Puget Sound steelhead marine survival research

Puget Sound Steelhead Marine Survival Workgroup: Erik Neatherlin, Steve Jeffries, Neala Kendall, Sandie O’Neil, Scott Pearson, Ken Warheit (Washington Department of Fish and Wildlife); Barry Berejikian, Megan Moore (NOAA Northwest Fisheries Science Center); Martin Chen (Northwest Indian Fisheries Commission); Paul Hershberger (US Geological Survey); Chris Ellings (Nisqually Indian Tribe); Mike Crewson (Tulalip Tribes); Ed Connor (Seattle City Light)

In 2013, the Washington Department of Fish and Wildlife (WDFW) and Puget Sound Partnership implemented an effort to determine where and why steelhead are dying in Puget Sound. $788,000 was appropriated to the Partnership by the State of Washington (2013-2015 biennium) for the initial phase of research. This appropriation was matched dollar-for-dollar by the project partners, for an overall investment of $1.6 million.

WDFW, NOAA, US Geological Survey, Northwest Indian Fisheries Commission, the Nisqually Indian Tribe, Muckleshoot Tribe, Tulalip Tribes, Skagit River System Cooperative, University of Washington, Seattle City Light, and the Pacific Northwest Salmon Center collaborated to develop and implement the research. The effort is coordinated by Long Live the Kings, the Puget Sound research coordinator for the overarching Salish Sea Marine Survival Project.

Hypotheses for low steelhead early marine survival predominantly focus on top-down effects. Data suggest juvenile steelhead experience rapid and high mortality in Puget Sound. Steelhead quickly migrate through Puget Sound, from river mouths to the open ocean–often in less than two weeks. Within this period approximately 80% die.

Ten studies were implemented in the first phase of research (2013-2015) to hone in on the causes of mortality. Initial results indicate that: a) the causes of mortality primarily originate in river estuaries and the marine environment through Admiralty Inlet, and b) predation and disease are the most likely culprits. However, the extent of mortality derived from each source, how these factors interact, and whether there are underlying genetic and environmental changes that may be exacerbating the impact of predation and disease must be understood. See the Research Work Plan: Marine Survival of Puget Sound Steelhead (2013-2015), Puget Sound Steelhead Marine Survival: 2013-2015 research findings summary, and affiliated publications on this site’s Resources page for details.

The Washington State Legislature provided an additional $800k in research funding in 2015-17 biennial budget to continue this work. Research efforts began in Spring 2016 and focused on:

1. tagging and tracking steelhead and seals and analyzing seal diets to further assess predation by seals
2. performing experiments to investigate the extent to which the parasite Nanophyetus salmincola contributes to mortality
3. analyzing the steelhead genome to determine whether steelhead are predisposed to mortality via disease or predation
4. assessing the role of broader changes to the Puget Sound ecosystem that may be exacerbating steelhead mortality

Results of these studies will be used to draft short-term solutions and long-term management actions that address steelhead early marine mortality and support the recovery ESA-listed Puget Sound steelhead. See the Puget Sound Steelhead Marine Survival 2015-2017 Research Plan for details on the next phase of research.

The opportunity now is to continue to leverage and build upon the research results, the critical mass of in-kind support, and the region-wide infrastructure and expertise that have been amassed as part of this project.

Operating as a component of the Salish Sea Marine Survival Project, the steelhead research is well-integrated with the efforts targeting factors affecting Chinook and coho survival.