Spawning behaviour of lake whitefish in Lake Huron revealed by fine-scale acoustic telemetry and Indigenous ecological knowledge

Lake whitefish (Coregonus clupeaformis) are ecologically, economically, and culturally significant across their range, yet little is documented about the species’ spawning behaviour. Here, we used a VEMCO Positioning System (VPS) and the local ecological knowledge of Saugeen Ojibway Nation in a Two-Eyed Seeing approach to characterize sex-specific movement patterns of lake whitefish at a spawning shoal in Georgian Bay, Lake Huron (Ontario, Canada). In fall 2020, 50 lake whitefish were tagged with acoustic transmitters and 28 of those fish were detected during the deployment of the VPS between 15 October 2021 and 18 January 2022. Occupancy of lake whitefish on the VPS followed a bell-shaped pattern, with an increase, plateau that lasted ∼1 week, and subsequent decrease in activity over a 48-day period demarcating the 2021 spawning season. Apart from 2 resident females, males appeared in the area first. Both sexes moved into shallower lake depths at night and deeper depths during the day. Females moved 18.0% faster than males during the day whereas males moved 39.5% faster than females at night. Depths occupied became shallower over time until the peak activity phase, followed by a transition back to deeper waters. Both sexes used a variety of habitats over the spawning season, including the main spawning shoal, sandy substrates, and steep slopes. These insights on the habitat usage and spawning phenology of lake whitefish provided through our Two-Eyed Seeing approach can help inform stewardship initiatives aimed at increasing recruitment of depleted populations of this important species.