A management-scale investigation of consistent individual differences in behaviour and trapping bias in sea lamprey (Petromyzon marinus)

The sea lamprey (Petromyzon marinus) is invasive in the Laurentian Great Lakes. Trapping in large rivers could suppress sea lamprey recruitment by removing migrating adults prior to spawning. Currently, the proportion of sea lamprey trapped (efficiency) is too low for control purposes, possibly because trapping is biased toward certain behavioural types. We tested if individual differences in time to enter a novel environment (risk-taking) and proportion of time moving (activity) under standardized laboratory conditions were correlated with time to encounter and enter a trap in the field. 638 sea lamprey were tagged, assessed for risk-taking and activity in sequential trials, and released in the river to be trapped. In the laboratory, individuals differed consistently in risk-taking and activity behaviours, and more active individuals entered a simulated trap sooner than less active individuals. In the field, however, the times to first trap encounter, and capture in a trap, were not correlated with risk-taking or activity. Our study provides a novel demonstration of how patterns from small-scale behavioural studies may not extend to management-scale applications.