Premature mortality observations among Alaska’s Pacific salmon during record heat and drought in 2019

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Widespread mortality of Pacific salmon Oncorhynchus spp. returning to spawn in Alaska coincided with record-breaking air temperatures and prolonged drought in summer 2019. Extreme environmental conditions are expected to happen more frequently with rapid climate change and challenge the notion that Alaska could indefinitely provide abundant, cool freshwater habitat for Pacific salmon. A total of 110 geographically widespread opportunistic observations of premature mortality (carcasses) were collected from a variety of sources. Premature mortalities were documented for Pink Salmon Oncorhynchus gorbuscha, Sockeye Salmon O. nerka, Chum Salmon O. keta, Chinook Salmon O. tshawytscha, and Coho Salmon O. kisutch. Additionally, observations of Pink Salmon returning to spawn in Prince William Sound streams in 2019, obtained from systematic aerial surveys conducted annually, revealed low migration success in 87% of rain-driven streams (n = 30), 52% of snow-driven streams (n = 65), and only 18% of glacier-driven streams (n = 11). Salmon mortality observations were consistent with death due to heat stress resulting from high water temperatures or drought caused hypoxia and stranding. Developing a better understanding of how broad-scale climate patterns manifest at the stream scale can help us determine whether a major shift in Pacific salmon productivity is underway and inform fisheries management plans to better mitigate future risks.

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Publication type Article
Publication Subtype Journal Article
Title Premature mortality observations among Alaska’s Pacific salmon during record heat and drought in 2019
Series title Fisheries
DOI 10.1002/fsh.10705
Volume 47
Issue 4
Year Published 2022
Language English
Publisher American Fisheries Society
Contributing office(s) Alaska Science Center Water
Description 12 p.
First page 157
Last page 168
Country United States
State Alaska
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