Testing for delayed mortality effects in the early marine life history of Columbia River Basin yearling Chinook salmon

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 496:159-180 (2014) - DOI: https://doi.org/10.3354/meps10692 Theme Section: Tracking fitness in marine vertebrates Testing for delayed mortality effects in the early marine life history of Columbia River Basin yearling Chinook salmon Erin L. Rechisky1,*, David W. Welch1, Aswea D. Porter1, Jon E. Hess2, Shawn R. Narum2 1Kintama Research Services, Nanaimo, British Columbia V9S 3B3, Canada 2Columbia River Inter-Tribal Fish Commission, Hagerman, Idaho 83332, USA *Corresponding author: erin.rechisky@kintama.com ABSTRACT: Juvenile Snake River Chinook salmon Oncorhynchus tshawytscha pass through 8 major hydroelectric dams during their >700 km migration to the sea, or are transported downriver to avoid these dams. Both of these anthropogenic processes may decrease fitness and lead to delayed mortality in the estuary and coastal ocean, and thus reduce the rate at which adults return to spawn. Using a large-scale telemetry array, we tested whether there was support for (1) hydrosystem-induced delayed mortality (hydro-DM) of yearlings migrating from the Snake River relative to yearlings migrating from the mid-Columbia River, and (2) transportation-induced delayed mortality (transport-DM) for transported Snake River yearlings relative to yearlings which migrated in-river. We also tested for differential early marine survival between yearlings migrating from the Snake and upper Columbia Rivers. In 2010, seaward migrating yearling Chinook were captured at dam bypasses and origin was based on capture location; in 2011, dam-caught fish were identified using genetic stock identification. Survival of all groups during the initial 750 km, >1 mo long migration through the estuary and coastal ocean to northwestern Vancouver Island ranged between 14 and 19% in 2010 and was lower in 2011 (1.5-8%). We found no support for hydro-DM, as survival of in-river migrating Snake and mid-Columbia River yearlings was indistinguishable. We found mixed results for our transportation study, with no support for transport-DM in 2010, and weak support in 2011. Our study provides further evidence that freshwater management strategies may not increase the rate of Chinook salmon returning to the Snake River if prior freshwater experience has no substantial influence on subsequent survival in the ocean. KEY WORDS: Oncorhynchus tshawytscha · Latent mortality · Transportation · Snake River · Early marine survival · Acoustic telemetry Full text in pdf format Supplementary material Corrigendum PreviousNextCite this article as: Rechisky EL, Welch DW, Porter AD, Hess JE, Narum SR (2014) Testing for delayed mortality effects in the early marine life history of Columbia River Basin yearling Chinook salmon. Mar Ecol Prog Ser 496:159-180. https://doi.org/10.3354/meps10692 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 496. Online publication date: January 27, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.