Future of salmon on Seymour River at great risk due to rockslide

Dec 19 2017, 8:53 pm

More than two years after an enormous rockslide crashed into the Seymour River, little work has been done to clear the blockage in the river preventing salmon from reaching 14 kilometres of highly productive upper river habitat and spawning grounds.

The situation is now so dire that the Outdoor Recreation Council of British Columbia (ORCBC) has designated the river as one of the most endangered rivers in the province.

In December 2014, 50,000 cubic metres of falling rock – enough to fill 20 Olympic swimming pools – created a natural dam that caused water levels upstream to rise by about 10 metres. Shortly after the slide, it became clear that coho and steelhead stocks were unable to swim seaward or up the dam.

To protect the stock, conservation volunteers spent 2,500 hours last fall hand-carrying fish above the slide or into trucks that drove the fish into the river’s hatchery. 2015 was particularly a precarious year for river: A non-existent snowpack meant river water levels were low, and in turn this also meant water temperatures were abnormally high – unsuitable for salmon that prefer swimming in colder waters.

Of course, having volunteers hand-carry the fish is not sustainable nor is it anywhere as effective as a passable river stream. ORBC says a long-term solution has been agreed to by various federal and provincial government agencies, Metro Vancouver Regional District, and the District of North Vancouver. But with an estimated $1.2 million cost over five years, funding is another major obstacle for the salmon.

The plan would involve using scaling crews and low velocity explosives to reshape the rock slide – to create a 7% grade channel for fish to swim up and down. Once the rock has been split into smaller fragments, high water events that typically happen five or six times a year will be able to move some of the rock downstream through the traction process of erosion.

“Given the importance and uniqueness of the Seymour’s coho salmon and steelhead stocks in the Lower Mainland, everything possible must be done to mitigate the impacts of the slide,” said Mark Angelo, Chair of the Council. “Both the Province and the DFO should be major financial contributors and partners to the effort.”

Without taking necessary action, the group predicts that the salmon species could be reduced to remnant populations by 2019. It will have a profound on the North Shore’s ecosystem given that black bears, minks, otters, and eagles have a diet that largely depends on healthy fish stocks.

It could cause more of these wildlife species to roam further south – in North Vancouver’s neighbourhoods and other urban areas – in the search for food.

The Seymour River is just one of four runs in the entire Lower Mainland. There is an early coho run on the neighbouring Capilano River and two summer steelhead runs in the Fraser Valley.

[youtube id=”vXBh9grptCo”]

DH Vancouver StaffDH Vancouver Staff

+ News