Estimating Distant Escapements From Local Fisheries: A Novel Genetic Application for Management Challenges

Genetic stock identification has been used to estimate stock compositions of Southeast Alaska Chinook fisheries since 1999.  However, in addition to providing sound estimates of the annual stock composition, the program also allows for estimation of escapements for certain stock groups harvested in the Southeast Alaska fisheries.  This innovative procedure incorporates data from exploitation rate indicator stocks, frequency of marked fish sampled from a mixed stock fishery, and stock composition estimated from genetic analysis for that same mixed stock fishery.  This method is currently being utilized in Southeast Alaska commercial troll and sport fisheries both to estimate terminal run sizes of stocks of natural and hatchery origin Chinook salmon and to estimate natural escapement of these stocks. These stocks migrate through Southeast Alaska as they return to spawn in distant rivers, often where assessment of the number returning is difficult or unavailable.  Poor stock status in these stock groups has precipitated restrictions in both U.S. and Canadian fisheries managed under the Pacific Salmon Treaty.  The project described herein will allow for improved quality of escapement estimates, and thus improved management of Chinook fisheries.