Potential Impacts of Pacific Salmon (Oncorhynchus spp.) Hatcheries on Pacific Herring (Clupea pallasii) in Lynn Canal

Authors: Tyler Houseweart, Seth Brickey, Elise Christey, Sam Kurland, and Martina Miller

This paper was written as part of the 2011 Alaska Oceans Sciences Bowl high school competition. The conclusions in this report are solely those of the student authors.

Abstract

The Lynn Canal Pacific herring (Clupea pallasii) population declined rapidly between 1971 and 1981, for reasons not completely understood. The population has not rebounded, and the Lynn Canal herring fishery has remained closed since 1982. It is unusual for herring populations to remain depressed for this length of time in the absence of a fishery. This suggests the presence of factors that are preventing the resurgence of the herring population. A number of possible factors have been hypothesized, including disease, increased predation by marine mammals, anthropogenic noise pollution, marine pollution, and habitat degradation. We discuss each of these hypotheses in turn, and suggest the presence of an additional factor. We hypothesize that a factor acting to keep the Lynn Canal herring population depressed is predation by, and competition with, Pacific salmon (Oncorhynchus spp.) released from the Douglas Island Pink and Chum Macaulay salmon hatchery. We discuss the Lynn Canal ecosystem and the role of herring within it; herring are key component of the Lynn Canal food web. Therefore, it would be beneficial to the ecosystem if the population were to rebound. To that end, we establish a management plan. We present relevant background information pertaining to management, including information on herring fisheries, salmon fisheries, and the Douglas Island Pink and Chum hatchery. We propose that research be conducted to identify reasons why the population remains depressed, including the extent to which salmon compete with and prey upon Lynn Canal herring. We also recommend the establishment of a task force to discuss research findings and provide recommendations to the Alaska Department of Fish and Game and the Alaska Board of Fisheries. The goal of our recommendations is to facilitate a recovery of the Lynn Canal herring population and develop an ecosystem-based, multispecies approach to the management of the Lynn Canal.

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