Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8832
Title: Development of underwater recorders to quantify predation of juvenile Chinook salmon (Oncorhynchus tshawytscha) in a river environment
Author: Nicholas J. Demetras, David D. Huff, Cyril J. Michel, Joseph M. Smith, George R. Cutter, Sean A. Hayes, Steven T. Lindley
Publication Year: 2016
Journal: Fishery Bulletin
Volume: 114
Issue: 2
Pages: 179-185
DOI: 10.7755/FB.114.2.5
Keywords: predation,salmon,rivers
Abstract:

Recent acoustic tagging of juvenile Chinook salmon (Oncorhynchus tshawytscha) in the southern portion of California’s Sacramento–San Joaquin Delta has revealed extremely low survival rates (<1%), possibly due to predation by piscivorous fishes. We evaluated predation as a cause of low survival by designing and testing freely floating GPS enabled predation-event recorders (PERs) baited with juvenile Chinook salmon. We estimated predation rates and identified predation locations within a 1-kilometer reach of the Lower San Joaquin River. We modeled the relationship between time to predation and environmental variables with a Cox proportional hazards analysis that accounts for censored data. Our results indicated that an increase of 1 m/s in water velocity elevated the minute-by-minute hazard of predation by a factor of 9.6. Similarly, each increase in median depth decreased the predation hazard by a factor of 0.5. The mean relative predation rate in the study area was 15.3% over 9 sampling events between March and May 2014. Waterproof video cameras attached to a subset (48 of 216) of PERs successfully identified predator species 25% of the time. Our GPS-enabled PERs proved to be an inexpensive and reliable tool, which quantified predation, identified predation locations, and provided complementary information for acoustic telemetry and predator diet studies.

Description:

Journal article describing the development and use of predation event recorders to quantify predation upon outmigrating juvenile salmon.

Full Text URL: http://fishbull.noaa.gov/1142/demetras.pdf
Theme: Ecosystem approach to improve management of marine resources
Foci: Characterize ecological interactions (e.g. predation, competition, parasitism, disease, etc.) within and among species.
Official Citation:

Demetras, N. J., D. D. Huff, C. J. Michel, J. M. Smith, G. R. Cutter, S. A. Hayes, and S. T. Lindley. 2016. Development of underwater recorders to quantify predation of juvenile Chinook salmon (Oncorhynchus tshawytscha) in a river environment. Fishery Bulletin 114:179-185.