By Kathryn Cawdrey
OSTIONAL, Costa Rica — Just before sunrise on Dec. 30, sirens broke the still, morning air in the remote town of Ostional, Costa Rica. A man with a bullhorn patrolled the main, gravel street yelling, “Arribada, Arribada!”
An arribada is the mass nesting of sea turtles, in this case the olive ridley. This species of sea turtle only nests at eight beaches in the Western Hemisphere, said Yenifer Ruiz Coba, leader of guides for the Integral Development Association of Ostional, locally known as ADIO.
At 5:30 a.m., Ostional residents sped to the beach, where more than 8,000 olive ridleys were surfacing to lay eggs in the sand.
Arribadas occur as often as once a month throughout the year, though the number of turtles that arrive changes according to season. During the rainy season, which is from May to November, more than 100,000 turtles may nest in a single day. The dry season can attract 8,000 to 10,000.
After 45 to 55 days, the hatchlings emerge and make their way to the sea. In an average year, up to one million turtles hatch and make it into the ocean. But some years, there are up to three million. Though one million sounds overwhelming, it’s only a fraction of the eggs left on the beach. Many face predation before and after hatching by fish, birds, crocodiles and even stray dogs.
Ruiz explained that only 1 out of 100 new hatchlings will make it to adulthood. Therefore, only 7 percent of eggs laid will be successful. Reasons eggs don’t hatch include predation, a nest that is too dense, destruction of nests by other females, contamination of the beach due to fungi or bacteria, and poaching.
The association and residents of Ostional implemented a program 29 years ago that would make use of the unsuccessful eggs. By regulating egg harvesting, the association can reduce illegal poaching, profit from egg removal and conserve olive ridley turtles.
This program reduces illegal poaching by creating a legal market for the sale of turtle eggs, the only one of its kind, local officials said. Egg buyers who seek to sell the eggs for consumption have to fill out paperwork and keep the transaction receipt. If a seller has eggs not approved as Ostional eggs, they face legal action: jail time, large fines or community service. The residents of Ostional also receive 200 eggs per family, free of charge.
The money received from turtle egg sales is given back to harvesters and the association. About 70 percent goes to the harvesters, who all receive equal pay regardless of status. The remaining 30 percent goes to the association for upkeep of buildings, utilities, payment for guards or other necessities, Ruiz said.
The association also harvests eggs to encourage survival of nests. Because of the nesting en masse, female turtles arriving later in the arribada destroy 60 percent of nests that have already been made, Ruiz said. The association only harvests during the first three days of an arribada. Additionally, if the nests are too close together, there is not enough oxygen for them all to survive.
Tomás Chavarria, 71, has lived in Ostional for 50 years and was member of the local police force for 29 years. Chavarria believes the turtles and their conservation go hand-in-hand to achieve sustainability, for both the community and the turtle.
“We are living from what we get from nature, but also giving back,” he said.
Edited by Amanda Henderson