Catch and release cutthroat trout. Photo by Don Daniels

Trout and coho stranded in pools with reduced food amid drought on North Island

Streamflows remain low despite rainfall

Despite rainy weather, ongoing drought conditions on the North Island may reduce trout and coho numbers as low streamflows leave fish stranded and higher water temperatures snuff out insects that provide them with food.

“It is fairly unusual for the North Island to be this dry,” said Jaroslaw Szczot, senior aquatic ecologist with the provincial Ministry of Forests. “I think the fires last year proved that.”

The usual wet winter didn’t happen, and current low streamflows wouldn’t normally be seen until mid-August or September, he said. There’s also a groundwater deficit from last year.

The most affected fish species are those that do their rearing in the streams and rivers, including coho salmon, steelhead and cutthroat trout. Earlier this year, spring chinook were also affected.

The Campbell River is shown on July 9, 2019. Drought conditions are affecting streamflow across the Island. Photo by David Gordon Koch/Campbell River Mirror

“(The chinook) migrate in May, so typically they’ll have enough water,” he said. “This year it was a little bit different because we didn’t have the water in May.”

For habitat, trout prefer to sit in so-called “riffles” of high-velocity water, where insects hatch. But those are the first areas to dry up during a drought, Szczot said.

Riffles also produce food flowing into pools that serve as coho habitat, he said, and “there’s nothing coming in from the riffles.”

READ MORE: Conditions ‘very dry’ in Campbell River and across Vancouver Island despite rainfall

This also means that trout have nowhere to go except pools. As the coho and trout become concentrated in the pools, they will come into competition with each other.

Higher water temperatures also mean algae blooms may increase, reducing insect production that fish depend on.

“It’s basically a cascading effect,” said the Nanaimo-based scientist, who was preparing to visit the Sayward area to monitor flows on Wednesday morning.

A screenshot from the B.C. Drought Levels Map, updated July 4, indicates very dry conditions across Vancouver Island.

All of this could mean lower numbers of trout and coho. Most streams from Campbell River to Victoria have already been affected in this way for perhaps five years due to increased drought conditions, Szczot said.

The changes will ripple throughout the ecosystem, including possible shrinkage of wetland vegetation such as cattails and impacts on water-bound species like frogs and toads.

“We haven’t heard of any bigger animals being impacted,” Szczot added. But the changes may result in more frequent cases of animals like bears wandering around human-populated areas, he said.

“I know there’s a lot reports of black bears hanging around people, so that’s a possibility, that they’re running out of that wet, shady habitat and they’re just looking for other sources to cool down.”


@davidgordonkoch
david.koch@campbellrivermirror.com

Like us on Facebook and follow us on Twitter

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

Check out a new future at career and education fair in Comox

Event today features booths from more than 40 employers and educational institutions

BC Hydro urging caution around Campbell River system as filling reservoirs require water release

BC Hydro began a system-wide extra water release Wednesday night

Campbell River artists looking for a spot to put a 20-foot long driftwood salmon

Collaboration between Eiko Jones, Kim Isles and Alex Witcombe is garnering attention

Read Islanders look to purchase, preserve 20 more acres of forest lands

Campaign has raised over $97K of $115K goal to add to the $50K already donated by local family

Residents oppose bar proposed for Campbell River neighbourhood

UPDATE: Spokesperson says the plan is for an ‘entertainment venue’ not a pub

VIDEO: Rare ‘ice circle’ spotted on Kamloops river

An ice circle or ice pan, has formed in the chilly waters just east of the Yellowhead Bridge

Uber, Lyft approved for ride-hailing in Lower Mainland

Kater Technologies Inc.’s application was rejected

B.C. man rescued after getting trapped headfirst in well as water level rose

The rescue involved crews from Oak Bay and Saanich

Investigators in wildfire-torn Australia head to site of B.C. airtanker crash

The B.C. government sends condolences to Port Alberni-owned Coulson Aviation

RCMP investigating sexual allegation against Lower Mainland police officer

Delta officer suspended while the alleged off-duty incident involving a co-worker is investigated

Former Mountie, sports coach convicted of sex abuse in B.C. granted day parole

Alan Davidson was sentenced to almost six years for abusing seven boys in the late 1970s and early 1990s

VIDEO: Person in wheelchair narrowly avoids collision with car in Kelowna

There were no injuries in the scary looking near-accident last week in Rutland

Here’s what Canada is doing to stop the coronavirus from getting in

Health officials are monitoring multiple possible cases in Canada

Most Read