physical habitat associations of fish species in the kivalliq region of nunavut, canada
abstract
the canadian arctic and subarctic (areas north of 60° latitude) support distinct
aquatic environments governed by the unique geomorphology and climate of the region.
historically, fish and fish habitat impacted by development activities in this region have
been assessed using literature derived from southern populations. using these
assumptions from southern populations on environmental impact assessments for
northern regions may not accurately capture differences in physical fish habitat
associations. to better characterize northern habitat associations for use in northern
environmental assessments, this study sought to achieve three objectives. first, to
determine patterns in the depth of occupancy of a model species, lake trout, using two
databases in canada, comparing northern and southern regions. second, to provide an
assessment of freshwater fish habitat associations in 11 species specific to the kivalliq
region of nunavut. finally, where feasible, to develop habitat suitability indices (hsi)
with northern-specific data based on these associations. to achieve these goals, a novel
method of estimating depth-of-occurrence was developed and applied to an analysis of
standardized fish capture data from both arctic and ontario (southern) lakes. habitat
association data sourced from populations north of 60° was then used to develop
evidence-based arctic-specific hsi values for comparison to the existing habitat
ecosystem assessment toolkit (heat) model. depth-of-occurrence analysis indicated
significant differences in the abundance of lake trout between northern and southern
regions, but not significant differences in habitat associations with depth. however, the
results of hsi analysis integrating information from several peer-reviewed studies
indicated significant differences in depth patterns across latitude for both lake trout and burbot; both species had stronger associations with depth in ontario (southern) lakes
across three life stages (adult/juvenile, young-of-the-year and egg/spawning) relative to
the arctic, suggesting that depth may indeed more strongly shape habitat associations in
southern vs. northern populations. no other species had sufficient data to facilitate
quantitative analysis, however, qualitative descriptions of northern habitat associations
were summarized where feasible. conclusions from this study demonstrate potential
differences in fish habitat associations between northern and southern regions but a larger
sample size of lakes will be required north of 60° latitude to make a determination.
region-specific habitat association models are recommended, along with increased
observations and study of fish-habitat associations in the north, as this study highlights
many data gaps that exist for several species in establishing hsi models specific to arctic
freshwater fishes in the arctic.