Effects of 17/0 circle hooks and bait on sea turtles bycatch in a Southern Atlantic swordfish longline fishery

Santos, Miguel N.; Coelho, Rui; Fernandez‐Carvalho, Joana; Amorim, Sérgio

doi:10.1002/aqc.2324

Cited by 12 publications

(16 citation statements)

References 42 publications

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“…Santos et al . () concluded that significant reduction of bycatch of sea turtles, particularly for loggerheads ( Caretta caretta ) can be achieved in the Southern Atlantic by changing from J‐hooks to circle hooks, especially if baited with mackerel. As the voluntary adoption of circle hooks is more likely to happen if catch rates of target species are unaffected or increased, the effects of hook styles and bait types on the retained catch were addressed in the present study.…”

Section: Discussionmentioning

confidence: 99%

“…The main object of the SELECT-PAL project was to assess the effects of different hook styles and bait type combinations on the catch rates and mortality of sea turtles, as these are an important vulnerable megafauna bycatch component of the Portuguese pelagic longline fishery operating in the Atlantic Ocean. Santos et al (2013) concluded that significant reduction of bycatch of sea turtles, particularly for loggerheads (Caretta caretta) can be achieved in the Southern Atlantic by changing from J-hooks to circle hooks, especially if baited with mackerel. As the voluntary adoption of circle hooks is more likely to happen if catch rates of target species are unaffected or increased, the effects of hook styles and bait types on the retained catch were addressed in the present study.…”

Section: Discussionmentioning

confidence: 99%

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Effects of 17/0 circle hooks and bait on fish catches in a Southern Atlantic swordfish longline fishery

Amorim

Santos

Coelho

et al. 2014

Aquatic Conservation

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ABSTRACT1. This paper reports the results of using different hook style and bait type combinations on the catches of targeted, bycatch and discarded fishes in the Portuguese commercial longline fishery targeting swordfish (Xiphias gladius) in the South Atlantic Ocean.2. In total, 310 longline experimental sets (446 400 hooks) were deployed between October 2008 and February 2012. Three different hook styles were tested; the traditional J-hook (9/0) 10 o offset was compared with two 17/0 circle hooks (a non-offset and a 10 o offset), and squid (Illex spp.) bait was compared with mackerel (Scomber spp.).3. Catch per unit effort (CPUE) was calculated for each fish species per fishing set and compared between the different hook style and bait type combinations. Results indicated that the effects of hook style and bait on the CPUEs were species-specific. For example, swordfish (target species, Xiphias gladius) CPUEs were higher with J-hooks baited with squid, while for the blue shark (most important bycatch species, Prionace glauca) the highest CPUEs were obtained with circle hooks baited with mackerel. For tuna (Thunnus spp.) and marlin (blue, Makaira nigricans and white, Kajikia albida) only the bait effect was significant, with higher catches with squid.4. For the discarded species, the proportions of alive vs dead specimens at the time of fishing gear retrieval were also species-specific. 5. The total retained catch value per unit of effort (VPUE) did not changed between the different hook and bait combinations, but these VPUEs are highly dependent on market fluctuations.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Effects of 17/0 circle hooks and bait on fish catches in a Southern Atlantic swordfish longline fishery

Amorim

Santos

Coelho

et al. 2014

Aquatic Conservation

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“…Furthermore, due to their predominant hooking location, organisms captured on circle hooks that will be handled and released require less handling time, minimizing stress (Cooke and Suski 2004). However, circle hooks are harder to remove and may result in more damage when removed relative to J-shaped hooks that are lodged in the same anatomical location (Santos et al 2013). …”

Section: Hook Shapementioning

confidence: 99%

“…Three were on catch rates (two on leatherbacks, one olive ridleys, Mejuto et al 2008;Coelho et al 2015), five on the proportion deeply hooked (three on loggerheads, two on leatherbacks, Watson et al 2005;Epperly et al 2012;Santos et al 2013;Coelho et al 2015), and four on at-vessel mortality rates (three on leatherbacks, one on loggerheads, Gilman et al 2007;Santos et al 2013;Coelho et al 2015). Most of these findings on bait type effect were from studies with simultaneous variability in hook shape and/or hook minimum width.…”

mentioning

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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“…Although the use of circle-hooks have been a promising method to reduce sea turtle by-catch in some long line fisheries (Santos et al 2013; Watson et al 2005; Sales et al 2010; Gilman et al 2007). there is variability in its effectiveness in Atlantic fleets (Huang et al 2016; Foster et al 2012; Fernandez-Garvalho et al 2015; Richards et al 2012).…”

Section: Potential Sea Turtle By-catch Mitigation Measures For Long Lmentioning

confidence: 99%

Methods to Reduce Sea Turtle Interactions in the Atlantic Canadian Pelagic Long Line Fleet

2017

Preprint

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This project investigates the role of fisheries management in the conservation of loggerhead (Caretta caretta) and leatherback sea turtles (Dermochelys coriacea), both of which are currently listed as vulnerable by the IUCN (International Union for Conservation of Nature). These species migrate from nesting grounds in South America to feed on gelatinous zooplankton (jellyfish) in the North Atlantic off the coast of the United States and Canada. The seasonal foraging grounds of sea turtles heavily overlap with areas of high fishing effort for the longline tuna and swordfish fleet, a fishery that has significantly high rates of sea turtle incidents. The dynamic nature of sea turtle foraging patterns renders static spatio-temporal fishing area closures ineffective. Rather, turtle by-catch mitigation requires small-scale, event-triggered closures and decentralized management to reduce incidents while minimizing the negative socio-economic impact of area closures on fishermen. A number of methods that increase fishing selectivity have been implemented in other commercial fisheries around the globe and are suggested for the Atlantic Canadian fleet moving forward.

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Effects of 17/0 circle hooks and bait on sea turtles bycatch in a Southern Atlantic swordfish longline fishery

Cited by 12 publications

References 42 publications

Effects of 17/0 circle hooks and bait on fish catches in a Southern Atlantic swordfish longline fishery

Effects of 17/0 circle hooks and bait on fish catches in a Southern Atlantic swordfish longline fishery

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

Methods to Reduce Sea Turtle Interactions in the Atlantic Canadian Pelagic Long Line Fleet

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