Catch Welfare in Commercial Fisheries

Breen, Mike; Anders, Neil; Humborstad, Odd-Børre; Nilsson, Jonatan; Tenningen, Maria; Vold, Aud

doi:10.1007/978-3-030-41675-1_17

Cited by 17 publications

(23 citation statements)

References 124 publications

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“…Welfare conscious fishing practices are those that minimize physical damage and allostatic load on captured animals ( Breen et al , 2020a ). Collectively, the results of this study indicate that crowding in a purse seine would likely cause increases to allostatic load, both in terms of physiological disturbance and skin injury.…”

Section: Discussionmentioning

confidence: 99%

“…Good catch welfare practices may be defined as ‘capture and handling methods that minimise the physical damage to, and allostatic load on, any retained fish until after they are either slaughtered or released, and thus promote the likelihood for post-release survival and/or good product quality’ ( Breen et al , 2020a ). In wild-capture commercial fishing, delayed mortality among unwanted and released catches is a significant challenge to the long-term sustainability of the industry ( Davis, 2002 ).…”

Section: Introductionmentioning

confidence: 99%

“…However, the primary objective of the current study was to describe the physiological and survival response of Atlantic mackerel to crowding stress (and thereby relate capture related stress to welfare outcomes) using a controlled, mesocosm-scale, experimental setup in sea-cages. A more comprehensive understanding of how mackerel physiologically respond to purse seine capture can contribute to the development of welfare conscious fishing practices that aim to promote post-release by minimizing allostatic loading ( Breen et al , 2020a ). We simulated various degrees and durations of crowding in a series of eight trials.…”

Section: Introductionmentioning

confidence: 99%

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Physiological response and survival of Atlantic mackerel exposed to simulated purse seine crowding and release

Anders

Roth

Breen

2021

Conservation Physiology

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Understanding how animals physiologically respond to capture and release from wild capture fishing is fundamental for developing practices that enhance their welfare and survival. As part of purse seine fishing for small pelagic fish in northern European waters, excess and/or unwanted catches are routinely released from the net in a process called slipping. Due to excessive crowding in the net prior to release, post-slipping mortality rates can be unacceptably high. Atlantic mackerel (Scomber scombrus) support large and economically important purse seine fisheries but are known to be particularly vulnerable to such crowding-induced mortality. Developing management advice to promote post-slipping survival for this species is currently challenging, due to a lack of understanding of how crowding influences their physiology. Here we examine the physiological response, recovery and survival of wild caught mackerel exposed to various degrees and durations of simulated crowding stress in a series of sea cage trials. The magnitude of the physiological response and its time to recovery was positively correlated with crowding density and duration and was characterized by cortisol elevation, energy mobilization and anaerobic metabolite accumulation. There were also indications of osmoregulatory disturbance. Skin injury and mortality rates showed a similar positive relationship to crowding density. The physiological disturbance was recoverable for most fish. Instead, the rate at which mortalities developed and the physiological profile of moribund fish indicated that skin injury, likely arising from abrasive contact with netting and other fish during crowding, was the probable cause of mortality. Injured fish also exhibited a loss of allometric condition relative to non-injured survivors. Crowding treatments were potentially confounded by differences in ambient oxygen reduction, water temperature and pre-treatment fish condition between trials, and densities were replicated only once. These results contribute to the development of welfare conscious fishing practices that aim to reduce post-slipping mortality.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Physiological response and survival of Atlantic mackerel exposed to simulated purse seine crowding and release

Anders

Roth

Breen

2021

Conservation Physiology

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“…Wild capture fishing can be stressful for the captured fish. Stressors are typically acute (relatively short term) and may include rapid changes in ambient conditions ( e.g ., temperature and depth), physiological disturbance, exhaustion and/or different types and severity of injuries (Breen et al ., 2020 ). Such stressors can result in undesirable outcomes.…”

Section: Introductionmentioning

confidence: 99%

Atlantic mackerel (Scomber scombrus) change skin colour in response to crowding stress

