Salmon have lost access to as much as 85 per cent of their historical floodplain habitat—the biologically rich wetlands next to a river or stream that typically harbour wildlife—due to dikes and similar infrastructure, say researchers at UBC and the Raincoast Conservation Foundation.
“Only around 101 square kilometers out of an estimated 659 square kilometers of historical floodplains remain accessible to salmon,” says lead author Riley Finn, a research associate with the Conservation Decisions Lab in the faculty of forestry at UBC.
“This loss is particularly critical for populations of coho and Chinook, which rely more heavily on these habitats for rearing, compared to other types of salmon,” says Finn.
The team also found that up to 64 per cent of streams are now off-limits to salmon due to in-stream barriers like dams, floodgates and road culverts, blocking off important channels for migrating salmon, which spend part of their lives at sea but return to their natal streams to spawn and rear their young.
According to Finn, there are currently more than 1,200 barriers preventing salmon from accessing approximately 2,224 kilometers of streams.
