Effect of type of bait on pelagic longline fishery–loggerhead turtle interactions in the Gulf of Gabes (Tunisia)

Echwikhi, Khaled; Jribi, Imed; Bradaï, Mohamed Nejmeddine; Bouaïn, Abderrahmen

doi:10.1002/aqc.1120

Cited by 19 publications

(31 citation statements)

References 19 publications

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“…How this behaviour under laboratory conditions relates to behaviour in the wild during an incidental capture is not known. However, our findings support field observations that the type of bait can influence the loggerhead bycatch rate (Echwikhi et al 2010) and higher loggerhead bycatch rates occur when using pelagic longline gear deploying squid baits compared to gear using mackerel baits (Báez et al 2010).…”

Section: Discussionsupporting

confidence: 85%

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Effects of chemicals from longline baits on the biting behaviour of loggerhead sea turtles

Piovano

Farcomeni

Giacoma

2012

African Journal of Marine Science

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The biting behaviour of the loggerhead sea turtle Caretta caretta, a high bycatch species by longline fishing gear, was studied on 30 wild specimens held temporarily at rescue centres. To account for repeated measures, the data were analysed using mixed-effects models. Chemicals from squid baits elicited significantly more biting behaviour than those from mackerel baits. Smaller turtles were more likely to bite than larger turtles. The findings add increasing evidence in support of the idea that the use of fish baits instead of squid baits could be a conservation measure to protect this endangered species from bycatch. Rescue Centre Laguna di Nora, Italy, pers. comm.), we decided to verify the loggerheads' preference for squid. To determine whether loggerheads were differentially attracted to the chemicals from mackerel and squid baits, we carried out experiments with those baits hidden in sacks, so that loggerheads could not visually recognise them as their usual preys. The focus of our study was to find new evidence concerning the feeding behaviour of wild sea turtles that could help explain reports from observations of longline fishing. Material and methods Choice experimentWe recorded the behaviour of 30 wild loggerhead individuals (22 juveniles and eight adults) held temporarily at the Laguna di Nora and CTS Linosa sea turtle rescue centres, Italy. Their curved carapace length (CCL) ranged between 29 and 82.5 cm (mean CCL = 48.7 cm, SD = 15.5) and all

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Section: Discussionsupporting

confidence: 85%

“…Different types of baits have been tested at sea to verify their effectiveness in mitigating turtle bycatch without affecting the catch of target species (Echwikhi et al 2010 developed and to that end further investigation of the relationships between chemical cues and prey appearance could be of value.…”

Section: Discussionmentioning

confidence: 99%

Effects of chemicals from longline baits on the biting behaviour of loggerhead sea turtles

Piovano

Farcomeni

Giacoma

2012

African Journal of Marine Science

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“…For example, Mejuto et al (2008) observed higher catch rates of loggerhead and olive ridley sea turtles on pieces of blue shark for bait than with squid or mackerel for bait. Echwikhi et al (2010) observed significantly lower loggerhead turtle catch rates with pieces of stingray used for bait versus whole mackerel.…”

Section: Bait Typementioning

confidence: 86%

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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“…The FAO guidelines require longline fisheries to develop and implement modifications in hook design, bait species, depth, gear specifications and fishing practices in order to minimize sea turtle incidental bycatch and mortality (FAO, 2005). Recently, trials using different types of bait have been used as a mitigation method to reduce sea turtle bycatch in longline fisheries (Swimmer et al, 2005;Watson et al, 2005;Yokota et al, 2009;Echwikhi et al, 2010).…”

Section: Pelagic Longline -Sea Turtle Interactionsmentioning

confidence: 99%

“…In fact, evaluation of the potential impacts of bait modifications on the catch efficiency for target and non-target species is necessary (Swimmer et al, 2005;Gilman et al, 2006b;Yokota et al, 2009;Echwikhi et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Effect of bait on sea turtles bycatch rates in pelagic longlines: An overview

et al. 2011

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Pelagic longline fishing has been identified as a significant threat to endangered sea turtle populations. Reducing sea turtle bycatch in pelagic longline fisheries, in concert with activities to reduce other anthropogenic mortality sources, may halt and reverse population declines. Here, we examine the effect of bait manipulation as a simple mitigation method that could reduce sea turtle interactions with longline fishing gear. We analyzed laboratory experiments and field trials conducted in the Mediterranean, the northeast Distant Area in the Atlantic and the Western North Pacific. Studies showed that turtles are more likely to feed on squid than on mackerel when both are used simultaneously as bait. The stingray, Dasyatis pastinaca, used as bait, was more effective than mackerel; this ray was vulnerable and stimulated much thought about other species to use as alternative bait. Effective in laboratory conditions with captive turtles, dyed and artificial bait did not seemed to be effective in reducing turtle bycatch in field conditions. Optimal mitigation measure must reduce incidence of hooking of threatened sea turtles to acceptable levels and also offer an economic advantage to fisheries. Studies concerning the effect of bait modification to reduce turtle bycatch highlight the importance of an integrated approach towards sensory deterrents, as both visual and chemical cues are likely to attract sea turtles to longline gear. Further research on the development of sensory-based deterrents can contribute to reduced sea turtle bait interactions and maintain catch rates of target species.

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Effect of type of bait on pelagic longline fishery–loggerhead turtle interactions in the Gulf of Gabes (Tunisia)

Cited by 19 publications

References 19 publications

Effects of chemicals from longline baits on the biting behaviour of loggerhead sea turtles

Effects of chemicals from longline baits on the biting behaviour of loggerhead sea turtles

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

Effect of bait on sea turtles bycatch rates in pelagic longlines: An overview

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