Two salmon conservation technicians slowly drag a wide net through the north arm of the Fraser River, past the entrance to a marsh that until recently was so densely packed with invasive cattails, even small juvenile salmon may have struggled to navigate it.
As they start to close the net, known as a seine, to temporarily trap any fish they may have caught, biologists Dave Scott and Daniel Stewart wade into the river to help. They use a small netted scoop to pluck out a tiny fish and deposit it into a bucket for a closer look.
The team’s already caught a pile of three-spined stickleback and a small staghorn sculpin today, but it’s the juvenile salmon that elicits a cheer.
While most young coho and sockeye salmon pass through the Fraser River estuary more quickly, for juvenile Chinook salmon these tidal marshes offer a crucial refuge where they can feed and grow for about six weeks before venturing out into the sea. But a lot of these important marshes have been degraded or lost entirely to urban and industrial development, just one of the many challenges declining B.C. salmon populations are struggling to overcome. And the difficulties faced by salmon in this particular marsh reveal that repairing those habitats is no easy solution.
As part of its restoration work at the Woods Island Marsh, the Raincoast Conservation Foundation team is monitoring fish use by netting near the outflow of the marsh. Alongside a pile of three-spined stickelback, the team caught a small sculpin in their nets one morning in July.
This marsh — known as the Woods Island Marsh — was created in the 1990s as compensation for habitat destroyed by a temporary barge off-loading facility used during construction of a runway at the Vancouver International Airport. In a statement, Alexandra Coutts, a spokesperson for Fisheries and Oceans Canada, said the proponent was released from requirements to monitor and maintain the marsh after it met its targets for effectiveness.
Today the marsh sits within the Sea Island Conservation Area managed by Environment and Climate Change Canada. But for a long time after it was deemed to be functioning effectively, there was very little management of the marsh itself, says Scott, the Lower Fraser research and restoration director with Raincoast Conservation Foundation.
Juvenile Chinook salmon will spend six weeks or so in the estuary feeding and growing before venturing out into the Pacific Ocean.
“Me and Dan aren’t of the opinion that you can build a human-constructed marsh area and then think that it’s going to turn into a natural ecosystem that needs zero management in the future,” Scott said. “It’s just not very plausible.”
The evolution of Woods Island Marsh supports their hypothesis. Invasive cattails moved in, which “really changes the whole food web dynamic,” Stewart said. Cattail can take longer to break down than some native plants, and ultimately affects the availability of food for growing salmon preparing for their journey into the vast Pacific Ocean.
Some three decades after it was first constructed, Raincoast has been working to restore the marsh and improve salmon habitat with federal funding. In March, Fisheries and Oceans Canada committed $2.6 million to support Raincoast’s salmon habitat restoration work in the Lower Fraser, including at Woods Island, over three years. The federal and provincial governments also jointly committed $5 million last year for Ducks Unlimited Canada’s habitat restoration efforts, which includes restoration of old offset projects, Coutts said.
Invasive cattails are still thriving in a marsh connected to Woods Island Marsh, so the Raincoast Conservation Foundation team will continue to monitor it and remove any invasive plants that move in.
Much of the restoration work at the Woods Island Marsh was done earlier this year. Piles of sediment were dug out to improve water flow and thousands of seedlings, mostly Lyngbye’s sedge, were re-planted after their cattail competitors were cut back.
At low tide, the tall tufts of grass-like sedge offer splashes of green against the mucky marsh bottom. In just a few years each ebbing tide will reveal a lush meadow of prime rearing habitat.
“Sedge is this highly productive plant that breaks down and is an important part of the detrital food web of this estuary,” Stewart said. The bits of broken-down sedge are food for invertebrates which are in turn eaten by juvenile salmon, like the one swimming in the researchers’ bucket.
Ongoing maintenance needed to ensure offset projects offer good salmon habitat
The newly restored area will require ongoing monitoring and maintenance in the years ahead.
So the two biologists and their team will continue to cut back any invasive cattails and check in on how juvenile salmon use the restored area. (Though Stewart did note non-governmental organizations sometimes struggle to get long-term support for monitoring and maintenance from funders who would rather support new restoration efforts.)
It’s this ongoing attention they’d like to see paid to all offset projects in the estuary. For decades, companies have been expected to invest in habitat compensation sites to offset the impacts of industrial projects. More than 100 tidal marshes have been created in the Fraser River estuary since the 1980s, according to a study by Stewart and his co-authors, which was published in the journal Wetlands last year. But they found that sites have a limited chance of success if they are ultimately ignored, even after some initial years of monitoring.
“We’ve sometimes been a little bit overconfident in how they’re functioning,” Stewart said. “In some cases, it kind of feels like we’re flying in the dark.”
Restoration work earlier this year at the Woods Island Marsh involved removing the invasive cattails as well as piles of sediment to improve water flow. Photo: Alex Harris / Raincoast Conservation Foundation
The marsh was replanted with native species like Lyngbye’s sedge, Baltic rush, soft-stemmed bulrush and wapato.
Alongside issues with invasive plants, their review of 78 constructed marshes found half had lost vegetated area since they were first built, leaving mudflat where there was once marsh. While further study is needed to better understand the cause of those losses, the researchers suggest grazing by Canada geese and erosion from boat wakes could be partially responsible. Overall, about nine per cent of the marsh area in their study had died back, undermining the goal that these projects would help offset habitat destruction from industrial projects.
“There is something broken about the way we manage these ecosystems,” Stewart said. “A lot of sites are in disrepair, are completely invaded by invasive species and are really in need of ongoing maintenance.”
Scott said it might be difficult to require project proponents to return to their offset projects every 10 years or so for maintenance — “that just isn’t really going to fly in development,” he warns — but he does see a role for the federal government in long-term management.
While Raincoast and its partners were able to secure federal funding to support restoration of the Woods Island Marsh, there’s still no consistent long-term management plan for legacy offset projects to ensure they continue to meet their goals.
As it stands, projects authorized under the Fisheries Act are required to monitor offsetting projects for five-to-10 years or more, depending on the results, to ensure they’re functioning as intended, Coutts said. Once they’ve met their effectiveness targets the proponent is released from its responsibilities and the site has the same federal protections as all other fisheries habitats, Coutts explained in the statement.
More industrial pressures in Fraser River add urgency
In the Fraser River estuary, an area that’s already lost the majority of its floodplain habitat and where major new industrial projects are still being built, the lack of long-term management planning is an especially pressing concern.
It’s one of the reasons Stewart opposed the Roberts Bank Terminal 2 project, which will destroy about 177 hectares of habitat in the Fraser River estuary. The Port of Vancouver says it is creating and restoring 102 hectares of habitat for species like Chinook and Dungeness crab, including tidal marshes. But Stewart isn’t convinced this will adequately offset the harms the project creates in the long-term.
Biologists Dave Scott and Daniel Stewart say there should be better long-term management of offset projects to help ensure they meet their goals of improving salmon habitat.
“Based on the mixed outcomes of habitat compensation and offset projects in the estuary to date, including recent projects, I am concerned that the resources required to effectively manage and maintain these projects over the long-term may be underestimated. Also, insufficient accountability may exist to ensure their functioning in the long-term,” he said in an email to The Narwhal.
Going forward, Stewart said he sees a need for a fund that companies contribute to, which could support long-term monitoring and maintenance of offset sites by First Nations or non-governmental organizations.
As part of his doctoral studies at the University of British Columbia, he’s also comparing the insect and fish populations that use constructed marshes relative to natural marsh areas. This kind of research is important, he said. “The more we can learn about these sites, the more opportunity we have to do things better going forward.”
