Marine Habitat Use by Anadromous Bull Trout from the Skagit River, Washington

Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science
By: , and 

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Abstract

Acoustic telemetry was used to describe fish positions and marine habitat use by tagged bull trout Salvelinus confluentus from the Skagit River, Washington. In March and April 2006, 20 fish were captured and tagged in the lower Skagit River, while 15 fish from the Swinomish Channel were tagged during May and June. Sixteen fish tagged in 2004 and 2005 were also detected during the study. Fish entered Skagit Bay from March to May and returned to the river from May to August. The saltwater residency for the 13 fish detected during the out-migration and return migration ranged from 36 to 133 d (mean ± SD, 75 ± 22 d). Most bull trout were detected less than 14 km (8.5 ± 4.4 km) from the Skagit River, and several bay residents used the Swinomish Channel while migrating. The bull trout detected in the bay were associated with the shoreline (distance from shore, 0.32 ± 0.27 km) and occupied shallow-water habitats (mean water column depth, <4.0 m). The modified-minimum convex polygons (MMCPs) used to describe the habitats used by 14 bay fish showed that most areas were less than 1,000 ha. The mean length of the shoreline bordering the MMCPs was 2.8 km (range, 0.01–5.7 km) for bay fish and 0.6 km for 2 channel residents. Coastal deposits, low banks, and sediment bluffs were common shoreline classes found within the MMCPs of bay fish, while modified shoreline classes usually included concrete bulkheads and riprap. Mixed fines, mixed coarse sediments, and sand were common substrate classes found within MMCPs; green algae and eelgrass (Zostera sp.) vegetation classes made up more than 70% of the area used by bull trout. Our results will help managers identify specific nearshore areas that may require further protection to sustain the unique anadromous life history of bull trout.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Marine Habitat Use by Anadromous Bull Trout from the Skagit River, Washington
Series title Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science
DOI 10.1080/19425120.2011.640893
Volume 3
Issue 1
Year Published 2011
Language English
Publisher Taylor & Francis
Publisher location London, UK
Contributing office(s) Western Fisheries Research Center
Description 17 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science
First page 394
Last page 410
Country United States
State Washington
Other Geospatial Skagit Bay;Skagit River;Swinomish Channel
Additional Online Files (Y/N) N
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