Survival on the rocks: high bycatch in lobster gillnet fisheries threatens hawksbill turtles on rocky reefs along the Eastern Pacific coast of Central America

Abstract

ABSTRACT. Small-scale coastal fisheries can cause detrimental impacts to non-target megafauna through bycatch. This can be particularly true when high-use areas for such species overlap with fishing grounds, as is the case with hawksbill turtle (Eretmochelys imbricata) aggregations at lobster gillnet fishing sites in El Salvador and Nicaragua. We quantified hawksbill bycatch by partnering with local fishers to record data for 690 gillnet sets on rocky reefs at Los Cóbanos Reef Marine Protected Area ) and Punta Amapala (2012 in El Salvador, and La Salvia (2012)(2013)(2014) in Nicaragua. Based on 31 observed hawksbill captures, the mean bycatch-per-unit-effort (0.0022; individuals per set = 0.0450) and mortality (0.74) are among the highest reported for the species across fishing gear types and oceanic regions worldwide, and we conservatively estimate that at least 227 juvenile hawksbill captures occurred in lobster gillnet fishing fleets at our sites during the study. Estimated mortality for the 227 hawksbills -which could approach the 74% observed mortality of total capturesfrom interactions with lobster gillnet fisheries at these sites during the study period may constitute the greatest single source of human-induced in-water mortality for juvenile, sub-adult, and adult hawksbills in the eastern Pacific, and is of grave concern to the population. Based on our findings, we discuss neritic habitat use by hawksbills during their 'lost years' and offer recommendations for bycatch reduction strategies, including community-based efforts to enhance sustainable self-governance via the establishment of locally crafted conservationist norms and marine protected areas at important developmental habitat.

Distribution, size range and growth rates of hawksbill turtles at a major foraging ground in the eastern Pacific Ocean

“…However, CNP is an archipelago composed of 39 small islands and multiple beaches that are conducive to hawksbill nesting. We therefore recommend a full survey of potential nesting beaches during the putative nesting season (June/July; Gaos et al, 2017). The diverse range of marine and coastal habitats present at Coiba Islands include coral reefs, seagrasses and several mangrove estuaries (ANAM, 2009).…”

“…However, recent research suggests hawksbills in the eastern Pacific may lack pelagic phase during early posthatchling development (Liles et al, 2017;Gaos et al, 2017). Our research suggests that the Coiba archipelago is a recruitment site for young juvenile hawksbills, whether they originate from pelagic or other neritic ocean systems, as the smallest turtle tagged during this study was 30.0 cm CCL Growth rate data for hawksbill turtles between 1980 and 2013 from the West Atlantic indicated a mean annual growth rate of 3.1 ± 2.3 cm year -1 .…”

“…As a result, comprehensive information on hawksbill demographics from foraging grounds in the eastern Pacific remains extremely limited. Considering the vast resources that have been invested in conservation at nesting beaches over the last decades (Gaos et al, 2017), structured on-going surveys at foraging grounds Surveys carried out in 2011 to evaluate sea turtle presence around Coiba Island identified the area as an important nesting and foraging site for several species (Ruiz & Rodriguez, 2011), but species-specific quantifications remained unavailable. Based on these findings and the presence of the pristine coral reefs in the CNP, which represent a primary hawksbill foraging habitat (Meylan, 1988;Van Houtan et al, 2016), a three-day rapid in-water assessment was carried out in September 2014 to evaluate the presence of hawksbill turtles.…”

Engaging Fishers' Ecological Knowledge for Endangered Species Conservation: Four Advantages to Emphasizing Voice in Participatory Action Research

“…For example, many conservation issues involve competition for scarce resources between an endangered species and subsistence/traditional harvesters (e.g., Bulbeck and Bowdler, 2008;Rioux et al, 2012;Liles et al, 2015a), and human-generated pollution that harms wildlife and human health (Venter et al, 2006;Vegter et al, 2014;Schuyler et al, 2015;Wedemeyer-Strombel et al, 2015). Other challenging human-wildlife interactions include fisheries bycatch (Lewison et al, 2014;Liles et al, 2017), and illegal harvest and/or hunting (Brashares et al, 2004;Von Essen et al, 2016;Silvy et al, 2018). In the European Union and United States, government regulatory agencies responsible for evaluation and enforcement of laws protecting at-risk species and ecosystems are required to allow public input, but often do so with reluctance as the process becomes complicated and additional conflict surfaces when trying to reach common ground (Peterson and Horton, 1995;Clarke and Peterson, 2015).…”

Filling the gaps in sea turtle research and conservation in the region where it began: Latin America

“…Llamas et al (2017) The third group of studies focused on several of the long-standing anthropogenic threats facing sea turtle: incidental catch (also known as bycatch) and illegal take (Wallace et al, 2011). Liles et al (2017) investigated the impact of the lobster gillnet fishery in Central America and estimated one of the highest rates of gillnet bycatch and mortality for hawksbill turtles anywhere in the world. Likewise, Pingo et al (2017) found high rates of bycatch of green sea turtles in gillnet fishery operations in northern Peru, with entanglements occurring in almost every observed fishing set.…”