Analysis of straying variation in Alaskan hatchery chinook salmon (Oncorhynchus tshawytscha) following transplantation

In 1976 chinook salmon (Oncorhynchus tshawytscha) gametes from the Chickami n and Unuk rivers in southeastern Alaska were transplanted 250 km to establ ish hatchery runs at Little Port Waiter (LPW), Baranof Island. From 1977 to 1989, 1 862 058 marked smelts from 12 broods were released from LPW. Womin g and straying were estimated from adult recoveries at 25 locations in Alas ka and British Columbia between 1981 and 1989. Of 22 198 LPW fish recovered over this period, 21 934 (98.8%) were collected at LPW. Of 264 fish recove red elsewhere, 38.3% were within 7 km of LPW; 64.4% were within 25 km of LP W. No LPW fish were recovered from the ancestral rivers, but nine fish were recovered from rivers supporting wild chinook salmon. Straying declined wi th distance from the release site but varied between hatcheries and streams . Straying declined with increasing age and run size. Straying was similar between the populations but varied among broods, and analysis of straying i n experimental groups provided evidence for a heritable component. Males st rayed more often than females. Population, gender, run size, and recovery a ge interacted to produce substantial variation in straying, indicating that run composition can produce complex straying responses.