**ABSTRACT NOT FOR CITATION WITHOUT AUTHOR PERMISSION. The title, authors, and abstract for this completion report are provided below. For a copy of the full completion report, please contact the author via e-mail at rlmclaugh@uoguelph.ca. Questions? Contact the GLFC via email at frp@glfc.org or via telephone at 734-662-3018.**

 

 

 

Effects of Local Hydrodynamic Conditions and Individual Differences in Behavior on Trap Entrance by Sea Lamprey

 

Robert McLaughlin2, Bill Annable3, Adrienne McLean4, Emelia Myles-Gonzalez5, Rachel Holub2

2 Department of Integrative Biology, University of Guelph, Guelph, ON

N1G 2W1

3 Department of Civil and Environmental Engineering, University of

Waterloo, Waterloo, ON N2L 3G1

4 Fish and Fish Habitat Protection Program, Fisheries and Oceans Canada,

867 Lakeshore Road, Burlington, ON L7S 1A1

5 Tulloch Engineering Inc, 1942 Regent St, Sudbury, ON P3E 5V5

 

 

September 2019

 

ABSTRACT:

 

The Great Lakes Fishery Commissionís Strategic Vision pledges to develop trapping as a viable method to help control Sea Lamprey (Petromyzon marinus). Presently, the proportion of upstream migrating Sea Lamprey captured in traps (trapping efficiency) is too low for control purposes. We proposed to test two hypotheses thatcould explain the lower than desired trapping efficiency: individuals differ consistently in behaviours that affect encounter with, and entrance into, traps such that only a portion of the migration run is vulnerable to trapping (behavioural types hypothesis) and hydrodynamic conditions when lamprey arrive at trap openings varies with time, but entrance into a trap only occurs under a specific subset of hydrodynamic conditions (local hydrodynamics hypothesis). Consistent with the behavioural types hypothesis, in multiple standardized laboratory tests Sea Lamprey differed repeatably (consistently) in measures of risk taking, general activity, and response to a putative predator (chemical) cues, but not in measures of sociability or preference for faster water flow. Contrary to behavioural types hypothesis, however, we found no evidence that the individual differences were related with vulnerability to trapping. The behaviour of trapped lamprey did not differ consistently from animals captured at large downstream of traps (Bowmanville and Duffins Creeks; project years 1+2). Similarly, in field releases of individuals differing in behaviour (St. Marys River; project years 3+4), times to encounter and enter a trap were unrelated to differences in behavioural type. Further investigations suggested the lack of any relationship between vulnerability to trapping and individual differences in behaviour could be due to the erosion of repeatable differences in behaviour while individuals were at large in the field, due to declining energy reserves and changing state of maturation with time spent at large, or to the spatial scale and/or the density of traps, because the predicted relationship between trap vulnerability and Sea Lamprey activity was observed under confined laboratory conditions. The local hydrodynamics hypothesis could not be tested satisfactorily due to challenges with measuring the local conditions at trap openings and, once these challenges were resolved, insufficient numbers of lamprey visiting the trap opening during the period of measurement. However, the prediction that local hydrodynamic conditions vary at the trap openings over time was supported at traps downstream of the Clergue Generating Station in the St. Marys River. An opportunistic investigation tested if the ratio of catches of Sea Lamprey from traps on opposite (north, south) sides of the river changed when discharges from draft tubes exiting the generating station on the north and south sides of the river were altered. No evidence of trap catches correlating with horizontal variation in discharge was obtained. Our findings suggest the lower than desired efficiency of trapping Sea Lamprey cannot be explained by differences in behavioural type, or by horizontal variation in discharge near trap sites, but the importance of temporal variation in local hydrodynamic conditions at trap openings requires further testing.