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EVALUATION OF POST-SMRT EMBRYO VIABILITY IN THE ST. MARYS RIVER
Gale Bravener1, Jessica Barber2, Lisa Walter2
1Fisheries and Oceans Canada, Sea Lamprey Control Centre, 1219 Queen Street East, Sault Ste. Marie, ON. P6A 6N5
2Marquette Biological Station, U.S. Fish and Wildlife Service, 3090 Wright Street, Marquette, MI. 49855
3Great Lakes Fishery Commission, 2100 Commonwealth Blvd., Suite 100, Ann Arbor, MI. 48105
A sterile male release technique (SMRT), an alternative method for controlling sea lampreys, was implemented in the St. Marys River during 1991-2011 but concurrent treatments with the lampricide granular Bayluscide largely confounded evaluation of the technique during implementation. One evaluation technique was assessment of sea lamprey nest success (egg viability) in the St. Marys River rapids, which quantified the reduction in survival at egg stage attributed to SMRT since embryos were not affected by granular Bayluscide treatments. In this study, we conducted nest evaluations for four years after SMRT was discontinued (2012-2015) using the same methods used when SMRT was operational to test whether the post-SMRT embryo viabilities were higher than embryo viabilities when SMRT was ongoing. We found that the post-SMRT viabilities were significantly higher, suggesting that the original baseline viability of 43.4% noted by Bergstedt et al. (2003) may have been underestimated. This study provides evidence that SMRT was likely reducing recruitment to the larval stage in the St. Marys River, and corroborates previous work showing that SMRT is effective at reducing reproduction. However, we did not take into account the magnitude of the effect, nor the cost effectiveness of SMRT compared to other control methods.