Post-capture movements of loggerhead turtles in the southeastern Pacific Ocean assessed by satellite tracking

Mangel, Jeffrey C.; Alfaro‐Shigueto, Joanna; Witt, Matthew J.; Dutton, Peter H.; Seminoff, Jeffrey A.; Godley, Brendan J.

doi:10.3354/meps09152

Cited by 21 publications

(14 citation statements)

References 70 publications

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“…Although this constitutes large numbers, most are captured alive and released. Nevertheless, limited information on the post‐release mortality rate and the possible cumulative impacts of multiple captures complicates any attempts to fully understand the impact of this fishery (Mangel et al. in press).…”

Section: Discussionmentioning

confidence: 99%

Small‐scale fisheries of Peru: a major sink for marine turtles in the Pacific

Alfaro‐Shigueto

Mangel

Bernedo³

et al. 2011

Journal of Applied Ecology

115

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Summary 1.Over the last few decades, evidence of marine vertebrate bycatch has been collected for a range of industrial fisheries. It has recently been acknowledged that large impacts may also result from similar interactions with small-scale fisheries (SSF) due largely to their diffuse effort and large number of vessels in operation. Marine mammals, seabirds, turtles as well as some shark species have been reported as being impacted by SSF worldwide. 2. From 2000 to 2007, we used both shore-based and onboard observer programmes from three SSF ports in Peru to assess the impact on marine turtles of small-scale longline, bottom set nets and driftnet fisheries. 3. We reported a total of 807 sea turtles captured, 91AE8% of which were released alive. For these three sites alone, we estimated c. 5900 turtles captured annually (3200 loggerhead turtles Caretta caretta, 2400 green turtles Chelonia mydas, 240 olive ridleys Lepidochelys olivacea and 70 leatherback turtles Dermochelys coriacea). 4. SSF in Peru are widespread and numerous (>100 ports, >9500 vessels, >37 000 fishers), and our observed effort constituted c. 1% of longline and net deployments. We suggest that the number of turtles captured per year is likely to be in the tens of thousands. Thus, the impacts of Peruvian SSF have the potential to severely impact sea turtles in the Pacific especially green, loggerhead and leatherback turtles. 5. Implications of the human use of turtle products as 'marine bushmeat' are also raised as an important issue. Although such utilization is illegal, it is difficult to foresee how it can be managed without addressing the constraints to the livelihoods of those depending almost entirely on coastal resources. 6. Syntheses and applications. Our analysis demonstrates that, despite logistical challenges, it is feasible to estimate the bycatch per unit of effort in SSF by combining methods that account for fishing effort and bycatch, such as using onboard and shore-based observers. We highlight sea turtle bycatch in SSF in the southeast Pacific as a major conservation concern but also suggest possible paths for mitigation.

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Section: Discussionmentioning

confidence: 99%

Small‐scale fisheries of Peru: a major sink for marine turtles in the Pacific

Alfaro‐Shigueto

Mangel

Bernedo³

et al. 2011

Journal of Applied Ecology

115

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“…In fisheries where fishers routinely retrieve hooks from turtles, hook removal from deeply-hooked turtles is more likely to be lethal than removal from externally-and mouth-hooked turtles (Parga et al 2015). However, when best practice handling and release practices are employed, such as removing as much trailing line as possible, both deeply and non-deeply hooked turtles released with a retained hook have been observed to survive (Mangel et al 2011;Parga 2012;Swimmer and Gilman 2012;Swimmer et al 2014). Haulback disposition enables an assessment of the effect of combinations of gear components on mortality rates and an indication of pre-catch and post-release probability of mortality.…”

Section: Introductionmentioning

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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“…The primary limitation in bycatch estimates is the lack of reliable comprehensive information on total fisheries effort, bycatch in small-scale fisheries (Wallace et al 2010, Casale 2011, and the rate of survivorship of released animals (Chaloupka et al 2004, Mangel et al 2011. The rate of survivorship following interaction is considered to be one of the main obstacles to understanding the true impact of fisheries on sea turtle populations (Lewison et al 2013).…”

Section: Introductionmentioning

confidence: 99%