Mitigating bycatch in tuna fisheries

Hall, Martín; Gilman, Eric; Minami, Hiroshi; Mituhasi, Takahisa; Carruthers, Erin H.

doi:10.1007/s11160-017-9478-x

Cited by 47 publications

(47 citation statements)

References 155 publications

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“…Brailing small groups of fish will reduce the individual sorting times, and thus air exposure times. Other means to expedite sorting and reduce exhaustion, air exposure and injury potential include the use of overboard wet chutes, which are employed in some commercial purse seine fisheries either voluntarily (e.g., Pacific salmon; Watson, Cook, Young, & Hinch, ) or by regulation (e.g., tuna; Poisson et al., ), conveyor belts, or by providing shade and/or water spraying (Hall et al., ). Efforts to improve the design and efficiency of on‐deck sorting systems will improve the condition of fish passing through them, but there has been little published research to substantiate these claims.…”

Section: Capture Stressors and Their Mitigation Potential By Fishing mentioning

confidence: 99%

“…As a novel means to eliminate brailing (and crushing injuries) in tuna purse seine fisheries, Hall et al. () describe fish pumps that deposit live fish on deck for sorting.…”

Section: Capture Stressors and Their Mitigation Potential By Fishing mentioning

confidence: 99%

“…Reducing handling times is the most practical means to improve survival through a reduction in air exposure and exhaustion. Prioritizing by-catch during sorting (Poisson, Séret, Vernet, Goujon, & Dagorn, 2014;Raby, Packer, et al, 2014) or before brailing (with larger by-catch species; Hutchinson, Itano, Muir, & Holland, 2015;Hall et al, 2017) to expedite their release can be effective. Having the vessel equipped with a canvas sling is a similar solution for the safe release of large by-catch species reducing risk of injury (Poisson et al, 2014).…”

Section: Mitigation Optionsmentioning

confidence: 99%

“…Efforts to improve the design and efficiency of on-deck sorting systems will improve the condition of fish passing through them, but there has been little published research to substantiate these claims. As a novel means to eliminate brailing (and crushing injuries) in tuna purse seine fisheries, Hall et al (2017) describe fish pumps that deposit live fish on deck for sorting.…”

Section: Mitigation Optionsmentioning

confidence: 99%

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A synthesis to understand responses to capture stressors among fish discarded from commercial fisheries and options for mitigating their severity

et al. 2018

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Discarding non‐target fish from commercial fisheries is controversial and has been a persistent concern for fisheries managers globally. Discard management strategies typically begin by understanding mortality rates among discarded fish, a challenging task given the dynamic, highly context‐specific nature of fisheries. An alternative is to develop our knowledge of how stressors operate by first understanding the causes of mortality that drive this context dependence. Particularly relevant to mitigation efforts is an understanding of how fish respond to the physical factors of fishing, such as the gear itself and methods of fishing and handling the gear. We provide a synthesis of how commercial fishing methods may influence discard mortality and outline means by which capture‐induced stress and injury can be mitigated for common commercial gear types, emphasizing method variants or alternatives during capture, handling, and release that could improve survival. This synthesis identifies exhaustion and injury as the most detrimental and ubiquitous stressors experienced by discarded fish, with few options for mitigating their effects. Trawls and hanging net fisheries are identified as the most harmful gears for by‐catch, characterized by high stress regardless of method variants and limited options for mitigation. Irrespective of gear type and type of stressor, minimizing durations of capture and handling and encouragement of good handling behaviour (e.g., during landing and sorting) will reduce the magnitude of stress and injury in fish, and ultimately increase survival.

