Intracoelomic Acoustic Tagging of Juvenile Sockeye Salmon: Swimming Performance, Survival, and Postsurgical Wound Healing in Freshwater and during a Transition to Seawater

Abstract

Juvenile hatchery-reared Sockeye Salmon Oncorhynchus nerka from Cultus Lake, British Columbia, were implanted during their smolt phase with one of three sizes of dummy acoustic tags to assess how tag burden (tag mass: body mass ratios ranging from 1.3% to 13.6% in air) influenced prolonged swimming performance, survival, and postsurgical wound healing in freshwater for up to 16.5 d and following a transition to seawater for 9 d. Tagged fish were compared with surgical shams and control fish (no tag, no surgery). Fish subjected to sham surgery treatments had mean swim times similar to those of control fish; however, tagged fish had a significantly lower probability of swimming the mean time of nontagged control fish. In addition, we found that the effect of tagging on swimming performance was exacerbated by tag burden and that higher tag burdens decreased the swimming performance of tagged individuals. Fish with tag burdens ≥8% had shorter swimming durations than fish with tag burdens <8%. The incisions of fish implanted with smaller tags healed more quickly than those of fish implanted with the largest tag. Overall, survival was high (≥95%) and in freshwater mortalities only occurred in fish that had tag burdens greater than 6%. These findings have important implications for studies using tagging technologies to examine the behavior and survival of migrating salmon smolts.

Received October 13, 2011; accepted October 22, 2012

ACKNOWLEDGMENTS

We thank the Cultus Lake Sockeye Salmon Recovery Team for providing access to fish; A. Stobbart and Inch Creek hatchery staff for rearing fish; B. Gillespie for manufacturing the dummy tags; A. Lotto for laboratory construction, maintenance and fish care; J. Richards for additional laboratory space; and J. Burt, R. Dhillon, M. Donaldson, M. Drenner, E. Eliason, M. Gale, A. Haas, K. Jeffries, E. Martins for laboratory assistance. T. Kozak and D. Schluter provided statistical advice, and M. Beaks and C. Phillis provided analysis and graphics assistance. Both A.L.C. and T.D.C. were supported by and research funds provided through a National Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant to SGH and NSERC Strategic Partnership Grant through the Ocean Telemetry Network Canada to S.G.H. and S.J.C.