In their summary of Canadian research as part of the Canada Country Study, Shuter et al.⁽¹³⁾ identified two main categories of climate change impacts on fish populations: 1) impacts on fish at specific locations, such as changes in productivity or health; and 2) impacts on the spatial distribution of fish populations, such as northward migrations.

The overall projected effects of these changes on sustainable harvests vary across the country, as summarized in Table 2.

Table 2: Projected changes in sustainable harvests in Canada (as summarized in reference 13, a review of literature published prior to 1998)

In general, the researchers found that northern regions were expected to benefit, whereas southern regions could potentially experience decreases in sustainable harvests. This was due primarily to the assumption that colder regions would profit more from longer ice-free periods and warmer growing seasons. Water temperature, however, is not the only factor that must be considered in projecting the impacts of climate change on Canadian fisheries. Increases in extreme events, changes in circulation patterns and sea-lake-river ice regimes, and invasions of exotic species must also be included. The complexity this adds to impact assessments is such that most predictions for the fisheries sector have tended to be qualitative in nature, estimating only whether the impacts will be positive or negative.⁽¹³⁾

Although adaptation has not been extensively examined in the context of climate change, adaptation to changing environmental conditions is not a new concept for the fisheries sector. This sector has adapted to fluctuating environmental conditions and fish abundances in the past, and will continue to do so in the future. Successful adaptation will be enhanced by continuing efforts to develop ecosystem-centred strategies that focus on minimizing the negative impacts of climate change at the local level, strengthening management regimes, and reducing vulnerability to other stresses.