Nesting trends of olive ridley sea turtles Lepidochelys olivacea (Testudinata: Cheloniidae) on two beaches in Northwestern Mexico after 30 and 40 years of conservation

Abstract

Introduction: Although olive ridley sea turtles (Lepidochelys olivacea) are the most abundant sea turtles in the world, quantitative information is scarce and unevenly distributed among regions. There are many management and conservation programs for this species, and assessments are necessary to identify nesting trends and effectively manage current conservation programs. PROTORMAR-UAS is a Research and Conservation program for the olive ridley turtle created by the Autonomous University of Sinaloa, Mexico. The program utilizes two biological stations: Santuario Playa Ceuta (SPC) and Playa Caimanero (PC). Objective: To evaluate the nesting trend of olive ridley turtles on two beaches in Northwestern Mexico and to predict prospective nesting trends for the next 30 years. Methods: Using annual nesting data collected over 40 years at SPC (1976-2016) and 30 years at PC (1986-2016), we evaluated nesting trends, hatching success, predation and poaching of olive ridley turtles on the two beaches in Northwestern Mexico. Then, prospective nesting estimates for the next 30 years were calculated predictive time series model. Results: A positive and significant correlation was identified between the number of annual nests and time for both beaches (rho = 0.850, P ≤ 0.01 for SPC; rho = 0.677, P ≤ 0.01 for PC); the average hatching success rates were 65.09 at SPC and 60.72 % at PC. The predictive time-series model indicated that the numbers of nests will continue to increase through 2045, increasing three-fold at SPC and six-fold at PC with respect to the last year of monitoring. Conclusions: There was a clear positive trend in the number of olive ridley sea turtle nests at both sites, which is consistent with trends found in other recent studies from the region. Therefore, we suggest that PC be designated a legally protected nesting area since it is located within the latitudinal limits of olive ridley nesting and given the need for resources for camp operation considering increased nesting and current problems with predation and poaching. Because in Mexico operating a nesting beach without any protection status implies not having a budget for its management.

Anidación de la tortuga marina Lepidochelys olivacea (Testudinata: Cheloniidae) en Campamento Tortuguero Cedeño, Honduras (2011-2021)

“…Por otro lado, la tasa de eclosión global en las tres playas fue baja con el 66.4 % en comparación a lo registrado en otros estudios (Arzola-González et al, 2019;James & Melero, 2015;Sosa-Cornejo et al, 2021;Viejobueno-Muñoz & Arauz, 2015). No obstante, del 2011 al 2021, la cantidad de neonatos liberados se incrementó en promedio en un 30 %.…”

Threats and Vulnerabilities for the Globally Distributed Olive Ridley (Lepidochelys olivacea) Sea Turtle: A Historical and Current Status Evaluation

“…However, the main arribada nesting areas are located on the Pacific coast of Mexico, in Costa Rica, and in northeast India [ 45 , 46 , 47 ]. There are also several beaches reported as olive ridley solitary nesting spots in these regions [ 25 , 48 ], as well as in the Central African Atlantic Coast [ 26 , 49 ], Australia [ 50 ], French Guiana and Brazil in the western Atlantic [ 17 , 39 ], South American Pacific [ 51 ], South and Southeast of Asia [ 52 ], and on most island groupings throughout the tropics [ 5 , 53 ].…”

“…Animals 2022, 12, x FOR PEER REVIEW 3 of 23 conservation efforts, including nesting beach protection and rules prohibiting sea turtle commerce and direct capture on land and at sea, in particularly across the Americas (e.g., Costa Rica and Mexico), have resulted in highly promising current trend statistics [25].…”

“…In oceanic waters, olive ridleys are exposed to a variety of dangers such as harmful algal blooms, climate change, bycatch, directed fishing nets capture, marine litter, and contamination, which can be fatal and a potential cause of death [ 21 , 22 , 23 , 24 ]. Assessing a species’ risk of extinction is difficult; it requires a thorough understanding of global trends spanning generations [ 25 ]. The loss changes in population size of olive ridleys drive their worldwide status.…”

“…Despite the fact that monitoring arribada sizes has proven to be difficult, local initiatives have provided solid data for status assessments. Decades of conservation efforts, including nesting beach protection and rules prohibiting sea turtle commerce and direct capture on land and at sea, in particularly across the Americas (e.g., Costa Rica and Mexico), have resulted in highly promising current trend statistics [ 25 ]. Over the last two decades, most arribada rookeries have had positive or stable trends in the Americas; nonetheless, populations across Asia are still in rapidly decline [ 5 ].…”