Evaluation of a Sterile-Male Release Technique: A Case Study of Invasive Sea Lamprey Control in a Tributary of the Laurentian Great Lakes

Invasive species can have detrimental impacts on native species and ecosystem services for humans. A technique that involves sterilization and release of males into wild populations of the same species can be useful in the control of invasive or pest species. A sterile-male release technique (SMRT) was used on a novel vertebrate system, the invasive Sea Lamprey Petromyzon marinus in the Great Lakes, in an attempt to control population size. Sea Lamprey populations in the Great Lakes have been suppressed since the 1950s by (1) pesticide applications to kill larvae in streams and (2) barriers to block upstream spawning migrations. Here, we present a literature review and meta-analysis of the SMRT by using a case study from the St. Marys River, where the SMRT was applied as an experimental method of Sea Lamprey control from 1991 to 2011. Observations obtained from the St. Marys River during and after SMRT application were used to evaluate whether the SMRT was effective at suppressing reproduction. Males were successfully sterilized and exhibited normal mating behaviors. The survival of embryos in nests was lower during the years when the SMRT was applied (32%) than during the post-SMRT period (67%). The overall distribution of embryo viability in the river shifted after the SMRT was applied. During the SMRT application period, the observed ratios of sterile males to normal (fertile) males on nests were significantly different than expected, possibly due to an underestimation of adult Sea Lamprey abundance in the St. Marys River. Even at lower sterile male : normal male ratios, the number of viable embryos produced would have declined, but the level of reproductive suppression required to overcome recruitment variability was unclear. We discuss the effectiveness of the SMRT as it pertains to the Sea Lamprey, and we highlight difficulties in data interpretation and provide future direction for similar control programs. Received December 1, 2015; accepted June 16, 2016 Published online August 31, 2016