Warm water threatens what should be bumper year for Fraser River sockeye
This should be a big year for sockeye on Canada’s most important salmon river, but the threat of high water temperatures and several years of low fish survival is putting that forecast at risk.
Fisheries and Oceans Canada is forecasting 14 million sockeye will return to the Fraser River in 2018, which is on par with the big runs that return to the river every four years.
But, alongside that forecast, DFO warns that the fish returning in 2018 will have experienced the same “unusually warm” freshwater and ocean conditions that have coincided with low sockeye survival the past three years.
If those survival trends persist, the DFO report states the river might see as few as 5.3 million sockeye — a fraction of the forecast and a far cry from the famed red runs of the Fraser River.
River already warmer, lower
The earliest of the Fraser River’s many sockeye populations have already begun their gruelling swim upstream to spawn, and conditions are still “favourable” for the Early Stuart run, said Mike Lapointe, chief biologist of the Pacific Salmon Commission.
But fisheries managers will be watching conditions closely as the much larger sockeye runs — including the spectacular Adams River run, which can boast millions of fish — arrive later in the summer.
“The question will be, what kind of warm weather are we going to have this summer? Will we get rain, which will moderate things?” said Lapointe.
“If you get a hot spell … it could definitely warm up the Fraser quickly.”
Warmer water is trouble for salmon. It can delay their migration and accelerate disease in fish that are already “on their last legs” and “swimming probably about the equivalent of a marathon a day,” said Lapointe.
Already, the Fraser’s water level is about 20 per cent lower than average for the date, as measured Monday near Hope, B.C., likely due to early spring flooding.
Crucially, the temperature measured upstream of there was 17.7 C — more than a degree warmer than average for the date.
‘A big year in the theoretical sense’
While salmon numbers go up and down, this is a year any fish-lover should pay special attention to, because in the cycle of the Fraser sockeye it should be huge.
Most sockeye return on a four year life-cycle, and 2010 saw 28.2 million sockeye on the Fraser, the highest number in nearly a century.
That generation’s offspring, returning in 2014, were also abundant enough for a commercial fishery, but not as numerous as expected, falling near 20 million.
The median forecast of 14 million for 2018 is lower again, but a commercial opening may be possible after three “very lean” years, said Lapointe.
“If we get a good return and we’re able to have commercial fisheries this year, that would be a real bonus,” he said.
That will depend on conditions and how many fish show up in the late runs, which won’t be known until August.
“It’s a big year in the theoretical sense,” said Eric Taylor, a UBC fish ecologist and chair of the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), which has assessed the status of Fraser River sockeye.
“A small change in ocean temperature can have a huge impact,” said Taylor.
“If the conditions aren’t right in the environment … then the fish aren’t going to show up, and of course that’s happened in the past.”
Populations at risk
The backdrop to this year’s hopes and fears is an overall decline in what has been a great river for fish.
Last fall, COSEWIC found eight populations of Fraser River sockeye are in such decline that they should be legally protected under species at risk legislation.
Taylor said signs of trouble on the Fraser go beyond sockeye.
“There are lots of signals that these iconic species of salmon and sea run trout in the Fraser River are not doing well, and this has been a persistent decline since the mid-80s,” he said.
The big factors, says Taylor, are believed to be declining ocean conditions and rising river temperatures — in other words, climate change.