Food web position of burbot relative to lake trout, northern pike, and lake whitefish in four sub-Arctic boreal lakes

Abstract

Summary We assessed the food web position of burbot Lota lota relative to co-occurring large-bodied fishes in four northern (62°40′N, 114°10′W) boreal shield lakes of similar size (305–547 ha) using a stable isotope approach. Trophic position (inferred from δ15N) was positively correlated to body mass in burbot, lake trout Salvelinus namaycush, and northern pike Esox lucius, but negatively correlated to body mass in lake whitefish Coregonus clupeaformis. Carbon source (inferred from δ13C) was positively correlated to body mass in lake whitefish, but not related to body mass in any of the other three species. In all lakes, burbot had δ15N and δ13C signatures very similar to those of lake trout. Both burbot and lake trout were more δ15N-enriched than northern pike (P < 0.001). Lake trout had lower δ13C than northern pike and lake whitefish (P = 0.0023) but not burbot. Our results confirm that burbot occupy a position near the top of the food chain in boreal lakes and may play an important role in structuring the limnetic fish community.