Temporal and Spatial Habitats of Anadromous Brook Charr in the Laval River and its Estuary

Abstract

Anadromy in brook charr occurs across the species’ range, but few studies have examined contiguous seasonal movements and habitat utilization of freshwater and estuarine environments. We used acoustic telemetry to track movements of anadromous brook charr for 1 year in the Laval River, Quebec. Fish entered the marine environment in May and June, inhabited shallow (<1.7 m), near-shore areas (<500 m from shore), and rarely ventured beyond the headlands of the bay. They were found where salinities were 1–34 ppt and temperatures 5–18°C. There was a strong tidal periodicity to observed movements with fish running up into bays as they became inundated at high tide and then returning to deep river channels in the bays at low tide. Between late July and early September, the charr returned to freshwater and spawned in the middle and upper sections of the river in October and November. Winter habitats were dispersed over 22 km of the river including two lakes. These detailed observations are an important contribution to our understanding of the evolutionary significance of anadromy in this species. The salinity and temperature co-tolerance provides insights into the species’ post-glacial dispersal, present-day distribution, and potential habitat maps for conservation, restoration, and enhancement programmes.