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Section: Capture Stressors and Their Mitigation Potential By Fishing mentioning

confidence: 99%

“…As a novel means to eliminate brailing (and crushing injuries) in tuna purse seine fisheries, Hall et al. () describe fish pumps that deposit live fish on deck for sorting.…”

Section: Capture Stressors and Their Mitigation Potential By Fishing mentioning

confidence: 99%

Section: Mitigation Optionsmentioning

confidence: 99%

Section: Mitigation Optionsmentioning

confidence: 99%

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A synthesis to understand responses to capture stressors among fish discarded from commercial fisheries and options for mitigating their severity

et al. 2018

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“…Thus, relative to J-shaped hooks of the same minimum width, circle hooks benefit sea turtles (both hardshelled species and leatherbacks) because a smaller proportion of those captured will be deeply hooked, and because they reduce leatherback sea turtle catch rates. However, use of circle hooks in place of similar sized J-shaped hooks will provide little benefit to hardshelled turtles in deep-set longline fisheries where most turtles drown during the gear soak and are dead upon gear haulback (e.g., Gilman et al 2006c;Clarke et al 2014;Hall et al 2017).…”

Section: Pelagic Longline Hook Shapementioning

confidence: 99%

Robbing Peter to pay Paul: replacing unintended cross-taxa conflicts with intentional tradeoffs by moving from piecemeal to integrated fisheries bycatch management

Gilman

Chaloupka

Dagorn

et al. 2019

Rev Fish Biol Fisheries

Self Cite

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Bycatch in fisheries can have profound effects on the abundance of species with relatively low resilience to increased mortality, can alter the evolutionary characteristics and concomitant fitness of affected populations through heritable trait-based selective removals, and can alter ecosystem functions, structure and services through food web trophic links. We challenge current piecemeal bycatch management paradigms, which reduce the mortality of one taxon of conservation concern at the unintended expense of others. Bycatch mitigation measures may also reduce intraspecific genetic diversity. We drew examples of broadly prescribed 'best practice' methods to mitigate bycatch that result in unintended cross-taxa conflicts from pelagic longline, tuna purse seine, gillnet and trawl fisheries. We identified priority improvements in data quality and in understanding ecological effects of bycatch fishing mortality to support holistic ecological risk assessments of the effects of bycatch removals conducted through semi-quantitative and model-based ().,-volV) ( 01234567 89().,-volV) approaches. A transition to integrated bycatch assessment and management that comprehensively consider biodiversity across its hierarchical manifestations is needed, where relative risks and conflicts from alternative bycatch management measures are evaluated and accounted for in fisheries decision-making processes. This would enable managers to select measures with intentional and acceptable tradeoffs to best meet objectives, when conflicts are unavoidable.

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A review of reported effects of pelagic longline fishing gear configurations on target, bycatch and vulnerable species

Santos,

Rosa,

Gonçalves

et al. 2023

Aquatic Conservation

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A meta‐analysis of 40 publications totalling 59 experiments was undertaken to review and assess the effects of changing the hook (circle vs. J‐hooks or tuna hooks), bait (fish vs. squid) and leader (wire vs. nylon) type on retention and at‐haulback mortality rates of teleosts (tunas and billfishes), elasmobranchs and sea turtles caught on shallow‐set and deep‐set pelagic longline fisheries. Circle hooks are a promising approach to mitigate the impact of pelagic longline fisheries on sea turtles, as they reduced sea turtle retention rates. The adoption of circle hooks would, however, also lead to a decrease in swordfish retention, the main target species of shallow‐set pelagic longlines. Using fish as bait resulted in lower retention rates of sea turtles, highlighting that option as an additional measure to further mitigate sea turtle bycatch. The bait type had non‐significant effects on sharks, except for blue shark and shortfin mako, for which at‐haulback mortality rates were significantly higher with fish bait. The use of nylon leaders instead of wire leaders could serve as a conservation measure for sharks, as they reduced the retention of blue shark without adversely impacting the catches of swordfish. The results on the effect of the leader material types should, however, be interpreted with caution owing to the limited information available reporting on leader material effects. When considering future research directions, priority should be given to experimental field work on the effects of leader material and on deep‐set longlines. Evaluating the post‐release survival of species should also be a priority.

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Mitigating bycatch in tuna fisheries

Cited by 47 publications

References 155 publications

A synthesis to understand responses to capture stressors among fish discarded from commercial fisheries and options for mitigating their severity

A synthesis to understand responses to capture stressors among fish discarded from commercial fisheries and options for mitigating their severity

Robbing Peter to pay Paul: replacing unintended cross-taxa conflicts with intentional tradeoffs by moving from piecemeal to integrated fisheries bycatch management

A review of reported effects of pelagic longline fishing gear configurations on target, bycatch and vulnerable species

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