Short-term evaluation of visible implant alpha tags in juveniles of three fish species under laboratory conditions.

Visible implant alpha (VI alpha) tag-induced changes in mortality and condition, as well as tag retention and readability, were examined during a 4-week period for juveniles of three fish species: tiger muskellunge Esox masquinongy × Esox lucius (91 ± 7 mm total length, L(T), mean ± s.d.), Snake River cutthroat trout Oncorhynchus clarki behnkei (84 ± 8 mm) and rainbow trout Oncorhynchus mykiss (85 ± 5 mm). Mortality and condition did not differ between tagged fish and control fish for any species and overall tag retention rates were high (92% for E. masquinongy × E. lucius, 91% for O. c. behnkei and 100% for O. mykiss). Short-term readability of VI alpha tags was low in juvenile E. masquinongy × E. lucius and juvenile O. c. behnkei. Therefore, it is not recommend to use VI alpha tags in juvenile E. masquinongy × E. lucius or juvenile O. c. behnkei for periods >2 weeks, but VI alpha tags seem to be suitable for juvenile O. mykiss for a period of at least 4 weeks.