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NW Fishletter #392, April 1, 2019

[1] Wealth Of Data Gathered In Month-Long International Salmon Expedition

Some of the initial observations by a team of 21 scientists who sailed the North Pacific's high seas for a month to study salmon in the Gulf of Alaska concluded that pink salmon, the North Pacific Ocean's most abundant, were surprisingly scarce; that coho, which are thought to hang close to coastal areas, were found hundreds of miles offshore; and that chum were looking notably skinny.

The trip on the Russian research vessel Professor Kaganovskiy was the first winter voyage in decades to study Pacific salmon in the open ocean, and the first ever to bring together top researchers from Russia, Korea, Japan, Canada and the U.S.

Scientists believe that one-third of all Pacific salmon that originate from those five countries spend winters in the Gulf of Alaska, but have little data on their winter whereabouts.

The expedition is one of many events organized for the International Year of the Salmon, a five-year initiative to build resilience for salmon and people by sharing knowledge and raising awareness.

"I think it was successful in so many different ways," Laurie Weitkamp, the trip's chief U.S. researcher and a fisheries biologist at NOAA's Northwest Fisheries Science Center, told the Northwest Fishletter a few days after her return to land on March 18.

Weitkamp said one of the objectives--determining whether international scientists could work effectively together--was certainly accomplished. Despite language barriers and slight but significant differences in scientific methods, team members quickly figured out how to accommodate each other, she said.

One of the Russian scientists who is married to a Canadian helped translate, she said, and also noted, "You can actually do a lot with hand gestures, like thumbs up or down."

Scientifically, the team set out to discover some basic information about five species of salmon in the North Pacific, such as stock abundance, composition and the condition of Pacific salmon at the end of their first winter in the ocean.

In a very preliminary estimate made from about 400 salmon caught at 60 sampling stations, the team determined that that roughly 55 million salmon were wintering in their sampling area of about 700,000 square kilometers--or 270,271 square miles--in the middle of the Gulf of Alaska this year. The area is between 139 and 148 degrees west longitude and 47 and 53 degrees north latitude.

Weitkamp said much of the data they gathered has yet to be compiled and analyzed. But even a first glimpse of the immediate results brought some surprises.

The most notable is that coho were the second-most abundant species netted while traveling in a grid pattern some 4,800 nautical miles.

"In all of the high seas work that normally occurs during the summer, they pick up very few coho," Weitkamp said. So scientists couldn't believe that in net after net, coho kept showing up hundreds of miles offshore, she said. "Maybe they're out in the winter and then head back to the shore," she surmised. Or perhaps this winter was somehow different from most years. That will remain unknown until follow-up surveys can be done, she noted.

Weitkamp said although the information from this year's survey is expected to be extremely informative, scientists have to be careful not to draw too many conclusions until findings are repeated in subsequent years. "I've been trying to use the analogy of, if you only go to New York City on New Year's Eve, you'd get a very different impression than if you went any other time. We don't know if we were there on New Year's Eve, or another time."

Another surprise was that pink salmon comprised only 10 percent of the salmon caught, even though they're known to be by far the most abundant salmon species in the North Pacific. Pink salmon return to rivers to spawn after just one year in the ocean, and run sizes trend especially high in odd years--such as 2019.

"It was really puzzling," Weitkamp said. "They get these massive runs in odd years, so we were expecting to see a lot of pinks out there, and we didn't."

Scientists are guessing that perhaps most of the pink salmon were wintering south of their survey area, since those that were caught were mainly in the southern end, where the water was warmer.


Chum also tended to be more abundant in the southern portions of the grid, while sockeye were more abundant in the more northern locations with cooler water.

Weitkamp said it was not as surprising that they only captured three Chinook, both because they are one of the ocean's least abundant, and also because they tend to be in deeper locations. "We were fishing pretty close to the surface, so I think we were too shallow," she said.

Weitkamp said except for chum, most of the salmon they caught were in good condition, even though it was near the end of the winter. "Most of the coho and sockeye we caught looked great," she said. "They were pretty fat. But the chum were really skinny. But these are the survivors. We think from here on out, they're going to do great," she said, adding, "We were already seeing a plankton bloom as we were coming back."

The scientists won't just go by looks to determine the condition of the salmon they caught, however. Bringing back samples of each fish's spleen, heart, liver, kidney, muscle and brain, they'll conduct a variety of studies to dig down to the next level of their health, she noted.

They'll also study the tiny bones found in the ears of the fish to look at growth rates to try to determine why some salmon survive, and the vast majority die before returning home to spawn.

There is still much information to be analyzed, Weitkamp noted. In addition to catching salmon, the scientists took measurements such as temperature, salinity, and acidity at each station, and logged the many other marine creatures that were captured.

"I can't wait," she said. "I think the findings we come up with--even though it's just one time--could really shed a lot of light on what's going on in the North Pacific in winter. Everything from water temperature and chemistry to salmon," she said.

Weitkamp said in addition to scientific discoveries, highlights of the trip involved getting to see the many differences between the Russian research vessel and U.S. research ships. Weitkamp offered her observations in her own writings, describing the homey atmosphere of the Professor Kaganovskiy, with its lace curtains, living plants, and a cat who'd lived there its entire life. Drawers and counter spaces were filled with things left by previous researchers, and meals were rich with international flavor.

Best of all, she said in the interview, was the shared feeling of purpose by all those aboard, despite their differences in language and customs.

"The last two days, we put a live box on the trawl to try to catch fish that were good enough to tag and release," she said. "When we were pulling the net in, it was like 2 a.m., and I turned around and everybody that was up was watching to see what we got. This was like Haul 62 on Day 27, and people were still interested--scientists and non-scientists. And when everyone saw we got fish in the net, it was like we'd won the Superbowl."

Longtime Canadian researcher Dick Beamish led the campaign to make the voyage happen, and with Brian Riddell, executive director of the Pacific Science Foundation, raised $1.2 million from private citizens, groups and governments to charter the vessel.

Future expeditions are being planned. -K.C. Mehaffey

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Publisher/Editor-in-Chief: Mark Ohrenschall, Editor: K.C. Mehaffey
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