Laurie Weitkamp, research fisheries biologist for NOAA’s Northwest Fisheries Science Center, briefed the Council at its October meeting on the latest survey of Pacific salmon habitats across the North Pacific Ocean.
The International Year of the Salmon is the largest international research initiative on the resilience of salmon throughout the Northern Hemisphere. Epic salmon migrations through rivers and oceans take salmon across borders and cultures, so sustaining them requires a large-scale solution.
Adding to this challenge is an increasingly extreme and uncertain climate future. By gathering more data on the ocean phase of the salmon’s life cycle, researchers hope to improve efforts to assess, forecast, and manage salmon. Knowing which parts of the ocean they're using helps predict the impact of unusual conditions like marine heat waves. A better understanding of high seas ecology should provide insight into factors affecting salmon survival in the ocean and what we can do in freshwater and estuaries to mitigate the effects of a warming climate.
Between February and April 2022, five research ships—two each from Canada and the U.S. and one from Russia–sampled 131 stations over approximately 2.5 million square kilometers in the Central and Eastern North Pacific Ocean. Their combined effort saw a catch total of 2,321 salmon and steelhead.
The expedition brought together scientists from Canada, Japan, the Republic of Korea, the Russian Federation, and the United States representing the five member countries of the North Pacific Anadromous Fish Commission.
Detailed analyses are just starting to emerge, and scientists will be analyzing and synthesizing the data for the next year. To tell a complete story of what happens to salmon in the open ocean, scientists are combining their data sets across vessels. Data mobilization is a huge piece of the 2022 expedition as scientists collaborate internationally and prepare data to be shared across research groups. “There are a lot of management questions we’re hoping to answer,” said Weitkamp.
Columbia River coho, chum, sockeye, and some Chinook use the high seas, where they co-mingle with stocks from North America and Asia. “Because the fish are mixed together, we need to focus our efforts on international cooperation,” noted Weitkamp.
Early theories that predation is a major source of mortality on the high seas has come into question since few potential predators were caught by nets or observed through environmental DNA analysis. If predation isn’t the source of mortality, then what is? “There just weren’t many predators out there,” noted Weitkamp.
Although the Council’s Fish and Wildlife Program doesn’t contribute funding to the expedition, its research will help deepen our understanding of Columbia River salmon survival as ocean conditions continue to change.