Fishery expert says he is optimistic about long-term prospects for Bristol Bay sockeye salmon
The long-term outlook is bright for Bristol Bay sockeye runs, source of a thriving commercial fishery that has enjoyed record-breaking returns and harvests in recent years, a salmon expert told a conference last week.
Part of the credit goes to the warming climate in that southeast Bering Sea region, Daniel Schindler, a professor at the University of Washington’s School of Aquatic and Fishery Sciences, said in a teleconferenced presentation on Friday to the two-day Bristol Bay Sustainability Summit held in Dillingham.
“Unlike most stories about climate change that we hear across the world, Bristol Bay has actually benefited from climate warming so far,” said Schindler, a Bristol Bay expert who helps lead the university’s Alaska Salmon Program. Lakes and rivers are warming up, and the warming in the nearshore ocean has enhanced survival of juvenile salmon, he said in his conference presentation.
That presents some big questions, he said: “Should we continue to expect more fish to return to Bristol Bay, and how much more warming can these ecosystems and this fish accumulate before they start declining, like they have in the Lower 48 and in the southern parts of the range of the salmon?”
The answer is that Bristol Bay, which is already the site of the world’s biggest sockeye runs, will likely keep producing lots of sockeye, he said. “Bristol Bay watersheds probably still have a lot of potential warming that will increase salmon productivity that we should expect to see in the next few decades,” he said.
But Bristol Bay’s positive salmon outlook is conditioned on continued careful management of harvests and continued protection of habitat, Schindler said.
The Bristol Bay region has several advantages over others that produce salmon, Schindler said. The rivers are short, with individual characteristics that contain a wide degree of ecological diversity. In some places, fish do better in warm conditions and in others, they thrive in cool conditions; the wide ecosystem diversity allows returning sockeye salmon to pick their spots to swim and adjust and thrive as climate conditions change, he said.
The more that habitat is protected across the wide diversity of river and lake ecosystems, the more opportunities that salmon have to adjust to changing conditions, he said.
Given all the characteristics of the Bristol Bay watershed, including lakes used by sockeye that have become more productive as temperatures warm, “I’m quite optimistic that there’s at least 100, maybe 200 years of warming left in the Bristol Bay systems before we have a lot of problems with migrating fish,” Schindler told the conference audience.
That is a contrast to long, big rivers like the Yukon and Kuskokwim in Alaska, which have suffered recent salmon crashes, or the Fraser or Columbia south of Alaska, he said. “Those fish are already suffering from warm temperatures. I would argue that things do not look particularly promising for rivers like the Yukon,” he said.
The bright outlook for Bristol Bay sockeye contrasts with the picture for Chinook salmon in that region and others, Schindler said in an interview on Tuesday.
“Chinook are down everywhere, from Sacramento up to the Yukon,” he said. That includes Bristol Bay, where Chinook runs have diminished over the years.
The reason or reasons remain unclear, he said. There are theories about climate change in the ocean or in the rivers, though there are mixed signals from the various ecosystems, he said. He doubts that Chinook harvest management or bycatch by Bering Sea trawlers is to blame, he said.
“It could be related to the changes in the body size, but it’s not clear that’s the case either,” he said, referring to studies about shrinking salmon sizes among multiple Alaska species and his own work with University of Washington colleagues documenting the shrinking size of Chinook salmon.