Effects of 16/0 Circle Hooks on Pelagic Fish Catches in Three South Pacific Albacore Longline Fisheries

Beverly, S.; Curran, Daniel S.

doi:10.5343/bms.2011.1060

Cited by 14 publications

(20 citation statements)

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“…). Unlike J‐shaped J and tuna hooks, which tend to result in deep hooking, circle hooks (circular or oval in shape, the point is turned perpendicularly back towards the shank, making the point less exposed relative to J‐shaped J and tuna hooks) with little or no offset, when swallowed, tend not to initially hook an organism, but instead, as the organism pulls and turns away from the leader, this pulls on and rotates the circle hook and the hook slides over soft tissue as the eye of the hook exits the mouth, causing the hook's point to typically catch in the corner of the organism's mouth (Cooke and Suski ; Curran and Beverly ; Epperly et al . ; Clarke et al .…”

Section: Discussionmentioning

confidence: 99%

“…Larger hooks reduce the relative catchability of species and sizes of organisms with relatively small mouths and that tend to be caught by ingesting a baited hook, where the larger the hook, the lower the probability that these smaller mouthed organisms can fit it in their mouths (Piovano et al . , ; Curran and Beverly ; Yokota et al . ; Gilman and Hall ).…”

Section: Discussionmentioning

confidence: 99%

“…b) or other species (Gilman and Hall ). Hook width, however, has been observed to significantly affect haulback disposition of some pelagic fishes (Curran and Beverly ) (Fig. b).…”

Section: Discussionmentioning

confidence: 99%

“…Tuna hooks have a slightly curved shaft, and like J hooks, the point is not protected by the shaft, and as a result, tuna hooks have been categorized as a type of J-shaped hook (Serafy et al 2009). Unlike J-shaped J and tuna hooks, which tend to result in deep hooking, circle hooks (circular or oval in shape, the point is turned perpendicularly back towards the shank, making the point less exposed relative to J-shaped J and tuna hooks) with little or no offset, when swallowed, tend not to initially hook an organism, but instead, as the organism pulls and turns away from the leader, this pulls on and rotates the circle hook and the hook slides over soft tissue as the eye of the hook exits the mouth, causing the hook's point to typically catch in the corner of the organism's mouth (Cooke and Suski 2004;Curran and Beverly 2012;Epperly et al 2012;Clarke et al 2014). Due to the prevalent hooking location, relative to using J-shaped hooks, using circle hooks might result in a higher incidence of catch being alive upon haulback and result in less trauma, increasing the probability of post-release survival of organisms released alive (Horodysky and Graves 2005;Kerstetter and Graves 2006;Carruthers et al 2009;Serafy et al 2009Serafy et al , 2012aGilman and Hall 2015).…”

Section: Hook Shapementioning

confidence: 99%

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A cross‐taxa assessment of pelagic longline by‐catch mitigation measures: conflicts and mutual benefits to elasmobranchs

et al. 2016

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Elasmobranch mortality in pelagic longline fisheries poses a risk to some populations, alters the distribution of abundance between sympatric competitors, changing ecosystem structure, processes and stability. Individual and synergistic effects on elasmobranch catch and survival from pelagic longline gear factors, including methods prescribed to mitigate bycatch of other vulnerable taxa, were determined. Overall relative risk of higher circle vs. J-shaped hook shark catch rates conditioned on potentially informative moderators, from 30 studies, was estimated using an inverse-precision weighted mixed-effects meta-regression modelling approach. Sharks had a 1.20 times (95% CI: 1.03-1.39) significantly higher pooled relative risk of capture on circle hooks, with two significant moderators. The pooled relative risk estimate of ray circle hook catch from 15 studies was not significant (RR = 1.22, 95% CI: 0.89-1.66) with no significant moderators. From a literature review, wire leaders had higher shark catch and haulback mortality than monofilament. Interacting effects of hook, bait and leader affect shark catch rates: hook shape and width and bait type determine hooking position and ability to sever monofilament leaders. Circle hooks increased elasmobranch catch, but reduced haulback mortality and deep hooking relative to J-shaped hooks of the same or narrower width. Using fish vs. squid for bait increased shark catch and deep hooking. Pelagic stingray (Pteroplatytrygon violacea) catch and mortality were lower on wider hooks. Using circle instead of J-shaped hooks and fish instead of squid for bait, while benefitting sea turtles, odontocetes and possibly seabirds, exacerbates elasmobranch catch and injury, therefore warranting fishery-specific assessments to determine relative risks.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…b) or other species (Gilman and Hall ). Hook width, however, has been observed to significantly affect haulback disposition of some pelagic fishes (Curran and Beverly ) (Fig. b).…”

