Bycatch mitigation assessment for sharks caught in coastal anchored gillnets

Thorpe, Teresa; Frierson, Dargan M. W.

doi:10.1016/j.fishres.2009.04.003

Cited by 34 publications

(48 citation statements)

References 32 publications

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“…Other species‐specific physiological resiliencies to fishing‐and‐discarding mechanisms have been clearly demonstrated in a few multispecies assessments (Thorpe and Frierson ; Frick et al . , ).…”

Section: Reviewmentioning

confidence: 94%

Mitigating unaccounted fishing mortality from gillnets and traps

2013

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Gillnets and traps often are considered to have fewer holistic environmental impacts than active fishing gears. However, in addition to the targeted catches, gillnets and traps still cause unwanted mortalities due to (i) discarding, (ii) ghost fishing of derelict gear, (iii) depredation, (iv) escaping or dropping out of gear, (v) habitat damage, and potentially (vi) avoiding gear and predation and (vii) infection of injuries sustained from most of the above. Population‐level concerns associated with such ‘unaccounted fishing mortalities’ from gillnets and traps have been sufficient to warrant numerous attempts at mitigation. In this article, we reviewed relevant research efforts, locating 130 studies in the primary literature that concomitantly quantified mortalities and their resolution through technical modifications, with the division of effort indicating ongoing concerns. Most studies (85) have focused on discard mortality, followed by ghost‐fishing (24), depredation (10) and escape (8) mortalities. The remaining components have been poorly studied (3). All problematic mortality components are affected by key biological (e.g. species), technical (e.g. fishing mechanisms) and/or environmental (e.g. temperature) factors. We propose that these key factors should be considered as part of a strategy to reduce impacts of these gears by first assessing modifications within and then beyond conventional configurations, followed by changes to operational and handling practices. Justification for this three‐tiered approach is based not only on the potential for cumulative reduction benefits, but also on the likely ease of adoption, legislation and compliance.

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Section: Reviewmentioning

confidence: 94%

Mitigating unaccounted fishing mortality from gillnets and traps

2013

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“…Description the weaves (e.g., using multi-monofilament instead of single monofilament), using larger floats on the top rope and heavier weights or lead-core on the bottom rope, and infusing compounds can make the net stiffer, reducing the likelihood of entangling large organisms [89][90][91]. Deploying driftnets 2 m below instead of at the sea surface, and using highly visible netting in the upper portion of a surface drift gillnet reduced seabird catch rates [92,93].…”

Section: Methodsmentioning

confidence: 99%

Status of international monitoring and management of abandoned, lost and discarded fishing gear and ghost fishing

Gilman

2015

Marine Policy

167

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“…High AVM for Sphyrna spp. has been reported in trawls (97·6%; Fennessy, ), protective nets (98·3%; Reid & Krogh, ) and commercial gillnets (71·5–89·3%; Thorpe & Frierson, ; Braccini et al , ). Even capture in gillnets set for short periods (≤1 h) during scientific studies can result in an AVM of 31–37% (Manire et al , ; Hueter et al , ).…”

Section: Taxonomic Overview Of Elasmobranch Discard Survivalmentioning

confidence: 97%

“…acanthias was 17·5% (19–24 h soak time), but that there was further mortality for at least the next 48 h, resulting in an overall mortality estimate of 55%. Thorpe & Frierson () examined the survivorship of four shark species [Atlantic sharpnose shark Rhizoprionodon terraenovae (Richardson 1836), C . acronotus , C .…”

Section: Discard Mortality Of Elasmobranchs By Gearmentioning

confidence: 99%

A review of capture and post‐release mortality of elasmobranchs

Ellis

Phillips

Poisson

2016

Journal of Fish Biology

135

108

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There is a need to better understand the survivorship of discarded fishes, both for commercial stocks and species of conservation concern. Within European waters, the landing obligations that are currently being phased in as part of the European Union's reformed common fisheries policy means that an increasing number of fish stocks, with certain exceptions, should not be discarded unless it can be demonstrated that there is a high probability of survival. This study reviews the various approaches that have been used to examine the discard survival of elasmobranchs, both in terms of at-vessel mortality (AVM) and post-release mortality (PRM), with relevant findings summarized for both the main types of fishing gear used and by taxonomic group. Discard survival varies with a range of biological attributes (species, size, sex and mode of gill ventilation) as well as the range of factors associated with capture (e.g. gear type, soak time, catch mass and composition, handling practices and the degree of exposure to air and any associated change in ambient temperature). In general, demersal species with buccal-pump ventilation have a higher survival than obligate ram ventilators. Several studies have indicated that females may have a higher survival than males. Certain taxa (including hammerhead sharks Sphyrna spp. and thresher sharks Alopias spp.) may be particularly prone to higher rates of mortality when caught.

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Bycatch mitigation assessment for sharks caught in coastal anchored gillnets

Cited by 34 publications

References 32 publications

Mitigating unaccounted fishing mortality from gillnets and traps

Mitigating unaccounted fishing mortality from gillnets and traps

Status of international monitoring and management of abandoned, lost and discarded fishing gear and ghost fishing

A review of capture and post‐release mortality of elasmobranchs

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