Pacuare Reserve, on the Caribbean coast of Costa Rica, has been protecting sea turtles since 1989. These animals are among the most difficult species to monitor and protect, as they spend more than 90% of their lives in the ocean, so most of the practices used to assess species trends are implemented on nesting beaches.
The Reserve protects four different species of sea turtles and receives hundreds of students, volunteers, and visitors each year who help collect data to assess the conservation status of each species, primarily the leatherback sea turtle (Dermochelys coriacea), whose North Atlantic subpopulation is endangered (IUCN, 2019).
Leatherback sea turtle (Dermochelys coriacea)
The main focus of the Sea Turtle Conservation and Research Program at Pacuare Reserve is the monitoring and protection of the world's second largest nesting population of leatherback turtles along 3.7 miles of beach. The nesting season extends from February to August, peaking between April and May. Pacuare Reserve receives an average of 548 leatherback nests per year, making it the fifth most important nesting beach for this species worldwide.
This is a comprehensive program, as it collects biometric data on nesting female turtles, protects the nests by relocating them, and educates national and international student groups on conservation.
Nest hatching success has been analyzed as an indicator of effective nest management decisions. Since 1994, different treatments have been used for nest conservation: in situ nests are left at the site where the turtle decided to nest; nests are relocated along the beach to points where beach erosion is not a problem; and nests are moved to hatcheries (as of 2018). During the 2022 season, the in situ nests had only a 16% hatching success rate of hatchling turtles, compared to 78% reported in the hatcheries.
The presence of security guards and nightly censuses by research assistants, students, volunteers and visitors has reduced illegal nest harvesting from 98% of nests (in 1989) to only 0.7% (in 2022). Currently, more than 23,000 females have been tagged, more than 1.8 million eggs have been saved, and more than 750,000 baby turtles have been released to the sea.
Sea turtle night census
In addition to monitoring leatherback nesting, we also protect the critically endangered hawksbill sea turtle (Eretmochelys imbricata) and the endangered green sea turtle (Chelonia mydas). Some loggerhead sea turtle (Caretta caretta) nests have also been recorded less frequently.
From February 15 to October 31 of each year, night censuses are conducted to monitor nesting. At least three censuses are conducted each night by two research assistants (or one assistant accompanied by students). The censuses last 4 to 6 hours per shift, which depends directly on the number of nesting females on the beach.
Each sea turtle found during the census is identified with two metal tags on its hind flippers (on the uropigeal membrane) and a microchip on the right shoulder. “Events” are classified as nests or false exits (if a nesting attempt is observed that was not successfully concluded). Morning censuses are also conducted, one at each station in The Reserve (north and south), to monitor both beach sections starting at 5:00 AM to record any new nesting activity and mark the GPS points of the original nest locations.
Egg relocation is a method often used to improve the reproductive success of threatened reptile populations by physically moving nests to an area where they are more likely to hatch. Over the years, nest relocation has been a conservation strategy employed at Pacuare Reserve to protect nests from looters, rising tides, and beach erosion.
All eggs are reburied in excavated holes, mimicking the natural size and shape of turtle nests. Nests placed both inside and outside the hatchery are protected with baskets lined with anti-aphid mesh to minimize fly and crab predation and to control hatchlings output. Since its implementation in 2018, no illegal harvesting has ever been recorded inside the hatchery.
Sea turtle nest hatchery
In total, 81,000 different females have been observed at Pacuare Reserve since 1989, and more than 5,000 were encountered only once during the entire observation period. In addition, approximately 21,000 leatherback nests have been reported during the same period.
The Pacuare Reserve's Sea Turtle Conservation and Research Program is an outstanding example of dedicated efforts to the protection and conservation of these endangered species. Through monitoring, nest relocation and bio-literacy efforts, a significant impact has been made on the survival of sea turtles in the region. If you would like to support the program and the Pacuare Reserve's other conservation and research programs, you can make a donation here, or contribute in other ways, as indicated here.