Fine-scale behaviour of walleye (Sander vitreus) on a spawning shoal in Hamilton Harbour, Ontario

Re-establishment of a naturally reproducing walleye (Sander vitreus) population is a management objective for Hamilton Harbour, western Lake Ontario. Though mature, stocked walleye have been captured during the spawning period on littoral shoals of the harbour, there is no evidence of natural recruitment. Fine-scale walleye positions derived from acoustic telemetry data on a known spawning shoal were aggregated into discrete, presumptive spawning events, where spawning conditions (e.g., Distance to Shore, Movement Rate), timing (e.g., Photoperiod), and their spatio-temporal distribution (e.g., Duration, Kernel Density Estimates) were described. A selection of these metrics were used to characterize seven unique spawning behaviours ranging from spatially focused nearshore events that are consistent with previously described spawning behaviour to short and fast transitory events. The location of some spawning events aligned with areas of high egg deposition, but additional events were found to be deeper and further offshore than expected, but still consistent with other Great Lakes populations. Confirmation of egg deposition at these deeper locations is required as it may indicate a potential remediation measure (i.e., addition of aggregate materials at these depths). The range of behaviours observed is indicative of both individual variation and differential habitat preference for the spawning shoal.