Saving the Olive Ridley sea turtle

The IUCN Red List of threatened species lists the Olive Ridley Sea Turtle as vulnerable with a decreasing population (Click Here).  Our family visited Ostional for a week of service during the 2016 arribada .

The Task

During the nesting period the rangers have their hands full. Poachers want to harvest the eggs, tourists interfere with nesting turtles, and there is much data to gather to evaluate the species. After attending an informational talk at the Ostional Wildlife Refuge Ranger Station, we signed up for shifts that lasted for four hours. During this time we:

  • Cleared the beach from obstacles that would prevent the turtles from nesting.
  • Counted turtles arrivals and exits and whether or not they nested.
  • Count the number of poached nests and determine if it was people or animals.
  • Determine the zone of the nest (by markers on the beach and how close or far from the water line).
  • Counted the eggs being laid by the turtle.
  • Measured the turtle’s shell (length and width).
  • Measured the depth of the nest.
  • Measured their flippers.
  • Timed how long it took the turtle to lay their eggs.
  • Tagged the turtle.

We did shifts for each of the four days of our visit.  We took two morning shifts, and night shift and a day shift.  I volunteered for an extra graveyard shift, that was too late for the children.

The Turtles

We’ve seen turtles before, but we were not prepared for miracles that unfolded before us.  Turtles labored up the beach and picked a spot either near the dunes, in the mid section of the beach, or just beyond the waterline.  Researchers told us that turtles who laid eggs in the mid section the year before would lay eggs near the dunes in different years and vice versa.  They dug with their hind flippers. They first pushed sand out of the way, and then dug, using their flipper to scoop sand out.  Where did they learn this behavior?  They are solitary creatures who leave the nest without any parenting.  They never use or observe this skill in their daily lives, so how did they develop it?  When they find it is deep enough (again, how do they know?), they start laying.  Each clutch varies from 40 to 90 eggs.   While they were in a laying trance, volunteers measured the shell and counted eggs.  We did this with a reddened light so as to not disturb the turtle.  When the turtles finished, a lead volunteer tagged the turtle.  The turtle covered the nest with sand.   We watched in amazement as the turtles struggle back to the surf.  As things got busy, sometimes our group monitored three turtles simultaneously.   During the slower moments on the late shifts we could look down the beach and see groups of volunteers and poachers.   It moments when walking up and down the beach, we encountered several poachers, but because we were volunteers, we were instructed not to interact with them.

The turtle took time to lay their eggs.  In passing the time we’d listened to the labored breathing of these ancient animals while looking at the Milky Way: a rare communion.

The first few days we counted 6-15 turtles a day.  However, on our last day the arribada happened and hundreds of turtles came ashore.  Later comers stayed until mid-morning.  It was truly a sight to behold.

People and Nature

The Olive Ridley Turtle has a hard enough time.  Only 1 in 1000 make it to adulthood (Life cycle click here).  However, humans made it worse, by the 1980s harvesting and poaching turtles eggs were driving the sea turtles to the brink.  Consequently the Costa Rican government established the wildlife refuge in 1982 and hired rangers to patrol the beach.  With high demand for the turtle eggs and a need to salvage one of the last Mesoamerican rookeries a seemingly Faustian bargain was struck: In 1987 it was agreed to allow the harvest on the first day of each arribada, and leave the rest to develop.  With cooperation from the locals, the population of turtles is making a slow and steady comeback. (Article and data here)1.  There often is a path forward that is not a zero-sum game, but one in which everyone can benefit.  It is a matter of education, political will, and compromise.

1 “Olive Ridley Mass Nesting Ecology and Egg Harvest at Ostional Beach, Costa Rica” by ROLDAN A. VALVERDE et al. Chelonian Conservation and Biology, 2012, 11(1): 1–11g 2012 Chelonian Research Foundation

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