Habitat overlap of juvenile and adult lake trout of Great Bear Lake: Evidence for lack of a predation gradient?

Louise Chavarie; Kim L Howland; Les N. Harris; Michael J. Hansen; C P Gallagher; W J Harford; W M Tonn; Andrew M. Muir; Charles C. Krueger

doi:10.1111/eff.12470

USGS · 70202006

Habitat overlap of juvenile and adult lake trout of Great Bear Lake: Evidence for lack of a predation gradient?

Louise Chavarie·Kim L Howland·Les N. Harris·Michael J. Hansen·C P Gallagher·W J Harford·W M Tonn·Andrew M. Muir·Charles C. Krueger

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Abstract

A range of organisms, from plankton to fish, commonly shift their habitat distributions horizontally or vertically due to predation risk. Juvenile lake trout, Salvelinus namaycush , are generally viewed as occupying deep areas of lakes to decrease predation pressure from adults. In contrast, we found that juvenile lake trout from Great Bear Lake, NT, Canada, occupied a variety of habitats and from shallow to deep depths (0–150 m), overlapping with adult lake trout. No evidence occurred for a length depth‐based segregation (e.g., ontogenetic shift). Genetic variation was also similar among juveniles in the different depth zones. However, isotopic niches and C:N ratios among juveniles showed some variability in niche widths and positions for individuals caught from the 51–150 m zone compared to juvenile individuals caught from 0–20 m and 21–50 m zones. The uniformly distributed adult lake trout in Great Bear Lake may evenly distribute predation pressure (including cannibalism) across shallow‐ and deep‐water habitats more than in other lakes. As a result, juveniles may respond to differences in foraging opportunities rather than predation risks. Juvenile lake trout did not appear to conform to the general pattern of juveniles seeking a deep‐water refuge to reduce predation risks. In contrast, juvenile lake trout of Great Bear Lake displayed broad resource use across all depths and habitats.

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Source-reported bounding extent: 64.48226107017604° to 67.40748724648756° latitude; -125.98022460937499° to -116.53198242187499° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Louise Chavarie, Kim L Howland, Les N. Harris, Michael J. Hansen, C P Gallagher, W J Harford, W M Tonn, Andrew M. Muir, Charles C. Krueger. 2019-02-12. Habitat overlap of juvenile and adult lake trout of Great Bear Lake: Evidence for lack of a predation gradient?. https://doi.org/10.1111/eff.12470

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