Migration in drought: Receding streams contract the seaward migration window of endangered salmon
Abstract
Prolonged migration windows buffer migratory animal populations against uncertainty in resource availability. Understanding how intensifying droughts from climate change influence the migration window is critical for biodiversity conservation in a warming world. We explored how drought affects the seaward migration of endangered coho salmon (Oncorhynchus kisutch) near the southern extent of their range in California, USA. We tracked stream departures of juvenile coho, measuring streamflow and temperature in seven streams over 13 years, spanning a historic drought with extreme dry and warm conditions. Linear mixed effects models indicate that, over the range of observations, a decrease in seasonal streamflow (from 4.5 to 0.5 mm/day seasonal runoff) contracted the migration window by 31% (from 11 to 7 weeks). An increase from 10.2 to 12.8°C in mean seasonal water temperature hastened the migration window by three weeks. Pacific salmon have evolved to synchronize ocean arrival with productive ocean upwelling. However, earlier and shorter migration windows during drought could lead to mismatches, decreasing fitness and population stability. Our study demonstrates that drought‐induced low flows and warming threaten coho salmon in California and suggests that environmental flow protections will be needed to support the seaward migration of Pacific salmon in a changing climate.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Dec 01, 2022
- Source ID
- 10.1002/ecs2.4295
Entities
People
- Brian Kastl
- Mariska Obedzinski
- Stephanie Carlson
- Theodore E. Grantham
- William T. Boucher
Organizations
- California Department of Fish and Wildlife
- California Sea Grant
- National Geographic Society
- National Oceanic and Atmospheric Administration
- United States Army Corps of Engineers