Among Sea Turtles
Parismina, a small village in Costa Rica between the Reventazón River and the Caribbean Sea, is only accessible by boat or plane. Three species of turtle – leatherback, hawksbill and green – lay their eggs on the beach there. Marine turtle populations are in decline worldwide and Parismina doesn’t buck the trend. In 2001 a group of teenagers, alarmed by the rise in poaching, joined forces with the coast guard to patrol the beach and went on to found the Asociación Salvemos las Tortugas de Parismina, a non-profit conservation project.
ASTOP relies on money brought in by volunteers to keep going but is managed by local people, who decide the shape of the programme and how to make the best use of volunteers. It also provides employment for former poachers. They make the best spotters, as they know where and when the turtles are most likely to come out on the beach to lay their eggs. Before ASTOP was founded, 98 per cent of green turtles were killed for their meat and 98 per cent of all three species’ nests were poached on Parismina beach. It’s now down to 38 per cent. As well as saving 10,000 newborn turtles a year, ASTOP supports approximately one third of the village.
I volunteered with ASTOP last summer. We carried out beach patrols every night from 8 p.m. to 4 a.m., in two four-hour shifts. We would walk up and down the beach, looking out for turtles. We weren’t allowed torches, which would scare or confuse the animals. Once I was lucky enough to come across two green turtles hatching, but most nights there was torrential rain and we didn’t spot any turtles or tracks. Tracks usually meant either that the turtle had laid her eggs and returned to the ocean, or was in the process of laying or returning. Once, however, we came across tracks that guided us to the turtle’s last position up the beach: there no eggs or returning tracks. Instead, there were the clear tracks of a turtle being dragged away. A poacher must have stolen it along with its eggs.
On better nights, we were lucky to witness turtles laying their eggs by digging in the sand. The eggs need to be buried at a certain depth. The temperature of the sand where they are incubated determines the turtles’ sex. Females need warmer temperatures to develop – around 31ºC – while males require around 28ºC. Ideally the sand is between these two temperatures so plenty of turtles of both sexes develop. If climate change leads to average temperatures increasing too much, the eggs may not hatch, or too many females may develop and not enough males. Rising sea levels will affect the beaches where turtles lay their eggs. Already in Parismina they have less nesting space than they used to.
Once the turtles finished laying their eggs (around 120 each on average, although the hawksbill can lay more than 200), some volunteers stayed to make sure the mothers made it safely back into the ocean, while others collected the eggs and brought them back to the hatchery, where we reburied them in the sand. The hatchery was monitored 24 hours a day to keep away poachers, dogs and chickens. Monitoring the hatchery was probably the easiest job I had: mostly it meant lying in a hammock.
Only one in a thousand turtles make it to full adulthood after hatching. They are extremely vulnerable in the ocean to predators. An adult leatherback can be three metres long; when they hatch they’re 15 cm. Turtles are also threatened by plastic waste, which resembles their favourite prey, jellyfish. Ingested plastic can block their digestive tracts, preventing them from eating. Once a week we spent several hours collecting all the rubbish washed up on the beach and separating it into different bags. Most of it was plastic but there was also glass and electronics.
One day I saw around eighty newborn leatherbacks making their slow way from the hatchery down to the ocean. I asked one of the locals why we couldn’t pick them up and carry them to the water. He said they need to get to know the sand and the beach because the female turtles that make it to adulthood, after swimming thousands of miles across the oceans, will return to the same beach and lay their eggs, at the same spot they were born thirty years earlier.
ISSN 0260-9592 Copyright © LRB Limited 2017