Fraser River pink salmon run half of prediction, after dismal sockeye returns
Salmon returns just keep getting worse on the Fraser River.
End-of-season estimates show that fewer than 3.6 million pink salmon have returned to the Fraser, less than half the median pre-season forecast of 8.7 million fish and not enough for a commercial or sport fishery.
There was a one-in-10 chance that the pink returns would be as low as 4.4 million, but the results were even worse.
“It was much less, obviously much poorer than expected,” Mike Lapointe, chief biologist with the Pacific Salmon Commission, said in an interview Thursday. The average pink run on the Fraser is closer to 12 million.
The estimated fry-to-adult survival rate of 1.6 per cent this year is half the average of 3.2 per cent.
The total catch of Fraser-bound pinks by Canada and the U.S. was just 159,000 fish this season, mainly Aboriginal fisheries but some test fisheries.
The dismal pink returns are in line with previously reported poor sockeye returns on the Fraser this season — about 1.5 million fish compared with a median pre-season forecast of 4.4 million.
Pink salmon have a two-year cycle (compared with four years for sockeye), meaning the fish that returned this year were spawned in 2015. This year’s return forecasts were based largely on counts of small fry migrating down the Fraser in 2016. The pinks travelled as far north as the Gulf of Alaska before returning to the Fraser this year as adults.
The bulk of pinks spawn downstream of the Fraser Canyon, but some have been reported as far upstream as Prince George, evidence that they may be expanding their range, Lapointe said.
He said no one really knows why ocean survival has been so poor. Food, predators, and especially ocean warming could be factors. “It’s smart to be humble and admit we don’t know,” he said. “All we know is they didn’t come back.”
Ocean conditions may have weakened fish to the point they were easy pickings for predators.
Lapointe said most ocean temperature readings are taken at the surface and may not fully reflect temperatures experienced by salmon deeper in the water. “We don’t really have the systematic sampling out there … don’t have the data to really answer the question you might want answered.”
A so-called “blob” of warm water identified in the North Pacific in the winter of 2013 and lasting into 2015 resulted in ocean temperatures in some areas of three degrees C above normal.
Fisheries and Oceans Canada said that warm ocean conditions can cause a change in species of plankton, from high-nutrition northern types to low-nutrition southern types, while increasing the presence of warmer water predators.
Warm rivers can also reduce spawning success.
Lapointe said “everyone is hopeful” that sockeye returns will be strong in 2018 — the famous Adams River cycle. About 29 million sockeye returned to the Fraser in 2010 and about 20 million in 2014, he noted.
Nate Mantua, a research scientist with the U.S. National Oceanic and Atmospheric Administration, will speak on climate change and salmon at the 13th Larkin Lecture at the University of B.C. on Nov. 14 at 5 p.m.
- LARRY PYNN
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