Ken Tiffan, Ian Jezorek, Russell Perry

U.S. Geological Survey, 5501A Cook-Underwood Rd., Cook, WA 98605

We conducted a field study to evaluate the growth and survival of age-0 Oncorhynchus mykiss implanted with 8-mm PIT tags. A total of 351 PIT tagged fish and 340 control fish (marked with pelvic fin clips) were released, but recapture rates were low, particularly for control fish. Growth in length and mass did not differ between small (42–54 mm) and large (55–64 mm) PIT tagged fish. There was a slightly positive, but weak, relation between tag burden and growth in mass; however, there was considerable variability in this relation (R2 = 0.115). Summer to autumn joint probability of fish surviving and remaining in the study area estimated with a Bayesian mark-recapture model ranged from 0.228 to 0.478 in study streams. We found no significant relation between tag burden and survival, suggesting neither tag burden nor fish size at tagging affected survival.