Validation of reflex indicators for measuring vitality and predicting the delayed mortality of wild coho salmon bycatch released from fishing gears
1. Effective management of fish and wildlife populations benefits from an understanding of the effects of stressors on individual physiology. While physiological knowledge can provide a mechanistic understanding of organismal responses, its applied utility is limited because it cannot easily be used by stakeholders.
2. Reflex action mortality predictors (RAMP) is a method that involves checking for the presence or absence of natural animal reflexes to generate a condition (RAMP) score in response to stressors and to predict fate. The method has previously been validated with fishes in artificial laboratory‐ and field‐based holding studies as a responsive measure of fisheries capture stress and a predictor of delayed mortality, but has not been evaluated in the wild.
3. We used radio telemetry to monitor migration success of 50 endangered coho salmon Oncorhynchus kisutch following incidental capture in an aboriginal beach seine fishery in the lower Fraser River (Canada). RAMP was used to measure the condition of fish at release and to predict migration success following capture. Biopsy of an additional 43 coho profiled physiological condition at time of release.
4. Individuals with greater reflex impairment (higher RAMP scores) at release experienced significantly higher rates of migration failure. RAMP scores were also significantly correlated with fishery handling time. Plasma variables showed that captured coho had experienced physiological stress characteristic of exhaustive exercise and hypoxia, with significantly elevated cortisol and lactate values for fish entangled longer in fishing gear.
5. Synthesis and applications. This is the first validation of RAMP in a wild setting. Based on our findings, fishers could use the method and make adjustments in fishing behaviour in real‐time to improve fish condition and reduce the mortality of bycatch, and conservation practitioners could monitor animal condition and identify problems that deserve management attention. RAMP is an easy, rapid and inexpensive approach to predicting mortality and measuring vitality and performed better than traditional physiological tools that cannot easily be used by stakeholders.
Document Type: Research Article
Affiliations: 1: Fish Ecology and Conservation Physiology Laboratory, Ottawa-Carleton Institute of Biology and Institute of Environmental Science, Carleton University, 1125 Colonel By Dr., Ottawa, ON, K1S 5B6, Canada 2: Pacific Salmon Ecology and Conservation Laboratory, Centre for Applied Conservation Research and Department of Forest Sciences, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada 3: Fisheries and Oceans Canada, Science Branch, Pacific Region, Cooperative Resource Management Institute, School of Resource and Environmental Management, Simon Fraser University, 8888 University Dr., Burnaby, BC, V5A 1S6, Canada 4: LGL Limited, 9768 Second St., Sydney, BC, V8L 3Y8, Canada 5: Department of Biology, Carleton University, 1125 Colonel By Dr., Ottawa, ON, K1S 5B6, Canada 6: Department of Zoology, and Faculty of Land and Food Systems, University of British Columbia, Vancouver, Biological Sciences Building 3325, University Blvd., BC, V6T 1Z4, Canada 7: Private scientist, PO Box 174, South Beach, OR 97366, USA
Publication date: February 1, 2012