Data and code from: Spatially-explicit foraging by an apex predator linked to nearshore prey and their accessibility in lakes

Habitat coupling – where mobile predators forage over broad spatial scales
and, in doing so, link food webs from semi-discrete habitat patches – has
emerged as a major structuring force in lake ecosystems. For the
cold-water apex predator lake trout (Salvelinus namaycush), food-web
structure and morphometry-driven accessibility to nearshore areas in
summer strongly determine the degree of littoral-pelagic habitat coupling
across lakes. Much of the evidence for habitat coupling, however, is based
on stable isotopes of carbon to estimate littoral energy acquisition,
whereas spatial data directly linking fish movements and foraging
behaviour in lakes, on which this theory is based – are limited. Here we
estimated nearshore prey abundance at sites of different thermal
accessibility and collected stomach content data, which we combined with
three-dimensional acoustic telemetry positioning and acceleration data to
directly measure the spatial location of summer foraging movements and
habitat coupling by lake trout in lakes with and without an offshore prey
fish. Both study lakes contained higher abundances of nearshore prey fish
at the most thermally accessible (i.e., steep) sites monitored. Nearshore
occupancy accounted for a small proportion of lake trout positions in both
lakes (<5%), although prey fish were present in most (72%) diets
sampled. High acceleration events indicative of foraging were concentrated
in steep, thermally accessible nearshore areas in the lake where offshore
forage fish were absent, but were located further offshore in the lake
with offshore prey fish. We directly demonstrate that habitat coupling by
a wild, apex predator is driven by habitat and prey accessibility.