A habitat lifeline for juvenile salmon in the Fraser River
Apr 16, 2024|inBlog, Climate Adaptation Series, Salmon Steward
A unique solution to reverse decades of marsh degradation in the Fraser River estuary and improve habitat for juvenile salmon.
This story originally appeared in the Spring 2024 edition of Salmon Steward, the Pacific Salmon Foundation’s quarterly print magazine.
Sturgeon Bank — a stretch of the Fraser River delta located off the west coast of Richmond, British Columbia — has lost at least 160 hectares of tidal marsh habitat over the last three decades due to dredging, dikes, and other human interventions.
This has resulted in significant marsh recession along the Fraser River delta, which is critical habitat for hundreds of millions of out-migrating juvenile salmon, including endangered Fraser Chinook, as well as coho, sockeye, and steelhead.
An innovative multi-year project led by Ducks Unlimited Canada (DUC) aims to rehabilitate the tidal marsh habitat that juvenile salmon depend on as they prepare to transition from freshwater conditions to life in the ocean.
For tidal marshes to thrive, a continuous supply of sediment deposition is needed to allow vegetation to grow — a natural process that has been drastically reduced by human activities. This has converted productive marshes into mudflats that are not suitable habitat for fish and other wildlife.
DUC is depositing re-purposed sediments along the Sturgeon Bank foreshore to mimic natural sedimentation processes in partnership with Fisheries and Oceans Canada, the Province of British Columbia, Raincoast Conservation Foundation, Tsawwassen First Nation, and the Lower Fraser Fisheries Alliance.
“We’ve been studying this marsh recession for more than a decade and looking for inspiration to address this challenge. Given the massive scale of ecological loss, we need to locally customize the restoration solution and test it on a pilot scale to understand the response of the foreshore to this innovative method of sediment addition,” says Eric Balke, senior biologist with DUC and project lead of the Sturgeon Bank Sediment Enhancement Pilot Project.
PSF provided approximately $275,000 in time-sensitive funding to the Sturgeon Bank project in February 2024 to help DUC and partners complete a significant amount of sediment addition.
Since 2023, DUC and partners have added 15,000 cubic metres of sediment to Sturgeon Bank. This volume is comparable to six Olympic swimming pools. It’s no easy feat to transport such a high volume of sediment.
DUC and partners used a temporary kilometre-long pipeline to transport a slurry of water and sediment to the foreshore. Waves, tides, and currents distribute these nourishing sediments across the Sturgeon Bank tidal flats over time.
The project repurposes sediments that were already dredged from the Fraser River to decrease marine navigation congestion. These sediments are typically discarded in the ocean, but DUC’s unique habitat rehabilitation project effectively diverts them from being dumped into the Strait of Georgia.
“With this innovative project we are trying to supply the ecosystem with the sediment it needs to remain resilient,” says Balke.
The sediment addition at Sturgeon Bank addresses habitat loss for salmon and birds, and supports coastal flood protection for the City of Richmond by mitigating the effects of rising sea levels.
The long-term plan of the project is to continue adding sediment to the Sturgeon Bank foreshore over the next decade while tracking the progress of marsh recovery.
“The short-term success of this pilot will show the feasibility of this method in adding sediment to Sturgeon Bank to support tidal marsh restoration. In the long term, we would like to potentially scale up the project and apply the concept more broadly across the Fraser River delta,” says Balke.
The Sturgeon Bank project received support from the British Columbia Salmon Restoration and Innovation Fund, jointly funded by Government of Canada and the Province of British Columbia. PSF is proud to support this game-changing habitat project. Additional funding for this project was provided by Tsawwassen First Nation, the Vancouver Fraser Port Authority, and the Nature Force.
