Integrating Acoustic Telemetry and Stable Isotope Data Reveals Overlap in Resource Use by Large‐Bodied Fishes in a Temperate Lake

ABSTRACT Temperate lake ecosystems undergo seasonal shifts that disproportionately alter the availability of suitable habitat for fishes of different thermal guilds. While many studies have investigated fish habitat use patterns, few have estimated the degree to which fish species overlap in space across seasons from a three‐dimensional perspective. Here, we investigated the seasonal timing of habitat overlap and trophic niches of key fish species—burbot ( Lota lota ), lake trout ( Salvelinus namaycush ) and white sucker ( Catostomus commersonii )—in a small boreal lake located in Ontario, Canada. Using a spatial telemetry array and pressure‐sensing transmitters, we collected 2 years of three‐dimensional fish habitat use data, which we paired with stable isotope data (carbon, nitrogen and sulphur) from all trophic levels to distinguish littoral (nearshore), pelagic (offshore) and benthic sources of energy acquisition. Telemetry data analysis showed that three‐dimensional space use and habitat overlap significantly differed across species and were season‐specific, particularly between burbot and lake trout. Stable isotope analysis demonstrated a high reliance upon littoral resources for the three fish species, which generally matched telemetry estimates of nearshore habitat use, apart from the unexpectedly high littoral signature for burbot. Our joint application of acoustic telemetry and stable isotope analysis provided a deeper insight into the spatial and trophic ecology of these important fish species, clarifying how species with seasonal spatial overlap can thrive by relying on different food resources.