An international scientific expedition aiming to solve the puzzle of how Pacific salmon survive in the open ocean is returning to Victoria with new questions.
After initially hauling in large catches of up to 300 salmon at a time last month, there’s been no sign of salmon in recent days.
“It is a little difficult for people to accept that scientifically, no catch is sometimes as important as large catches. I think this is the case here,” said Richard Beamish, who is organizing the $1.45-million expedition with fellow B.C. scientist Brian Riddell.
“We had relatively large catches of pink, chum and coho early in the survey and there were no salmon in the same area a few weeks later.”
It is clear that there are probably large schools of species such as coho that are moving over large areas in response to some factor, Beamish said.
The chartered trawler Pacific Legacy No. 1 left Victoria on March 11, headed up to the southern part of the Gulf of Alaska and fished off Dixon Entrance. On Friday, it was 513 miles off Cape Beale, west of Ucluelet. The team expects to return to Victoria on Tuesday.
“The low catch in the second leg was closer to British Columbia, which we will better be able to understand when we get the DNA,” Beamish said.
DNA analysis will be carried out in laboratories on shore. It allows scientists to pinpoint the home streams of salmon. Other factors affecting salmon are studied as well, including prey species and ocean conditions.
The expedition aims to help better predict subsequent salmon returns and to understand factors affecting the survival of salmon salmon through winter. The first winter at sea is seen as an indicator of future survival.
Riddell is pleased with the large sample sizes caught this year, with strong numbers for pink, chum, coho and sockeye salmon. The trip collected a good distribution of ages and body sizes.
He suggests that a greater number of vessels may be needed for such surveys. A survey planned for 2021, through the International Year of the Salmon project, might have up to five vessels out in the Pacific, he said.
Research is being spurred by decreases in the numbers of Pacific salmon returns to their home streams as climate change affects the planet. Last year was a disastrous year for many salmon stocks and for the fishermen depending on them. This year is expected to have similarily low returns.
The trawler originally carried a team of three Russians, three Americans and six Canadian researchers. The Americans left the vessel in Prince Rupert over concerns about borders closing due to the COVID-19 pandemic and the expedition continued.
The funding comes from B.C. and the federal government, the private sector, non-profit organizations and individuals.
This voyage follows a similar survey in 2019, when a team of scientists from five countries headed into the Gulf of Alaska using a Russian trawler.
“When we step back and look at the results of the two expeditions, it is clear that a major part of the life cycle of salmon remains to be discovered,” Beamish said.
Winter conditions at sea can be a challenging time to carry out a survey.
Earlier on in the cruise, the vessel faced seas of 20 to 25 feet and winds of 45 to 50 knots, said John Roach, the ship’s captain.
Aleksey Somov, of Vladivostok, one of the chief scientists on the cruise, has done similar surveys in Russian waters. He supports carrying out additional surveys to learn more about what is taking place in the Gulf of Alaska.
During last year’s survey, about 30 per of the salmon originated from B.C.’s central coast, said researcher Tristan Blaine, field technician for the Central Coast Indigenous Resource Alliance and a member of the Canadian contingent on the expedition.
While all species of salmon are important, the state of sockeye stocks are key because it is a “really treasured food fish,” he said.
Last year was the “first time some families didn’t get a chance to harvest sockeye because the numbers were so low.”
A key question is how to adapt management strategies in the wake of climate change.
“That’s been a big part of the project — looking at what changes are we seeing in the food web and how that affects salmon,” Blaine said.
Blaine’s job for the Resource Alliance sees him doing a lot of scuba diving to survey coastal rockfish populations. On this expedition, he said, “we caught several rockfish in the trawl, which is super interesting.”
Rockfish larvae were hauled up as well, he said. “I didn’t expect to see any rockfish 500 miles off shore.
“That’s a really important food for everyone.”
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