North American Journal of Fisheries Management: Vol. 21, No. 1, pp.
255–260.
B. A. Berejikian and E. P. Tezak
National Marine Fisheries Service, Northwest Fisheries Science Center, Resource Enhancement and Utilization Technologies Division, Manchester Research Station, Post Office Box 130, Manchester, Washington 98353, USA
S. L. Schroder
Washington Department of Fish and Wildlife, 600 Capitol Way North, Olympia, Washington 98501, USA
Received February 14, 2000; accepted August 8, 2000
Abstract.—Release of captively reared adults is one of several strategies currently being used to maintain imperiled populations of chinook salmon Oncorhynchus tshawytscha in the Pacific Northwest. This study evaluated the breeding behavior and success of captively reared chinook salmon released at maturity into a controlled-flow stream channel. Female egg deposition was 49.5%, which is much lower than that reported for wild populations, but egg-to-fry survival was 62.5%. Females abandoned 40% of the nests they constructed, and males were often absent during the female's nest construction. The underlying causes of these presumed behavioral deficiencies might have limited the breeding success of the population. The efficacy of adult release strategies should be assessed within the context of other potential release options, keeping in mind the objectives of the individual program. Under current culture practices, the reproductive success of captively reared chinook salmon that are released as adults may be less than that of wild salmon.