Mixed stock analysis of sublegal Chinook salmon encountered in the Southeast Alaska troll fishery, 2004-2007

Alaska Department of Fish and Game, Fishery Data Series No. 12-34, Anchorage.

Southeast Alaska troll permit holders harvest Chinook salmon originating from Alaska, British Columbia, and the west coast of the United States. Only individuals larger than 711 mm may be retained by fishermen; smaller individuals must be released. These encounters with sublegal-sized Chinook salmon are not recorded and the subsequent mortality is unknown. Beginning in 1998, studies were conducted to estimate the rate at which sublegal-sized Chinook salmon are encountered by this fishery. As part of these studies tissue samples were taken from sublegal-sized individuals for estimation of stock composition using mixed stock analysis with genetic information. The estimation of stock composition of tissue samples taken during 2004–2007 is described in this report. Results indicate that the largest contributors to the annual sublegal harvest are the Southern Southeast, Andrew Creek, East Vancouver Island, West Vancouver Island, Upper Columbia River (Summer/Fall), and Central British Columbia Coast stock groups. When each of the seasonal fisheries was considered the composition was more variable, but the same groups remain important contributors.