Fine-Scale Pathways Used By Adult Sea Lampreys during Riverine Spawning Migrations

Abstract

Better knowledge of upstream migratory patterns of spawning Sea Lampreys Petromyzon marinus, an invasive species in the Great Lakes, is needed to improve trapping for population control and assessment. Although trapping of adult Sea Lampreys provides the basis for estimates of lake-wide abundance that are used to evaluate the Sea Lamprey control program, traps have only been operated at dams due to insufficient knowledge of Sea Lamprey behavior in unobstructed channels. Acoustic telemetry and radiotelemetry were used to obtain movement tracks for 23 Sea Lampreys in 2008 and 18 Sea Lampreys in 2009 at two locations in the Mississagi River, Ontario. Cabled hydrophone arrays provided two-dimensional geographic positions from acoustic transmitters at 3-s intervals; depth-encoded radio tag detections provided depths. Upstream movements occurred at dusk or during the night (2015–0318 hours). Sea Lampreys were closely associated with the river bottom and showed some preference to move near banks in shallow glide habitats, suggesting that bottom-oriented gears could selectively target adult Sea Lampreys in some habitats. However, Sea Lampreys were broadly distributed across the river channel, suggesting that the capture efficiency of nets and traps in open channels would depend heavily on the proportion of the channel width covered. Lack of vertical movements into the water column may have reflected lamprey preference for low water velocities, suggesting that energy conservation was more beneficial for lampreys than was vertical searching in rivers. Improved understanding of Sea Lamprey movement will assist in the development of improved capture strategies for their assessment and control in the Great Lakes.

Received September 12, 2014; accepted February 6, 2015

ACKNOWLEDGMENTS

This study was funded by the Great Lakes Fishery Commission's Sea Lamprey Research Program. We thank Robert Pierre of Iron Bridge, Ontario, for access to his land, Aaron Blake, U.S. Geological Survey, for providing BathMapper software and technical support, Scott Evans, U.S. Geological Survey, for assistance with radiotelemetry, Scott Brewer, U.S. Geological Survey, for processing acoustic telemetry data, and Rod McDonald, Gale Bravener, and Joe Hodgson, Fisheries and Oceans Canada, and Erick Larson and Mike Lancewicz, U.S. Geological Survey, for technical assistance. Scott Miehls, Andrew Muir, Matthew Faust, and three anonymous reviews reviewers provided valuable comments on an earlier version of this manuscript. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. This manuscript is contribution number 14 of the Great Lakes Acoustic Telemetry Observation System (www.data.glos.us/glatos) and contribution number 1918 of the U.S. Geological Survey, Great Lakes Science Center.