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Diel and spatial movement patterns of downstream migrating sea lamprey transformers
1USGS, Great Lakes Science Center, Hammond Bay Biological Station, 11188 Ray Road, Millersburg, MI 49759
2Rubenstein School of Environment and Natural Resources, University of Vermont, 308 D Aiken Center, 81 Carrigan Dr., Burlington VT 05405
We determined CPUE for downstream migrating juvenile Sea Lamprey using both drift and fyke nets fished both laterally across and vertically within the stream channel of two tributaries to Lake Champlain to describe spatial distribution. Spatial distribution was correlated with discharge, in some cases matching the stream discharge nearly exactly while in other cases spatial distribution suggested some behavioral component with selection for stream regions with higher water velocity. We demonstrated that newly metamorphosed, juvenile Sea Lamprey can be successfully implanted with 12 mm HDX PIT tags which allows for easier tracking in the field compared to other tagging options. Survival of tagged individuals was not significantly different from control groups with over 90% survival across all lamprey tagged and tag retention was high. We were able to use that tagging technique to conduct a long term behavioral observation study in an artificial stream and describe how Sea Lamprey activity follows a distinct diel pattern. We also observed timing of downstream movement in-stream under natural conditions to validate the results of the artificial stream study. The in-stream observations correspond with the activity patterns described from the artificial stream with most downstream movement occurring within a few hours of dark and diminishing through the night.