Presentation Abstract
Smolt-to adult survival rates for Puget Sound steelhead populations have declined substantially over the last 25 years and remain at or near historic lows. From 2006-2009, nearly 1,400 steelhead smolts from 9 watersheds within Puget Sound were tracked from river mouth to the Pacific Ocean using acoustic telemetry to: (1) estimate early marine survival through Puget Sound, (2) identify common areas of abnormally high mortality along the migration route, and (3) to identify factors that may influence survival. Cormac-Jolly-Seber mark-recapture models were used to jointly estimate survival and detection rate at telemetry arrays. Estimated survival rates from river mouths to near the Pacific Ocean ranged from 1.5% (Skokomish River hatchery smolts in 2009) to 34.0% (Big Beef Creek wild smolts in 2006), and averaged 14.9% for all populations. Factors influencing survival included population, migration segment, migration year, and rearing type (i.e., hatchery or wild), while geographic region, body length, and tag type (i.e., 7mm or 9mm) showed lesser effects. Comparison of survival rates between migration segments implicated central Puget Sound and Admiralty Inlet as potential areas of heightened mortality. Early marine survival rates estimated here are very low considering that steelhead smolts spend only about two to three weeks in Puget Sound before entering the Pacific Ocean. Mortality in Puget Sound may be a major driver behind low observed smolt-to adult survival rates. This study addresses a major gap in steelhead marine life history knowledge and can help to inform future Puget Sound steelhead recovery planning efforts.
Session Title
Session S-06D: Marine Survival of Salmon and Steelhead: the Salish Sea Marine Survival Project
Conference Track
Species and Food Webs
Conference Name
Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)
Document Type
Event
Start Date
1-5-2014 1:30 PM
End Date
1-5-2014 3:00 PM
Location
Room 611-612
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Steelhead (Fish)--Mortality--Washington (State)--Puget Sound
Geographic Coverage
Salish Sea (B.C. and Wash.); Puget Sound (Wash.)
Rights
This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.
Type
Text
Language
English
Format
application/pdf
Included in
Early marine survival of steelhead smolts in Puget Sound
Room 611-612
Smolt-to adult survival rates for Puget Sound steelhead populations have declined substantially over the last 25 years and remain at or near historic lows. From 2006-2009, nearly 1,400 steelhead smolts from 9 watersheds within Puget Sound were tracked from river mouth to the Pacific Ocean using acoustic telemetry to: (1) estimate early marine survival through Puget Sound, (2) identify common areas of abnormally high mortality along the migration route, and (3) to identify factors that may influence survival. Cormac-Jolly-Seber mark-recapture models were used to jointly estimate survival and detection rate at telemetry arrays. Estimated survival rates from river mouths to near the Pacific Ocean ranged from 1.5% (Skokomish River hatchery smolts in 2009) to 34.0% (Big Beef Creek wild smolts in 2006), and averaged 14.9% for all populations. Factors influencing survival included population, migration segment, migration year, and rearing type (i.e., hatchery or wild), while geographic region, body length, and tag type (i.e., 7mm or 9mm) showed lesser effects. Comparison of survival rates between migration segments implicated central Puget Sound and Admiralty Inlet as potential areas of heightened mortality. Early marine survival rates estimated here are very low considering that steelhead smolts spend only about two to three weeks in Puget Sound before entering the Pacific Ocean. Mortality in Puget Sound may be a major driver behind low observed smolt-to adult survival rates. This study addresses a major gap in steelhead marine life history knowledge and can help to inform future Puget Sound steelhead recovery planning efforts.
