A major focus of the recently enacted Bipartisan Infrastructure Framework (BIF) is the reconnection of habitat and improving fish passage, vital for all fishes but particularly important for highly migratory species like salmon, steelhead, paddlefish, and sturgeon.
A recent report by a group of researchers quantifies the amount of lost and inaccessible habitat for Pacific salmon in Canada’s Fraser River, one of the most important spawning and rearing grounds for Pacific salmon in British Columbia. The report finds salmon have lost access to as much as 85 per cent of their historical floodplain habitat due to dikes and similar man-made infrastructure.
The research paper, “Quantifying lost and inaccessible habitat for Pacific salmon in Canada’s Lower Fraser River,” published in Ecosphere, further finds that comparing habitat accessibility and barrier density against the assessed status of populations reveals insights useful for understanding the impact of barriers on spawning and rearing and guiding the allocation of restoration effort. Applying methods for addressing missing data, such as lost streams and unmapped barriers, was essential for estimating the accessibility of habitat within a historical context.
The report also observed that while much emphasis has been placed on the role of marine conditions in wild Pacific salmon recovery, the magnitude of habitat loss in the Fraser River cannot be ignored and suggests it is a major driver of observed salmon declines.
The Research: Finn, R. J. R., Chalifour, L., Gergel, S. E., Hinch, S. G., Scott, D. C., and Martin, T. G.. 2021. Quantifying lost and inaccessible habitat for Pacific salmon in Canada’s Lower Fraser River. Ecosphere 12 (7):e03646.