Fisheries scientists have estimated for the first time that 54.5 million Pacific salmon are living in the Gulf of Alaska — providing a valuable new tool to predict how many fish will be returning to B.C. streams to spawn this fall.
This new comprehensive count is critical for First Nations, commercial and recreational fishermen, coastal communities, businesses relying on the wild fishery, and fisheries managers trying to figure out why some stocks have declined drastically in certain years or crashed altogether.
Data were gathered in a month-long privately organized Gulf of Alaska survey using a chartered Russian trawler to haul in salmon for analysis. Other surveys have been carried out in the past, but this February-March expedition was the first to carry scientists from all five Pacific salmon-producing countries to collect and share data.
Salmon stocks that have or continue to face drops in recent years include sockeye returning to the Fraser and Adams rivers and several chinook populations that are in dire straits. Chinook are the favoured food of the endangered southern resident killer whales, today numbering only 74.
Nanaimo resident and fourth-generation fisherman Jordan Belveal said: “Getting a good picture of ocean-survival rates would definitely, I think, create a more accurate estimate of how many fish are going to be coming back.” While forecasters can be fairly accurate, they have been surprised with higher or lower than expected returns, he said.
Salmon used to be the backbone of B.C.’s fishing industry. But dwindling numbers through past decades forced the commercial sector to downsize and adapt.
“You can’t really rely on salmon to make a living in fishing anymore,” said Belveal, captain of the Foremost.
He fishes for mainly U.S.-bound chinook and coho off Haida Gwaii, but also goes after rockfish, ling cod, halibut and tuna.
Vladimir Radchenko, a chief scientist on the survey who headed up the work calculating salmon numbers in the Gulf, estimates 54.5 million Pacific salmon are in the area of the gulf that was surveyed.
Within that figure, he estimates there are:
• chum: 27.73 million
• coho: 13.59 million
• sockeye: 9.04 million
• pink: 4.21 million
• chinook: 0.37 million
He believes that numbers of pink salmon and chinook salmon are largely underestimated because pinks are likely in a more southerly area than was surveyed, while chinook live in deeper waters.
Radchenko is executive director of the Vancouver-based North Pacific Anadromous Fish Commission, an intergovernmental agency, which backed the expedition as a key project for the International Year of the Salmon.
Estimates among the five species already point to the need for a followup survey with more resources, said fisheries scientist Richard Beamish, who organized the expedition. Beamish and Brian Riddell, retiring executive director of the non-profit Pacific Salmon Foundation, raised almost $1.5 million. The Pacific Salmon Foundation, the U.S.-Canada Pacific Salmon Commission, the federal and B.C. governments and the B.C. Salmon Farmers Association are among donors.
Salmon spend the vast majority of their lives in the ocean, and little is known about their time out there. Funds raised paid to charter the Russian trawler, Professor Kaganovsky, with its crew, and to bring along 21 scientists from Canada, Russia, the U.S., Japan and Korea.
Returns from salmon living in the gulf have been highly variable, the fish commission said. It’s hoped that the survey results will help explain what is happening in the ocean at a time of climate change, as sea life faces a quickly changing environment.
The aim of the project is to understand the mechanisms affecting salmon survival in the gulf, particularly in their first winter at sea, and to use that information to provide the best stewardship possible, Beamish said.
Scientists analyzed DNA to pinpoint the home streams of salmon found in the gulf. They examined the condition of the fish, available prey, where the fish are within the gulf, water temperature, salinity, pollution and more. They collected samples to take to their own laboratories.
Beamish said the abundance estimate could provide early notice of salmon returns.
“Now, the question is: How reliable is that estimate? And we won’t know that until the fish start coming back this fall.”
Already, the survey “indicates that estimating the abundances of salmon is possible,” he said.
Scientists saw lower than expected numbers of pink salmon and higher numbers of coho. Now they are waiting to see if returns will be lower than predicted for pinks and higher for coho.
“Pink salmon should have been the most abundant and they should have been more abundant than chum salmon,” Beamish said.
This is an odd-numbered year, and returns of pink salmon in odd-numbered years are always larger collectively than in even-numbered years, he said. “In the Fraser River, virtually all pink salmon come back in odd-numbered years.”
Because the abundance was so much lower than expected, there is a possibility that pink returns from the Fraser River north to southeast Alaska will be below what people expected, Beamish said.
“If that turns out to be true, then what we saw in this expedition was an advance warning of that happening.”
This sort of information is new to the West Coast and has never been available before, he said.
If pinks return at normal numbers — not lower, as the survey indicated — “then the interpretation is that our survey only surveyed the northern distribution of pink salmon,” Beamish said. That possibility is in line with Radchenko’s supposition.
“What it tells us is that when you are going to do this again, you really have to have two ships out there and you really have to survey a larger area,” Beamish said.
Another surprise is that coho numbers were “quite spectacular,” he said. Scientists had thought that species would be living close to shore. They were “far more abundant than we expected.”
Most of those coho will be returning to their streams this year. Based on the survey numbers, it is reasonable to expect coho returns from California through to southeast Alaska to be better than expected, he said.
Chinook numbers are “very low” and that was anticipated, he said.
But chinook salmon are always less abundant, based on other information collected previously, such as catch rates, he said.
Another factor is that chinook tend to live deeper in the water column, below the trawl net’s depth of about 50 metres, something that Radchenko noted, as well.
Chinook are bigger and faster than other salmon, making them more difficult to catch, Beamish said. Scientists take that into account when calculating fish numbers.
Beamish launched this endeavour because of the success Russia has had in predicting salmon returns off its east coast for the past 20 years.
“There is the reliability because we are using the same methods, the same ship, the same crew and the same calculations that have proven to be reliable off the east coast of Russia.”
Usually, the Russians send two or three ships surveying a larger area and are thus able to return with a reliable estimate, he said.
Russia has the experience to make estimates that are essentially validated the next year when the fish return, Beamish said.
“We are duplicating the same thing for the first time, and our estimates now need to be calibrated with what comes back and, of course, we need to do this again.”
- Carla Wilson, Times Colonist