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.”

Like us on Facebook and follow us on Twitter

Just Posted

Welcome to Victoria, where a street can have four names

From Oak Bay to View Royal, street names change as the roadways twist and turn

Garbage piles up at Mount Doug Park in Saanich

Local resident blames the design of the garbage bins

VicPD arrest reportedly armed man wanted on Canada-wide warrant

The man was found near Centennial Square on Tuesday afternoon

Port Renfrew man charged with animal cruelty

Hot coffee poured on dog’s face, say police

Pacific FC looks for first win of the fall season in Toronto Wednesday

The Island team is currently 0-2-0 this season

VIDEO: Black bear caught climbing tree in Langford neighbourhood

Triangle Mountain residents on alert following bear sighting

Report of dead body in B.C. park actually headless sex doll

This discovery, made at Manning Park on July 10, led police to uncovering two other sex mannequins

Grand Forks fire chief found to have bullied, harassed volunteer firefighter: report

WorkSafeBC, third-party human resources investigation looking into allegations complete

Taekwondo instructor, 21, identified as B.C. bat rabies victim

Nick Major, 21, an instructor at Cascadia Martial Arts in Parksville

15-year-old with imitation gun caused ‘dynamic’ scene at Nanaimo mall

No one was harmed in Monday’s incident, say Nanaimo RCMP

B.C. on right road with tougher ride-hailing driver rules, says expert

The provincial government is holding firm that ride-hailing drivers have a Class 4 licence

RCMP investigating alleged ‘sexual misconduct’ by cyclist on BCIT campus

BCIT said they were reviewing video evidence of the incident

New home cost dips in B.C.’s large urban centres

Victoria, Kelowna, Vancouver prices decline from last year

Graphic suicide scene edited out of ‘13 Reasons Why’ finale

Suicide prevention groups support the decision

Most Read