK Chum migration. Looking at these stages of life, the National Oceanic and Atmospheric Administration and the Alaska Fish and Game Research Service provide important data on the health and mortality of these chum throughout their life cycle.

Salmon survival during the adult migration stage of the life cycle, which is important to so many communities across Alaska, depends on understanding several scientific terms. This ‘stock composition’ and ‘yield rate’ terminology is used in genetic analysis of mixed stock fisheries and can blind people. So, in its simplest terms, catch rate shows the impact of a particular fishery on total operations, whereas stock composition is a snapshot limited to a particular time and region, representing a percentage of total operations. It is not a thing.

The AYK region and the adjacent Bristol Bay and Norton Sound Cham stocks are identified as a single genetic stock: the Coastal West Alaska (CWAK) stock group. In 2007-2009, the Western Alaska Salmon Stock Identification Program (WASSIP) used innovative genetic techniques to uniquely identify a stock group spanning Korea to Oregon. This study informed analyzes of stock composition and yield rates at the time, but also remains important for identifying bycatch of prohibited species by trawls and for informing ongoing marine salmon research.

WASSIP years showed median yields of 2.1%, 3.6%, and 6.9% for the CWAK stock in the June salmon fishery in the Southern Alaska Peninsula. Yield rate corresponds to the percentage of runs. The total population of the CWAK stock is determined by adding the estimated runoff of each river system from Bristol Bay to Norton Sound to the yields in Bristol Bay, the Northern Peninsula and Area M. The 2007 population (catch + runoff) was 8.5 million friends. Dividing the June 2007 chum harvest in Area M by 8.5 million chum yields a yield or run rate of 2.1%.

In contrast, resource composition is the percentage of harvest over a given period and area. To put this more concretely, a 1-week fishery harvested of 20,000 chum of 11,400 CWAK stock would have a composition of 57% CWAK. However, this one component does not define the percentage of the overall run. His AYK Cham run from 2007 to 2009 was strong, with Asian Cham stocks relatively low unlike recent years when Asian stocks have been fairly high.

Given the above, even if AYK assumes the most generous catch of salmon passing through the M area from the available data, it is not due to catch rates in the M area. As scientists have observed, mortality factors such as poor marine rearing conditions, scarcity of catches, and low energy reserves contribute far more to low productivity of chum salmon in the CWAK than catch rates in the Alaska Peninsula. is a big factor in While it may be tempting to blame one region’s catch for another region’s low profitability, science does not support that argument, and biologists at NOAA and Fish and Game have also endorsed that conclusion. maintain.

Steve Raifenstuhl is a retired salmon biologist with 45 years of experience in Alaska. He continues to study salmon harvest data and marine surveys throughout Alaska.

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