Living on the Edge: Hawksbill turtle nesting and conservation along the Eastern Pacific Rim

Abstract

ABSTRACT. Prior to 2007, efforts to monitor and conserve hawksbill turtles (Eretmochelys imbricata) in the eastern Pacific Ocean were opportunistic and records were virtually non-existent. The first abundance estimates were published in 2010, but contained limited data on the species. Ongoing research since that time has led to the identification of several rookeries, including sites containing large proportions of the overall hawksbill nesting currently known to occur in the region. Monitoring projects were established at several sites and have since provided substantial nesting data on the species. Here we summarize data collected between 1983 and March 2016 from all sites (n = 9) confirmed to host >10 nests in any given season to provide an update on hawksbill nesting in the eastern Pacific. We documented a total of 3,508 hawksbill nests, 265,024 hatchlings and 528 individual nesting females in the region. The vast majority of these records (99.4%, 99.9% and 99.6%, respectively) were generated subsequent to 2007, coinciding with the discovery of eight of the nine rookeries included in this study and the organization of monitoring efforts at those sites, which led to the increased documentation conferred here. Our findings should not be misconstrued as increases in actual nesting or signs of recovery, which could diminish the ongoing need for conservation actions, but rather as optimism, that there is still an opportunity to restore the species in the eastern Pacific. The top three sites in terms of average annual number of nests were Estero Padre Ramos (Nicaragua; 213.2 ± 47.6 nests), Bahia de Jiquilisco (El Salvador; 168.5 ± 46.7 nests) and Aserradores (Nicaragua; 100.0 ± 24.0 nests), and all three sites are located in mangrove estuaries in Central America, highlighting the importance of these rookeries/habitats for the survival and recovery of hawksbills in the region. The remaining six sites received between 6.9 ± 7.3 nests (Costa Careyes, Mexico) and 59.3 ± 17.7 nests (Los Cobanos, El Salvador) annually. By integrating data collected on nesting hawksbills with local conservation realities at the most important known hawksbill rookeries in the eastern 572 2 Latin American Journal of Aquatic Research Pacific, we provide a more holistic view of the conservation status and management needs of the species in this ocean region.

Potential limitations of behavioral plasticity and the role of egg relocation in climate change mitigation for a thermally sensitive endangered species

“…We recorded 2,154 nesting events from a minimum of 366 individual hawksbills, representing 72.8% of total nests recorded in the eastern Pacific during 2010–2015 and 69.3% of total mature females identified in the entire eastern Pacific region (Gaos et al, ). Of these nests, 877 (40.7%) were located at Bahía de Jiquilisco (2011–2015) and 1,277 (59.3%) at Estero Padre Ramos (2010–2015).…”

“…Hawksbill clutches incubated in beaches within mangrove estuaries at Bahía de Jiquilisco and Estero Padre Ramos had relatively low hatching success (56.8%) across all protection strategies compared to hawksbill nesting on open‐coast beaches in the eastern Pacific (e.g., 64.5%, Gaos et al, ), Caribbean (e.g., 91.6%, Bjorndal, Carr, Meylan, & Mortimer, ; 84.5%, Horrocks & Scott, ; 78.6%, Ditmer & Stapleton, ), and Indo‐Pacific (90.1% [emergence success], Limpus, ; 79.9% [emergence success], Loop et al, ; 82.4%, Dobbs, Miller, Limpus, & Landry, ; 85.2%, Hoenner et al, ). We suspect differences in overall hatching success reflect distinct biophysical conditions of beaches in mangrove estuaries, such as presence of extremely fine‐grained sand.…”

“…Hawksbill nesting occurs primarily during the rainy season between May and September, with a peak in June and July. Contrary to typical contiguous open‐coast beaches used by nesting hawksbills in other oceanic regions (Loop, Miller, & Limpus, ; Mrosovsky, ), hawksbills at these two sites nest on low‐relief beaches scattered within mangrove estuaries (Gaos et al, ; Liles, Peterson, Seminoff, et al, ).…”

“…Critically endangered hawksbill turtles ( Eretmochelys imbricata ) in the eastern Pacific Ocean belong to one of the least resilient (Fuentes, Pike, Dimatteo, & Wallace, ) and most threatened marine turtle regional management units (RMU) in the world (Wallace et al, ), with fewer than 700 adult females nesting along 15,000 km of Latin American coastline (Gaos et al, ). Further, >70% of this nesting activity is concentrated on low‐relief beaches in mangrove estuaries at Bahía de Jiquilisco in El Salvador and Estero Padre Ramos in Nicaragua (Gaos et al, ; Liles, Peterson, Seminoff, et al, )—ecosystems that are particularly vulnerable to increasing global temperatures and sea‐level rise (Gilman, Ellison, Duke, & Field, ).…”

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

“…Two studies addressed important information gaps of nesting abundance from unreported and understudied beaches. Gaos et al (2017) analyzed 33 years of nesting records for the hawksbill turtle from nine Preface 503 sites along the eastern Pacific. They reported a larger number of deposited nests, contrasting with previous estimates that were based upon more limited information (Gaos et al, 2010).…”