Details

Autor(en) / Beteiligte

• Dusek Jennings, Eva
• Hendrix, Albert

Titel

Spawn Timing of Winter-Run Chinook Salmon in the Upper Sacramento River

Ist Teil von

• San Francisco estuary and watershed science, 2020-06, Vol.18 (2), p.1

Ort / Verlag

Davis: University of California Digital Library - eScholarship

Erscheinungsjahr

2020

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• Spawn timing in anadromous Pacific salmon may be especially sensitive to environmental cues such as river temperature and flow regimes. In this study, we explored correlations between peak spawn timing and water temperature in endangered Sacramento River winter-run Chinook. In recent drought years, rising water temperatures during egg incubation have negatively impacted winter-run Chinook populations. This paper seeks to understand how winter-run spawn timing may be affected by temperatures during adult spawner staging, and how water releases from Shasta Dam might affect these dynamics. We fit a proportional odds logistic regression model to evaluate annual spawn timing as a function of average temperatures in April and May below Keswick Dam. While the start date of spawning remains relatively constant from year-to-year, there is annual variability in when the majority of spawning occurs. Cool springtime temperatures trigger winter-run Chinook to spawn earlier, whereas warm springtime temperatures trigger fish to spawn later. Prior to dam construction, winter-run Chinook spawned in cool, spring-fed streams that are now inaccessible to migrating salmonids. Temperature-driven spawn timing would have primarily ensured sufficient time for egg maturation in cool years, while secondarily preventing mortality in warm years. In the current winter-run Chinook spawning grounds, this relationship may have important applications to management of Shasta Dam water releases during conditions when thermal mortality can affect developing winter-run Chinook eggs.