'Arribada' vanishes from shores

The rare and awe-inspiring natural event known as arribada-a synchronized mass nesting of Olive Ridley sea turtles-has vanished from Pakistani shores, experts say. Once a common sight along the country's coastline, this unique species has not been recorded nesting in Pakistan since 2001.

Arribada, a Spanish word, meaning 'arrival', refers to a remarkable phenomenon where thousands of female Olive Ridley turtles come ashore to lay eggs. This event occurs at select beaches across the Pacific, Atlantic, and Indian Oceans, and is considered one of nature's most spectacular events.

According to marine experts, five of the seven known species of sea turtles used to frequent Pakistani waters until the 1970s. However, in the following decades, only two species-the Green Turtle and the Olive Ridley-continued visiting the region. Now, only Green Turtles remain.

Olive Ridley turtles, the smallest and most abundant species of sea turtles globally, are known for their olive-green shells and preference for warm tropical waters. Despite their adaptability, they have mysteriously disappeared from Pakistani beaches over the past two decades.

Experts believe both environmental and human-induced factors may be responsible for their disappearance.

According to Moazzam Khan, Technical Advisor to WWF Pakistan, climate change could be a significant contributor to the disappearance of Olive Ridleys from the country's coastline.

However, Dr. Babar Hussain, Natural Resource Management Coordinator at IUCN Pakistan, points to a more immediate cause-the Tasman Spirit oil spill that occurred off the coast of Karachi in 2003. "This incident had a devastating impact on marine biodiversity," he said. "Since the spill, no Olive Ridley turtles have been sighted along our shores."

Globally, Olive Ridley turtles are known for their synchronized nesting behaviour. During arribada, hundreds of female turtles come ashore in moonlit hours to dig nests in the sand, each laying between 100 and 120 eggs. Once the eggs are laid and buried, the females return to the sea. After 45 to 60 days, hatchlings emerge and instinctively crawl toward the ocean.

These mass nesting events are observed in countries like Mexico, Costa Rica, and India. For instance, La Escobilla beach in Mexico hosts up to 450,000 nests annually, while Costa Rica's beaches receive nearly 600,000 female turtles during the breeding season. In India, Odisha's Gahirmatha and Rushikulya beaches are world-famous arribada sites.

Despite confirmed Olive Ridley migration routes near Pakistan, the country has not seen a nesting event in over two decades. Experts stress that this ecological loss is not just a scientific concern but also a missed opportunity for promoting eco-tourism. "The arribada is not only a spectacle of nature's coordination but also a reminder of how delicately balanced marine ecosystems are," said Moazzam Khan.