Differential Performance of Ventral Fin Clipped and Adipose Fin Clipped/Coded-Wire-Tagged Spring Chinook Salmon at Warm Springs National Fish Hatchery, Oregon

Warm Springs National Fish Hatchery is operated by the U.S. Fish and Wildlife Service, and is located on the Warm Springs River within the Confederated Tribes of the Warm Springs

Reservation of Oregon. For three brood years (1987-89), we applied ventral fin clips and adipose fin clips/coded-wire tags in order to evaluate the two marks on hatchery performance of spring Chinook salmon (Oncorhynchus tshawytscha). Each brood year, approximately 100,000 fish received a ventral fin clip and 100,000 were marked with an adipose fin clip/coded-wire tag. For the 100,000 ventral fin clipped fish, 50,000 received a left ventral fin clip and 50,000 received a right ventral fin clip. The mark study was also nested within a diet study, where fish in ponds containing left ventral fin clips were fed one diet and fish in ponds containing right ventral fin clips were fed another diet. From our sampling at the hatchery, we found that: 1) each mark group within a diet had variable length frequency distributions at release; 2) age, length, and sex composition at return were similar for each marked group within a diet; and 3) survival to adult was affected by diet but not by type of mark. In closing, spring Chinook salmon marked with a ventral fin clip performed as well as fish marked with an adipose fin clip/coded-wire tag; but sample sizes were small and survival to adult

was low for all groups.