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

Charges dropped against officer who shot and killed Hudson Brooks in South Surrey

‘I feel like I’ve lost Hudson all over again,’ says mom

Here’s why you may not have seen many federal election signs in Surrey

Earlier this year, Surrey council banned election signs on public property, highways

‘Men of Curling’ calendar features Surrey’s Tardi, who went rock climbing with a curling rock

Tyler Tardi, 21, now curls on men’s circuit, meaning he won’t play at 2020 nationals in Langley

‘Jail’ time for Surrey business and community leaders in Crime Stoppers fundraiser

Metro Vancouver organization to host Jail & Bail event Friday at Central City’s outdoor plaza

‘I shouldn’t have done it,’ Trudeau says of brownface photo

Trudeau says he also wore makeup while performing a version of a Harry Belafonte song

‘We still did not get answers’: Vancouver parents demand expulsion after students’ racist video

‘We were unable to get confirmation from the VSB, but he hasn’t returned as of yet,’ says Marie Tate

B.C. ‘tent city’ disputes spark call for local government autonomy

UBCM backs Maple Ridge after province overrules city

B.C. drug dealers arrested after traffic stop near Banff turns into helicopter pursuit

Antonio Nolasco-Padia, 23, and Dina Anthony, 55, both well-known to Chilliwack law enforcement

‘What goes up will come down’: Gas prices spike in Metro Vancouver

Petroleum analyst Dan McTeague says prices will fall Thursday

B.C. MLA calls on province to restrict vaping as first related illness appears in Canada

Todd Stone, Liberal MLA for Kamloops-South Thompson, introduced an anti-vaping bill in April

Chilliwack woman wins right to medically assisted death after three-year court battle

Julia Lamb has been the lead plaintiff in a legal battle to ease restrictions on Canada’s assisted dying laws

B.C. bus crash survivor petitions feds to fix road where classmates died

UVic student’s petition well over halfway to 5k signature goal

Most Read