Relative Survival of Unmarked and Fin-Clipped Coho Salmon from Bear Lake, Alaska

Abstract

Abstract Some of the completely censused smolts of coho salmon (Oncorhynchus kisutch) emigrating from Bear Lake, Alaska, during the years 1967–1969 and 1977–1989 received a variety of fin clips: left and right ventral clips, adipose clips (with and without coded wire tags), and combinations thereof. Coho salmon adults returning to Bear Lake were censused and examined for missing fins. As measured by the return rates of unmarked and fin-clipped coho salmon, fish that had received ventral fin clips as smolts suffered significantly higher mortality than did unmarked fish. In contrast, fish that had received adipose fin clips and implanted coded wire tags did not exhibit significantly higher mortality than unmarked fish.