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Mechanisms to explain purse seine bycatch mortality of coho salmon Raby, Graham D.; Hinch, Scott G.; Patterson, David A.; Hills, Jayme A.; Thompson, Lisa A.; Cooke, Steven J.
Abstract
Research on fisheries bycatch and discards frequently involves the assessment of reflex impairment, injury, or blood physiology as means of quantifying vitality and predicting post-release mortality, but exceptionally few studies have used all three metrics concurrently. We conducted an experimental purse seine fishery for Pacific salmon in the Juan de Fuca Strait, with a focus on understanding the relationships between different sublethal indicators and whether mortality could be predicted in coho salmon (Oncorhynchus kisutch) bycatch. We monitored mortality using a ∼24-h net pen experiment (N = 118) and acoustic telemetry (N = 50), two approaches commonly used to assess bycatch mortality that have rarely been directly compared. Short-term mortality was 21% in the net pen experiment (∼24 h) and estimated at 20% for telemetry-tagged fish (∼48–96 h). Mortality was predicted by injury and reflex impairment, but only in the net pen experiment. Higher reflex impairment was mirrored by perturbations to plasma ions and lactate, supporting the notion that reflex impairment can be used as a proxy for departure from physiological homeostasis. Reflex impairment also significantly correlated with injury scores, while injury scores were significantly correlated with plasma ion concentrations. The higher time-specific mortality rate in the net pen and the fact that reflexes and injury corresponded with mortality in that experiment, but not in the telemetry-tagged fish released into the wild could be explained partly by confinement stress. While holding experiments offer the potential to provide insights into the underlying causes of mortality, chronic confinement stress can complicate the interpretation of patterns and ultimately affect mortality rates. Collectively, these results help refine our understanding of the different sublethal metrics used to assess bycatch and the mechanisms that can lead to mortality.
Item Metadata
Title |
Mechanisms to explain purse seine bycatch mortality of coho salmon
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Alternate Title |
Acoustic telemetry in fisheries management
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Creator | |
Date Issued |
2015
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Description |
Research on fisheries bycatch and discards frequently involves the assessment of
reflex impairment, injury, or blood physiology as means of quantifying vitality and predicting
post-release mortality, but exceptionally few studies have used all three metrics concurrently. We
conducted an experimental purse seine fishery for Pacific salmon in the Juan de Fuca Strait, with
a focus on understanding the relationships between different sublethal indicators and whether
mortality could be predicted in coho salmon (Oncorhynchus kisutch) bycatch. We monitored
mortality using a ∼24-h net pen experiment (N = 118) and acoustic telemetry (N = 50), two
approaches commonly used to assess bycatch mortality that have rarely been directly compared.
Short-term mortality was 21% in the net pen experiment (∼24 h) and estimated at 20% for
telemetry-tagged fish (∼48–96 h). Mortality was predicted by injury and reflex impairment, but
only in the net pen experiment. Higher reflex impairment was mirrored by perturbations to
plasma ions and lactate, supporting the notion that reflex impairment can be used as a proxy for
departure from physiological homeostasis. Reflex impairment also significantly correlated with
injury scores, while injury scores were significantly correlated with plasma ion concentrations.
The higher time-specific mortality rate in the net pen and the fact that reflexes and injury
corresponded with mortality in that experiment, but not in the telemetry-tagged fish released
into the wild could be explained partly by confinement stress. While holding experiments offer
the potential to provide insights into the underlying causes of mortality, chronic confinement
stress can complicate the interpretation of patterns and ultimately affect mortality rates.
Collectively, these results help refine our understanding of the different sublethal metrics used to
assess bycatch and the mechanisms that can lead to mortality.
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Subject | |
Genre | |
Type | |
Language |
eng
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Date Available |
2016-09-19
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0314314
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URI | |
Affiliation | |
Citation |
Raby GD, Hinch SG, Patterson DA, Hills JA, Thompson LA, Cooke SJ. Mechanisms to explain purse seine bycatch mortality of coho salmon. Ecol Appl. 2015;25(7):1757-1775.
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Publisher DOI |
10.1890/14-0798.1
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Peer Review Status |
Reviewed
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Scholarly Level |
Faculty; Graduate; Other; Unknown
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Rights URI | |
Aggregated Source Repository |
DSpace
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Item Citations and Data
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International