Floods present a new survival challenge for BC salmon

As James Reinheller gazed down his flooded street in Clayburn, a neighborhood of Abbotsford, BC, on Monday, he said he saw a bizarre sight: a salmon making its way across the flooded road.

“From the bottom of the road, all the way up, he swam,” Reinheller said. “It was quite a sight to see. You just don’t expect to see salmon swimming your way.”

It’s a worrying example of a catastrophic week in the southwest province, where floods and mudslides destroyed critical infrastructure, highways and farmland — forcing tens of thousands to flee.

But the damage of what Secretary of Public Safety Mike Farnworth called a “once in a centuryStorms may be another stressor for salmon on BC’s southern coast after decades of fishing, habitat destruction and development that have sent salmon stocks into a tailspin, experts say.

Recent inclement weather such as heat domes and landslides have also stacked the odds against salmon.

Eggs could have been washed away, expert says

Salmon has evolved before to withstand flooding, but maybe not that kind, said Jonathon Moore, a biology professor at Simon Fraser University and director of the Salmon Watersheds Lab.

“Salmon is really good at finding places that don’t shed and so they evolved for flooding, but not for this level of flooding,” Moore said.

“It depends a ton on the watershed and the characteristics of the watershed.”

The biggest concern, he said, is whether newly hatched eggs could have been washed away — otherwise known as scour.

Autumn is the spawning season for many salmon species. Moore said some of the salmon species that had already hatched and built nests — or redds — for eggs before the flood may have seen those eggs washed away or covered in excess sediment or silt.

In that case, he said that maybe a generation has been lost.

“Some populations [do] not as many returning adults in the next generation. There will be fewer fry in the river in these places that have been hammered, there will be fewer young salmon the following year and then few will go to sea, fewer will come back,” Moore said.

The effects of what happened to the salmon population depend on the waterway, species and life stage of the salmon. Moore said that in the fall there are salmon at various stages of their life cycles in the freshwater system of BC’s south coast.

“This impact will not be the same for all populations and locations. There will be certain places that will be hit harder than others,” he said.

Juvenile Coho Salmon
There are different salmon species at different life stages in the river systems of the south coast of BC at any given time. Pictured above is a juvenile coho salmon. (Submitted by Jonathan Moore)

On Vancouver Island, for example, the iconic salmon run in the Goldstream River may have been hit by this weather, said Ian Bruce, the executive coordinator of the Peninsula Streams Society.

“[The run was] a third or a quarter of the recent average. So with this rain event on top of a low return, it’s very grim for Goldstream and for the friend,” Bruce said.

Younger smolts in the river would have struggled to stay put, he said.

“Sometimes they will eventually leave the creek, end up in a flood plain, and get lost,” Bruce said.

Urgent action needed

As the water subsides, the damage assessment begins. Fisheries and Oceans Canada said in a statement it will work with local community partners to assess the long-term effects on Pacific salmon.

Moore said there are things that can be done to help salmon cope with climate change, such as connecting creeks to the watershed restoration of long-buried estuaries.

On Vancouver Island, Bruce said he is working on creating rain gardens to dampen the flooding peaks and store water.

“Just as there are cumulative effects of the different stressors that salmon face, there are also the cumulative effects of the different things we can do to help and create resilient systems,” Moore said.

“Salmon has had a lot to deal with. Urgent action is needed.”

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