Rapid Assessments of Leatherback Small-Scale Fishery Bycatch in Internesting Areas in the Eastern Pacific Ocean

Ortiz‐Alvarez, Clara; Pajuelo, Mariela; Grados, Daniel; Abrego, Marino; Barragán-Rocha, Ana Rebeca; Barrantes, Mariano; Sánchez, Alejandro Cotto; Fonseca, Luis G.; Espinal, Velkiss Gadea; Mangel, Jeffrey C.; Rguez‐Baron, Juan M.; Santidrian-Tomillo, Pilar; Sarti, Laura; Santana-Hernández, Heriberto; Shillinger, George L.; Prado, Myriam; Wallace, Bryan P.; Williard, Amanda Southwood; Zavala‐Norzagaray, Alan A.; Alfaro‐Shigueto, Joanna

doi:10.3389/fmars.2019.00813

Cited by 7 publications

(3 citation statements)

References 42 publications

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“…The efficiency of lights is influenced by local environmental factors (Wang et al 2013), so it is important to test net illumination in multiple locations with different sea turtle species. These tests are especially vital for the leatherback turtle, which is critically endangered in the Pacific Ocean and primarily threatened by gillnet fisheries (Alfaro-Shigueto et al 2018;Ortiz-Alvarez et al 2020). This population requires immediate bycatch reduction to prevent extirpation (Laúd OPO Network 2020).…”

Section: Introductionmentioning

confidence: 99%

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Gillnet illumination as an effective measure to reduce sea turtle bycatch

Allman

Agyekumhene

Stemle

2020

Conservation Biology

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The growing demand for fish around the world is an immediate threat to marine megafauna that are unintentionally captured in commercial and artisanal fishery operations. Bycatch mitigation strategies, such as turtle excluder devices, circle hooks, and net illumination, have successfully reduced this risk in some fisheries. We explored the effectiveness of gillnet illumination to reduce sea turtle captures in 2 artisanal fisheries (Mankoadze and Winneba, Ghana) under normal fishing conditions. We first quantified sea turtle bycatch in Ghana's artisanal gillnet fishery from 15 boats for 12 months. We then quantified catch of targeted species and sea turtle bycatch from 20 boats for 15 months (7427 net sets). For 10 of these boats, we placed a Centro Economy green light (1 LED) at each 10-m interval on the net. We also quantified target catch and sea turtle bycatch from 30 boats for 8 months (2250 net sets). In 15 of these boats, a Centro Deluxe green light (3 LEDs) was installed at 15-m intervals. Boats with economy lights and those with deluxe lights both exhibited an 81% decrease in sea turtle captures (W = 1, p < 0.001, n = 20; W = 215, p < 0.001, n = 30, respectively) compared with control boats without lights. Illuminated nets resulted in fewer turtle catches for leatherback (Dermochelys coriacea), olive ridley (Lepidochelys olivacea), and green sea turtles (Chelonia mydas) (p < 0.05 for all species). Target catch (mass) (W = 53, p = 0.853 n = 20; W = 76, p = 0.449, n = 23) and value (W = 50, p = 1, n = 20; W = 69, p = 0.728, = 23) were not different across treatments. Our study affirms net illumination can reduce capture rates of 3 species of sea turtles, including the imperiled leatherback. Gear modification methods can successfully reduce bycatch if they are affordable and have broad applications for multiple species in different fisheries.

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Section: Introductionmentioning

confidence: 99%

“…2018; Ortiz‐Alvarez et al. 2020). This population requires immediate bycatch reduction to prevent extirpation (Laúd OPO Network 2020).…”

Section: Introductionmentioning

confidence: 99%

Gillnet illumination as an effective measure to reduce sea turtle bycatch

Allman

Agyekumhene

Stemle

2020

Conservation Biology

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“…Recreational boaters account for the majority of vessels in Massachusetts, likely contributing to the high number of opportunistic reports from this group. Direct solicitation of reports from commercial fishers via dockside interviews, surveys, and reporting hotlines has been successfully used to assess fishery bycatch elsewhere (Martin & James 2005, Lee Lum 2006, Peckham et al 2007, Moore et al 2010, Alfaro-Shigueto et al 2018, Ortiz-Alvarez et al 2020. In Atlantic Canada, just north of our study area, over 70% of the entanglement reports come from commercial fishers (Martin & James 2005, Hamelin et al 2017.…”

Section: Discussionmentioning

confidence: 99%

Disentanglement network data to characterize leatherback sea turtle Dermochelys coriacea bycatch in fixed-gear fisheries

Dodge¹,

Landry²,

Lynch³

et al. 2022

Endang. Species. Res.

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To characterize sea turtle bycatch in fixed-gear fisheries in Massachusetts, USA, we analyzed a 15 yr dataset of entanglement reports and detailed documentation from disentanglement operations. Almost all (272) of the 280 confirmed entanglements involved leatherback turtles Dermochelys coriacea. The majority of turtles were entangled in actively fished (96%), commercial (94%) pot/trap gear with unbroken/untriggered weak links, specifically the buoy lines marking lobster, whelk, and fish traps. Most reports came from recreational boaters (62%) and other sources (26%), rather than commercial fishers (12%). Leatherback entanglements occurred from May to November, with peak reporting in August, and included adult males, adult females, and subadults. All entanglements involved the turtle’s neck and/or front flippers, with varying degrees of visible injuries; 47 entangled leatherbacks were dead in gear, 224 were alive at first sighting, and 1 case was unknown. Post-release monitoring suggested turtles can survive for days to years after disentanglement, but data were limited. While the observed entanglements in our study are low relative to global bycatch, these numbers should be considered a minimum. Our findings are comparable to observed numbers of leatherbacks taken in Canadian fixed-gear fisheries, and represent just one of multiple, cumulative threats in the North Atlantic. Managers should focus on strategies to reduce the co-occurrence of sea turtles and fixed-fishing gear, including reductions in the number of buoy lines allowed (e.g. replace single sets with trawls), seasonal and area closures targeted to reduce sea turtle-gear interaction, and encourage the development of emerging technologies such as ‘ropeless’ fishing.

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