| dc.description.abstract | Identifying differences in movement behaviour and the variance in behavioural
strategies that may exist across a single species occupying a heterogeneous landscape
can provide valuable ecological and evolutionary insights; taking movement
heterogeneity into account in management and conservation efforts may ultimately
improve the sustainability of species with significant economic and ecological value,
such as walleye (Sander vitreus). Lake Winnipeg (Manitoba, Canada) supports the
second largest commercial fishery for walleye in North America. The lake is divided into
two relatively separate basins connected by an intermediate channel, which differ
dramatically in both abiotic and biotic features. Despite this, little is known about
whether (or how) walleye move or use variable habitats throughout the lake.
Historical mark-recapture models from tagged walleye revealed low but
measurable rates (0.3-1.2%) of movement annually between the north and south basins
of Lake Winnipeg. Contemporary estimates using acoustic telemetry data detected a
greater but comparably low rate of transition between the basins annually for walleye
(7-8.5%). Both historical and current models revealed that movement was more likely to
occur in a south to north direction. Additionally, annual survival across both basins of
the lake was higher historically (54%) then it is currently (37%).
To further investigate contemporary patterns of inter-basin movement, I
assessed female walleye tagged across the south. I uncovered repeatable patterns of
individual fish movement, where migratory walleye consistently travelled into the north basin for a period of time, and resident walleye remained within the south basin. I found
that migrants significantly increased home (95%) and core (50%) ranges during the
summer and fall associated with a northern shift in latitudinal distribution. Finally,
putative repeat spawning in the year following tagging appeared to be greater for
migrants (65%) compared to residents (40%). This thesis describes the first formal
description of walleye movement in Lake Winnipeg, and suggests connections between
movement patterns (i.e., migrants and residents) to potential differences in life history
(i.e., differential probability of repeat spawning). Direct movement results presented
here should prove useful to fisheries management and policy for both commercial and
recreational activities across the separately managed basins of Lake Winnipeg. | en_US |
