Evaluation of Visible Implant Tags Applied to Wild Coastal Cutthroat Trout and Dolly Varden in Margaret Lake, Southeast Alaska

Abstract

Abstract Visible implant tags were injected into nonanadromous coastal cutthroat trout Oncorhynchus clarki clarki and Dolly Varden Salvelinus malma during field sampling in 1990 and 1991. We report the rate of tag retention for a population of wild cutthroat trout and Dolly Varden. Estimates of tag retention can be used to adjust potential bias in estimates of survival, mortality, and abundance resulting from unaccounted tag loss. We consider the effects of size and some of the causes for tag loss. Cutthroat trout retained 95% of the tags after 17 months; Dolly Varden retained 89% of the tags after 17 months (as determined by Robson–Reiger model estimates). Difference in tag loss between the two species was significant (P < 0.05) when tested with binary logistic regression methods. When tested separately in the model, the effect of fish length on tag loss was significant for Dolly Varden but not for cutthroat trout. The experience of the individual applying the tags appeared to affect retention; however, ...