PNNL

Abstract

This study examined the influence of surgical implantation of an acoustic transmitter on the swimming performance, growth, and survival of juvenile sockeye salmon (Oncorhynchus nerka) and fall Chinook salmon (O. tshawytscha). The transmitter weighed 0.72g in air and the fish weighed 6 to 23 g. Mean critical swimming speeds for fall Chinook salmon ranged from 47.5 to 51.2 cm s-1 (4.34 to 4.69 body lengths [BL] s-1) and did not differ among tagged, untagged and sham-tagged groups. Tagged sockeye salmon, however, did have lower Ucrit than control or sham fish. The mean Ucrit for tagged sockeye salmon was 46.1 cm s-1 (4.1 BL s-1) which was approximately 5% less than the mean Ucrit for control and sham fish (both groups were 48.6 cm s-1 or 4.3 BL s-1). There was no difference in length or weight among treatments (control, sham, tag) either at the start or the end of the test period suggesting that implantation did not negatively influence the growth of either species. None of the sockeye salmon died from the influence of surgical implantation of transmitters. In contrast, we did find that the 21-d survival differed between tagged and control groups of fall Chinook salmon although this result was confounded by the poor health of fall Chinook salmon treatment groups.