The priority areas for freshwater fish biodiversity in the Arctic watershed in Ontario.
So instead of looking directly for fish, we decided to work on predicting which fish might be where. To do that, we needed to look at fish habitat – the places that fish need to feed, overwinter and reproduce – which, in turn, depends on climate, topography, freshwater quantity and quality, and connectivity between water bodies. We compiled information on climate, elevation, and hydrology across the Arctic drainage basin and then examined almost a century of scientific fish sampling records, finding as many records as we could that documented where fish species had been caught over the years, to determine species habitat preferences. Finally, we undertook some statistical matchmaking of fish and available habitats to predict where 30 species of freshwater fish were likely to occur across this enormous watery landscape.
The resulting maps gave us a good idea of the watersheds that were likely the most important for freshwater fish. However, we wanted to go a step further, and so we used computer algorithms to identify watersheds that are not only the most important for freshwater fish, but also ones where industrial disturbance was the lowest. Finally, we also factored in connectivity between waterways, an important element for fish that migrate or that need room to respond to climate change. It’s also important because water quality in upstream areas affects downstream areas – it’s all connected. We looked at the places that are the most important for overall biodiversity, then used our algorithms to additionally zero in on four fish species that are culturally and ecologically important – lake sturgeon, brook trout, lake whitefish and walleye.
After all the number crunching, we found that large parts of the Albany River watershed, Severn River watershed, and the headwaters of the Nelson, Winisk and Severn Rivers were important for freshwater fish biodiversity overall, and also for the four focal species. For brook trout – which migrate back and forth from freshwater rivers to Hudson Bay – the Ekwan River watershed was also highlighted as a priority.