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Achieving Productivity to Recover and Restore Columbia River Stream‐Type Chinook Salmon Relies on Increasing Smolt‐To‐Adult Survival
Author(s) -
Petrosky Charles E.,
Schaller Howard A,
Tinus Eric S.,
Copeland Timothy,
Storch Adam J.
Publication year - 2020
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1002/nafm.10449
Subject(s) - chinook wind , oncorhynchus , productivity , threatened species , endangered species , drainage basin , fishery , population , environmental science , ecology , geography , biology , fish <actinopterygii> , habitat , demography , cartography , sociology , economics , macroeconomics
We analyzed and compared productivity and survival rates of populations of stream‐type Chinook Salmon Oncorhynchus tshawytscha from the upper and middle ranges of their distribution in the Columbia River basin. These two groups of populations undergo vastly different exposures during migration through the Federal Columbia River Power System ( FCRPS ). Declines of the Snake River populations, listed as threatened under the U.S. Endangered Species Act, have been associated with the development and operation of the FCRPS . In contrast, John Day River stream‐type Chinook Salmon populations, which were less affected by the FCRPS , have declined to a lesser extent and are not listed. Smolt‐to‐adult survival rates ( SAR s) accounted for a majority of the variation in life cycle survival rates of Snake River Chinook Salmon. Productivity declined to 13% and 44% of historical productivity levels for Snake River and John Day River populations, respectively. A synthesis of previous studies contrasting anthropogenic impacts between the two regions supports the conclusion that FCRPS impacts explain the large difference in population productivity. Our results suggest that SAR s of 4% would result in an expected productivity of up to 70% of historical levels (a SAR level consistent with regional restoration objectives). The SAR s have been shown to be highly influenced by conditions within the FCRPS (e.g., water velocity and passage through dam powerhouses). Marine conditions also influence SAR s; however, meaningful management actions are only available to affect conditions within the FCRPS . Given the importance of SAR s to overall life cycle productivity, recovery and restoration strategies need to prioritize actions that have potential to substantially increase SAR s by addressing the significant impacts of main‐stem dams. This study highlights the importance of considering river management options in the face of increasingly variable and warming ocean conditions.