In March, a group led by the Raincoast Conservation Foundation created a 30-metre breach in the North Arm Jetty, a seven-kilometre long man-made finger that extends into the Strait of Georgia at the end of the river’s north arm.
Conservationists say the structure forces young salmon into the high deeper, high salinity water of the Georgia Strait before they are ready.
In their juvenile stage, the fish rely on the brackish marsh habitats between the river and the strait to rear and feed before they’re prepared to transition to the ocean.
“They want to be able to move slowly from fresh water into higher salinity waters, getting more and more salty as they move out, and these jetties really make that impossible,” explained David Scott, Lower Fraser research and restoration coordinator for the Raincoast Conservation Foundation.
“We’re trying opt allow them to move back into those transition areas where they can feed and grow and get ready for salt water before they move into the ocean.”
The jetty has been in place for more than a century, and was originally installed to allow the channel to be dredged so ships could access the river’s north arm.
Raincoast said the team has now observed juvenile Chinook using the passage, an immediate success it described as “rare” in a conservation project.
The group had specifically targeted Chinook, which are particularly reliant on estuary habitats for their juvenile growth period, but says other salmon have also been using the passage.
Chinook are also the key food source for the endangered southern resident killer whales, and of the salmon species’ own populations are also listed as at risk.
According to the Fisheries and Oceans Canada, at least 50 Pacific salmon populations are currently under consideration for listing under the Species at Risk Act or by the Committee on the Status of Endangered Wildlife in Canada.
The Raincoast Conservation Foundation says more than 80 per cent of tidal habitats that young salmon of multiple species rely on in the Lower Fraser River estuary has been lost or rendered inaccessible to the fish.
“Now it’s up to us to come back and rethink these structures and think about how we can improve them for fish passage, without taking away from those human uses in the main channel,” Scott said.
“If we make just a few simple openings in them we can start to allow fish to do what they would naturally”
Planning for modification to jetties on the Fraser River began in 2017, when the foundation was approached by Fisheries and Oceans Canada, Scott said.
In 2019, the Foundation created three similar breaches in the Steveston Jetty on the Fraser River’s South Arm, where it says its it has observed high numbers of juvenile salmon gaining access to the Sturgeon Bank marsh, instead of being swept out to sea.
The project was led by the Raincoast Conservation Foundation, with support from the Pacific Salmon Foundation, Ducks Unlimited, the Tsawwassen First Nation and Lower Fraser Fisheries Alliance.