Using Acoustic Telemetry to Evaluate Performance of Sea Lamprey Traps in the Great Lakes

Improved trapping methods are desired for population assessment and control of invasive Sea Lamprey, Petromyzon marinus, in the Great Lakes. Acoustic telemetry was used to determine exploitation rates (i.e., fractions of the adult sea lamprey population removed by traps) at two upstream trapping locations in the St. Marys River, the connecting channel between lakes Superior and Huron. Telemetry receivers throughout the drainage allowed trap performance (exploitation rate) to be partitioned into two components: proportion of Sea Lampreys that visited traps (availability) and proportion of available Sea Lampreys that were caught (local trap efficiency). Estimated exploitation rates for adult Sea Lampreys were well below those needed to provide population control in the absence of lampricides. Local trap efficiency and availability estimates suggest that substantial increases in catch would require major changes to Sea Lamprey trapping systems. Lower-than-expected local trap efficiency estimates also suggest that traditional assessment methods underestimate adult Sea Lamprey abundance in the St. Marys River. Results from this study highlighted the need to evaluate even the most basic of mark-recapture assumptions and demonstrated how bias associated with telemetry tags can be estimated and incorporated in models to improve inferences about parameters that are directly relevant to fishery management.