Up to 85 per cent of historical salmon habitat lost in Lower Fraser
region
In order to reverse salmon declines, researchers say, more than 1,200
barriers blocking off streams and habitats need to be removed

Date:
August 5, 2021
Source:
University of British Columbia
Summary:
For perhaps the first time ever, researchers have mapped out the
true extent of habitat loss for salmon in the Lower Fraser River,
one of the most important spawning and rearing grounds for Pacific
salmon in B.C.

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 harbor wildlife -- due
to dikes and similar infrastructure, say researchers.



FULL STORY ==========================================================================
For perhaps the first time ever, researchers have mapped out the true
extent of habitat loss for salmon in the Lower Fraser River, one of the
most important spawning and rearing grounds for Pacific salmon in B.C.


========================================================================== 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.

The results of the study reveal the magnitude of the loss of salmon
habitat in Canada's most productive salmon river, says senior author
Dr. Tara Martin, a professor of forest and conservation sciences at UBC,
and suggests this loss of habitat is a major contributor to current
salmon declines.

"Fraser salmon are being impacted by multiple threats in both their
freshwater and marine habitats," says Dr. Martin.

"If salmon do not have sufficient habitat to breed and complete their
life cycle, then none of the other conservation management actions we take
will matter." In order to come up with their assessments, the researchers studied historical vegetation records, old surveyor and topographical
maps dating back to the 1850s, as well as other records pertaining to
the Lower Fraser-a region that spans 20,203 square kilometers between
Hope and Boundary Bay in South Delta.

"Given the magnitude of habitat loss in the Fraser, large-scale habitat protection and restoration is a key component in efforts to restore
wild populations of salmon to the Lower Fraser," adds Dr. Martin. "We
are using these results to identify priority areas to remove barriers and restore salmon habitat to have the greatest benefits for salmon recovery." ========================================================================== Story Source: Materials provided by University_of_British_Columbia. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Riley J. R. Finn, Lia Chalifour, Sarah E. Gergel, Scott G. Hinch,
David
C. Scott, Tara G. Martin. Quantifying lost and inaccessible habitat
for Pacific salmon in Canada's Lower Fraser River. Ecosphere,
2021; 12 (7) DOI: 10.1002/ecs2.3646 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210805115525.htm

--- up 12 weeks, 6 days, 22 hours, 45 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)