Section: Discussionmentioning

confidence: 99%

Section: Hook Shapementioning

confidence: 99%

See 2 more Smart Citations

A cross‐taxa assessment of pelagic longline by‐catch mitigation measures: conflicts and mutual benefits to elasmobranchs

et al. 2016

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show abstract

“…The less exposed points of circle hooks reduce the probability of foul-hooking organisms. When ingested, J-shaped hooks tend to result in deep hookings, while circle hooks with little or no offset tend to catch in the corner of the mouth (Cook and Suski 2004;Curran and Beverly 2012;Epperly et al 2012;Clarke et al 2014;Parga et al 2015). Due to the prevalent hooking location, circle hooks might result in higher pre-catch 1 and haulback survival rates, make it easier for crew to remove all terminal tackle, and thus increase the probability of post-release survival for turtles released alive (Chaloupka et al 2004;Cooke and Suski 2004;Godin et al 2012;Serafy et al 2012;Swimmer and Gilman 2012;Parga et al 2015).…”

Section: Hook Shapementioning

confidence: 99%

Review of effects of pelagic longline hook and bait type on sea turtle catch rate, anatomical hooking position and at-vessel mortality rate

Gilman

Huang

2016

Rev Fish Biol Fisheries

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Review of effects of pelagic longline hook and bait type on sea turtle catch rate, anatomical hooking position and at-vessel mortality rate WCPFC-SC13-2017/ EB-IP-01Gilman, E 1 . and H-W. Abstract Bycatch in pelagic longline fisheries is one of the most serious threats to some sea turtle populations. Hook shape, hook minimum width and bait type have been the focus of research and management measures to mitigate problematic bycatch of vulnerable taxa. To assess the current state of knowledge and progress over the past decade, we reviewed findings on the effects of hook and bait type on pelagic longline sea turtle catch rates, anatomical hooking position and at-vessel mortality. Fish versus squid for bait lowered catch rates of leatherback sea turtles (Dermochelys coriacea) and individual species of hard shelled turtles. Fish bait also reduced hard-shelled turtle deep hooking. Wider circle hooks reduced both leatherback and hard-shelled turtle catch rates relative to narrower J and tuna hooks, and reduced the proportion of caught hard-shelled turtles that were deeply hooked. Wider circle hooks with fish bait reduced leatherback and hard-shelled turtle catch rates relative to narrower J and tuna hooks with squid bait. Wider versus narrower circle hooks reduced hard-shelled sea turtle catch rates and deep hooking. The mechanisms for hook and bait type effects on turtle interactions are reviewed. Research designed to assess single factor effects is needed, in particular for hook shape and minimum width, and for hook and bait effects on anatomical hooking position and survival rates. Fishery-specific and holistic assessments are needed to account for variability between fisheries in a bycatch mitigation method's commercial viability, relative risks to affected populations and possible conflicting effects on vulnerable taxa.

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Standardized catch and survival rates, and effect of a ban on shark retention, Palau pelagic longline fishery

Gilman

Chaloupka

Merrifield³

et al. 2015

Aquatic Conservation

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1. Pelagic longline fisheries affect both market and vulnerable bycatch species and can have broad effects on community structure and processes.2. Observer data from the Palau longline fishery were analysed to identify opportunities to mitigate vulnerable species bycatch, determine temporal trends in local abundance, and assess changes following a ban on shark retention and wire leaders. Catch and haulback condition data for bigeye and yellowfin tunas, blue and silky sharks and pelagic stingrays were fitted to standardized catch and survival rate models.3. The fishery caught silky and blue sharks, olive ridley sea turtles and other species of conservation concern. 4. Changing from shallow sets to deep daytime sets might reduce shark and sea turtle catch rates but increase turtle haulback mortality rates, maintain economically viable tuna catch rates, but increase catch rates of pelagic stingrays, a lower conservation concern than main caught species of sharks and turtles. 5. Focusing fishing effort during the middle of the calendar year would maximize yellowfin tuna and minimize silky shark standardized catch rates, but maximize blue shark catch rates. 6. A large decline in shark fishing mortality rate very likely occurred following a ban on shark retention and wire leaders. This was due to large reductions in the nominal shark catch rate and shark retention, partially offset by decreases in the shark haulback survival rate and pre-catch survival rate. Significantly higher blue shark and lower pelagic stingray nominal catch rates occurred on wire vs. monofilament leaders. Significantly higher blue shark and lower yellowfin tuna nominal catch rates occurred on sets using shallow 'shark lines'. It is a research priority to compare the probability of shark pre-catch survival after escaping from monofilament leaders with an ingested hook and trailing line to the survival probability when captured on wire leaders.

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Effects of 16/0 Circle Hooks on Pelagic Fish Catches in Three South Pacific Albacore Longline Fisheries

Cited by 14 publications

References 0 publications

A cross‐taxa assessment of pelagic longline by‐catch mitigation measures: conflicts and mutual benefits to elasmobranchs

A cross‐taxa assessment of pelagic longline by‐catch mitigation measures: conflicts and mutual benefits to elasmobranchs

Review of effects of pelagic longline hook and bait type on sea turtle catch rate, anatomical hooking position and at-vessel mortality rate

Standardized catch and survival rates, and effect of a ban on shark retention, Palau pelagic longline fishery

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