Sockeye salmon spawning in B.C.'s Adams River in 2010.

Ocean warming may be factor in sockeye decline

Study ties salmon productivity drop to 'shared mechanisms'

Sockeye salmon along the west coast are producing far fewer returning offspring than in the past and the SFU fishery scientists who have documented the trend say it suggests climate change may be a factor.

Randall Peterman said the study he co-authored found 24 of 37 sockeye stocks from Washington State to Alaska lost productivity since 1985, with the hardest hit runs no longer even replacing themselves.

He said the fact the decline has been widespread across both pristine and heavily disturbed watersheds points to non-local “shared mechanisms” as the more probable cause, rather than river-specific logging or pollution.

“It’s much more likely that what’s causing these changes is occurring over a large area,” said Peterman, a professor in SFU’s School of Resource and Environmental Management.

Warming oceans could be reducing the salmon food supply in the north Pacific, sending more predators towards the sockeye or increasing their vulnerability to pathogens, he said.

The culprit could also be affecting sockeye in freshwater, Peterman added.

A pathogen – either naturally occurring or spread by fish farms – could be amplified by climate changes and infecting sockeye in rivers that later die at sea.

Preliminary findings were presented in 2011 to the Cohen Inquiry, which reports in the fall with recommendations on halting the decline in Fraser River sockeye.

But Peterman said the newest analysis shows the pattern of declining productivity has spread northward to more watersheds over time.

“That trend of spreading northward is indicative of possibly climate-driven processes that become more extreme in the south first and work their way north,” he said. “The evidence is much stronger than it was.”

The theory of a fish food shortage on the high seas is backed in part because sockeye have tended to return significantly underweight in recent years. The food supply is expected to decline as the ocean warms.

But Peterman noted increased competition for the same food supply is another possibility.

The number of pink salmon feeding in the same area of the north Pacific has more than doubled, largely the result of “ranching” of pinks by Russians and Alaskans.

“Because they feed on similar food to sockeye salmon there may be increased competition,” Peterman said.

The study was published in the Canadian Journal of Fisheries and Aquatic Sciences.

Just Posted

Harrison retiree leaves legacy of ‘non-stop ideas’

Ruth Altendorf is remembered as a ‘“bubbly, enthusiastic, outgoing person’

Harrison musician Todd Richard gearing up for album release party in Chilliwack

Todd Richard’s third album, Live Your Life, features all ‘true-story’ songs

Told ‘no’ twice by local shelter, homeless Surrey man sent to Hope anyways

Deemed medically stable, patient was taxied to Hope by hospital when a spot in Surrey wasn’t located

Agassiz speed skater heading to Canada West championships

Mya Onos, 11, is qualified for her first provincials this year, and is now taking on Western Canada

Harrison considers future of memorial bench program

Harrison to keep maintaining bench plaques, council seems to feel new benches could be in the future

Harrison Hot Springs students bring ‘Twelfth Night’ to life

The adaption of Shakespeare’s classic comedy include songs and phrases from Canada’s east coast

Canucks hang on for 7-4 win over Senators

Horvat nets 2 for Vancouver

European, Canadian regulators to do own review of Boeing jet

Air Canada plans to remove the Boeing 737 Max from its schedule at least through July 1

Prime minister defends Liberal budget measures as sales effort gets underway

Conservatives under Andrew Scheer say it’s a spree funded by borrowing against the future

B.C. lottery winner being sued by co-workers

They claim he owes them $200,000 each, in a lawsuit filed in B.C. Supreme Court in Vancouver

Teacher reprimanded for conduct towards special needs student

Alan Stephen Berry told vice principal he did not have time to use positive strategies

‘Full worm super moon’ to illuminate B.C. skies on first day of spring

Spring has sprung, a moon named in honour of thawing soil marks final super moon until 2020

Having phone within sight while driving does not violate law: B.C. judge

The mere presence of a cell phone within sight of a driver is not enough for a conviction, judge says

Woman punched on the sidelines of B.C. soccer game

Both involved were watching the U21 game in West Vancouver from the sidelines when things got heated

Most Read