The Olive Ridley turtle (Lepidochelys olivacea), a weak sea turtle species, made headlines earlier this yr: a record-breaking seven lakh turtles had nested at Odisha’s Rushikulya seashore alone in March.
These turtles are famend for his or her synchronised mass nesting occasions known as arribada, a Spanish phrase meaning “arrival”. For many individuals, the Rushikulya arribada signalled hope — however for conservation biologists, it raised vital questions on the future of these weak animals and whether or not human interventions, even well-meaning ones, may change the course of nature itself.
While some localised populations of Olive Ridley turtles have expanded, the IUCN Red List has estimated that the quantity of Olive Ridleys worldwide has dropped by 30-50% since 1960. The Olive Ridleys’ major nesting websites are alongside the Pacific coasts of Mexico and Central America, though Odisha can also be a very vital location.
The State’s 480-km-long shoreline hosts three main nesting seashores: Gahirmatha, between the Brahmani and Baitarani river mouths; Devi, 100 km south of Gahirmatha; and Rushikulya, 320 km additional south.
The the place of it
Research has discovered that Olive Ridley turtles that hatch at a nesting web site are ‘imprinted’ with a map of the native magnetic discipline. Decades later they return with exceptional precision to the web site by following this map. The phenomenon is known as philopatry: a mix of reminiscence, environmental components, and the earth’s geomagnetic cues. Philopatry is bolstered by a multiplier impact: as females with sturdy philopatric tendencies improve in quantity, they reinforce web site constancy throughout generations.
There are different ecological components too. Studies on the Loggerhead sea turtles (Caretta caretta) have additionally revealed that their nesting zones are close to free swirls of chilly water in the seas — known as cold-core eddies — that transfer vitamins up from the deep sea to the floor, together with these wealthy in chlorophyll. Other components that have an effect on their selection of nesting websites embody salinity, land slope, threat of predation, and rainfall.
Nesting websites are thought of extra appropriate if extra turtles have nested there earlier than — however as turtle populations swell whereas the measurement of the most beneficial nesting grounds doesn’t, seashores typically turn out to be battlegrounds. A inhabitants that arrives after one other has already nested at a seashore would possibly dig up current nests — feminine turtles are guided by olfactory cues and feminine urine — and break the eggs. This occurred earlier this yr throughout the second mass-nesting occasion at Rushikulya.
Eggs which might be damaged and displaced appeal to predators. Experts beforehand believed predators used visible cues to detect turtle nests. More current analysis has discovered that olfactory cues, particularly the scent of disturbed soil and damaged eggs, are extra important. Thus, a species’ most profitable survival technique can also sow the seeds of its decline.
In sea turtles, temperature determines the intercourse of hatchlings. Studies of Loggerhead turtles have discovered that their populations are extra feminine after they nest on hotter seashores. Researchers are nonetheless amassing comparable knowledge pertaining to Olive Ridley turtles. With rising temperatures shifting the intercourse ratio extra in the direction of females, the multiplier impact is predicted to get bolstered as extra females return to mass-nesting seashores in the coming years.
How mass nesting begins
For their first arribadas, feminine sea turtles choose their nesting websites with none discernible sample and use them irregularly. If a feminine turtle reaches the reproductive stage of its life earlier than it is ready to attain the seashore the place it hatched, it could set up a brand new nesting web site nearer to its foraging grounds. Its hatchlings can be imprinted with this location and they’re going to try and return to it later.
Put one other approach, for a sea turtle inhabitants to thrive, it wants strays and wanderers like these turtles, which set up new locations for the arribada. If they’d been compelled to stay to at least one web site over tens of millions of years, they’d probably have turn out to be extinct as a consequence of overcrowding in the mass nesting seashores.
Modern conservation has helped increase turtle populations, particularly by artificially incubating eggs and defending seashores. The query naturally arises: may these measures be too profitable? Because if weaker people that might have perished in the wild are actually capable of survive and reproduce, the inhabitants’s genetic resilience will drop.
People, turtles, reputation
No conservation story is full with out acknowledging the position of native communities. In Odisha, fisherfolk and villagers are important allies: they guard nests, curb egg poaching, and information conservationists. But not all human interactions are benign.
Turtle tourism has surged lately. The inflow of guests creates alternatives to boost consciousness but it surely additionally stresses these light creatures. Crowds collect to observe nesting turtles at evening, utilizing shiny lights, clicking selfies, and — in some disturbing instances — scooping sand out of the floor to observe the egg-laying and even sitting on turtles for images.
Such acts disturb nesting behaviour and will have an enduring affect on the turtles’ reminiscence, discouraging them from returning to the web site.
Scientists are additionally simply starting to grasp the cognitive and emotional interior lives of turtles. It’s completely doable that what we expect of as harmlessly marvelling at them might be disrupting the historical rhythms of these mariners.
In different phrases, it’s not about numbers or rescue operations. The precedence is to make sure the longevity of these nesting seashores and to stability tourism with moral duty.
Olive Ridley turtles have endured mass extinctions, shifting continents, and rising seas. Their resilience is exceptional — however not limitless. Regardless of whether or not turtles proceed to return to nesting websites regardless of these disturbances, people’ moral duty is obvious: to safeguard the ecological stability that retains sea turtles going.
Deyatima Ghosh is an assistant professor at the Centre for Urban Ecology, Biodiversity, Evolution and Climate Change, JAIN (Deemed-to-be) University, Bengaluru.
Published – May 21, 2025 05:30 am IST