Guro

Anders

Bondø

et al. 2022

Journal of Fish Biology

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Wild capture can be stressful for fish. Stress has the potential to induce mortality in released unwanted catches or negative flesh quality consequences in retained ones.Such effects compromise sustainable natural resource management and industry profitability. Mitigating stress during capture is therefore desirable. Biological indicators of stress can objectively inform fishers as to the functional welfare status of catches during fishing operations. If they are to be of practical use in mitigating stress during wild capture events, such indicators must be quantifiable, respond rapidly, reflect the level of induced stress and be easily observable. Atlantic mackerel (Scomber scombrus) are extensively targeted by purse seine fisheries in European waters but are particularly vulnerable to stress. Excessive crowding in the net is thought to be the principal stress mechanism. There is therefore a need to develop indicators of crowding stress for this species so that catch welfare can be improved.Here, we demonstrate that S. scombrus exhibit a skin colour change from predominately green to predominately blue when exposed to crowding stress. In sea cage trials, we induced various degrees of stress in groups of wild-caught S. scombrus by manipulating crowding density and its duration. Skin colour was quantified in air using digital photography. The colour change occurred rapidly (within the typical duration of crowding events in the fishery), and its magnitude was correlated to the severity and duration of crowding. Bluer fish were also associated with higher levels of plasma lactate. No appreciable colour change was observed in uncrowded (control) groups during the treatment period. Nonetheless, unstressed S. scombrus did turn blue <1 h after death. Together, these results indicate that skin colour change has the potential to be a useful real-time indicator of crowding stress for S. scombrus and could therefore be used to improve welfare during wild capture fishing.

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“…And currently, fish experience practices that are likely to cause suffering, if they are aware. These include shark-finning, live sushi (“ikezukuri”), and globally, the wild-capture fishing that causes significant bodily injury [e.g., ( 166 , 167 )] and affects billions of individual fish ( 168 , 169 ). So, given uncertainty about fish sentience, what should be done?…”

Section: Why Is Sentience Ethically Relevant and What Are The Consequ...mentioning

confidence: 99%

What Is It Like to Be a Bass? Red Herrings, Fish Pain and the Study of Animal Sentience

Mason

Lavery

2022

Front. Vet. Sci.

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Debates around fishes' ability to feel pain concern sentience: do reactions to tissue damage indicate evaluative consciousness (conscious affect), or mere nociception? Thanks to Braithwaite's discovery of trout nociceptors, and concerns that current practices could compromise welfare in countless fish, this issue's importance is beyond dispute. However, nociceptors are merely necessary, not sufficient, for true pain, and many measures held to indicate sentience have the same problem. The question of whether fish feel pain – or indeed anything at all – therefore stimulates sometimes polarized debate. Here, we try to bridge the divide. After reviewing key consciousness concepts, we identify “red herring” measures that should not be used to infer sentience because also present in non-sentient organisms, notably those lacking nervous systems, like plants and protozoa (P); spines disconnected from brains (S); decerebrate mammals and birds (D); and humans in unaware states (U). These “S.P.U.D. subjects” can show approach/withdrawal; react with apparent emotion; change their reactivity with food deprivation or analgesia; discriminate between stimuli; display Pavlovian learning, including some forms of trace conditioning; and even learn simple instrumental responses. Consequently, none of these responses are good indicators of sentience. Potentially more valid are aspects of working memory, operant conditioning, the self-report of state, and forms of higher order cognition. We suggest new experiments on humans to test these hypotheses, as well as modifications to tests for “mental time travel” and self-awareness (e.g., mirror self-recognition) that could allow these to now probe sentience (since currently they reflect perceptual rather than evaluative, affective aspects of consciousness). Because “bullet-proof” neurological and behavioral indicators of sentience are thus still lacking, agnosticism about fish sentience remains widespread. To end, we address how to balance such doubts with welfare protection, discussing concerns raised by key skeptics in this debate. Overall, we celebrate the rigorous evidential standards required by those unconvinced that fish are sentient; laud the compassion and ethical rigor shown by those advocating for welfare protections; and seek to show how precautionary principles still support protecting fish from physical harm.

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Catch Welfare in Commercial Fisheries

Cited by 17 publications

References 124 publications

Physiological response and survival of Atlantic mackerel exposed to simulated purse seine crowding and release

Physiological response and survival of Atlantic mackerel exposed to simulated purse seine crowding and release

Atlantic mackerel (Scomber scombrus) change skin colour in response to crowding stress

What Is It Like to Be a Bass? Red Herrings, Fish Pain and the Study of Animal Sentience

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