Presentation Abstract

Puget Sound Chinook are listed as threatened under the U.S. Endangered Species Act, and efforts to recover these populations are underway. Effective planning and implementation of conservation measures designed to promote recovery require knowledge of freshwater processes governing smolt production and juvenile rearing strategies. The Washington Department of Fish and Wildlife monitors these viability parameters through a network of smolt trapping sites throughout Puget Sound including the Nisqually River, Green River, Cedar River, Skagit River and Dungeness River. At these locations, we routinely observe two distinct pulses of subyearling migration: an early movement of small fry (< 45 mm) captured immediately following emergence, and a later migration of larger parr (> 45 mm) that rear and grow in freshwater for a variable period of time. Yearling Chinook are occasionally observed, but only at extremely low catches, and only in basins with cold, snow or glacial dominated headwaters. In terms of productivity, Ricker stock-recruit analysis provides evidence for density-dependence of parr but not fry abundance. This suggests limitation in the availability of rearing habitat for parr, and we hypothesize that fry migrants move downstream because they are unable to acquire rearing territories in habitats saturated with conspecifics. In watersheds where this result is observed, habitat restoration efforts that augment parr rearing habitat would have the greatest opportunity to benefit Chinook salmon productivity. We also find evidence for strong effects of stream flow on Chinook productivity, often as a negative relationship between peak flow and survival. Finally, our smolt trapping estimates permit analysis of smolt to adult return rates, which will also be presented.

Session Title

Session S-08D: Salmon Recovery: Implementation and Progress I

Conference Track

Species and Food Webs

Conference Name

Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)

Document Type

Event

Start Date

2-5-2014 8:30 AM

End Date

2-5-2014 10:00 AM

Location

Room 611-612

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

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

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May 2nd, 8:30 AM May 2nd, 10:00 AM

Life-history diversity and productivity of Puget Sound Chinook salmon

Room 611-612

Puget Sound Chinook are listed as threatened under the U.S. Endangered Species Act, and efforts to recover these populations are underway. Effective planning and implementation of conservation measures designed to promote recovery require knowledge of freshwater processes governing smolt production and juvenile rearing strategies. The Washington Department of Fish and Wildlife monitors these viability parameters through a network of smolt trapping sites throughout Puget Sound including the Nisqually River, Green River, Cedar River, Skagit River and Dungeness River. At these locations, we routinely observe two distinct pulses of subyearling migration: an early movement of small fry (< 45 mm) captured immediately following emergence, and a later migration of larger parr (> 45 mm) that rear and grow in freshwater for a variable period of time. Yearling Chinook are occasionally observed, but only at extremely low catches, and only in basins with cold, snow or glacial dominated headwaters. In terms of productivity, Ricker stock-recruit analysis provides evidence for density-dependence of parr but not fry abundance. This suggests limitation in the availability of rearing habitat for parr, and we hypothesize that fry migrants move downstream because they are unable to acquire rearing territories in habitats saturated with conspecifics. In watersheds where this result is observed, habitat restoration efforts that augment parr rearing habitat would have the greatest opportunity to benefit Chinook salmon productivity. We also find evidence for strong effects of stream flow on Chinook productivity, often as a negative relationship between peak flow and survival. Finally, our smolt trapping estimates permit analysis of smolt to adult return rates, which will also be presented.