Odisha's allure, World’s curiosity : Olive Ridley “Arribada”

Olive Ridley “Arribada” - Nature's Grand Congregation

Odisha, the Land of Lord Jagannath. And understandably, every year, the coastal city of Puri, Odisha, transforms into a sea of humanity as millions of devotees converge to witness the grand world famous spectacle, the Puri Rath Yatra. This grand festival centers on the procession of Lord Jagannath, along with his siblings Lord Balabhadra and Goddess Subhadra, as they journey from the Jagannath Temple to the Gundicha Temple.

Similarly, the Odisha coast also witnesses one of the planet's most remarkable natural phenomena: the annual mass nesting, or "arribada," of Olive Ridley sea turtles. This spectacle, particularly at sites like the Rushikulya river mouth and Gahirmatha beach, represents the largest known gathering of these vulnerable marine reptiles. In 2025, the Rushikulya rookery saw record breaking numbers. Reports indicate that numbers reached over 8.9 lakh turtles at Rushikulya beach, exceeding previous records.

“Arribada”, the "arrival"

The word "Arribada" originates from the Spanish "arribar," meaning "to arrive”. "Arribada" in Spanish, meaning "arrival," is specifically refers to a remarkable natural phenomenon: the mass, synchronized nesting of sea turtles. Primarily, this term is associated with olive ridley and Kemp's ridley sea turtles.  

During an Olive Ridley “Arribada”, thousands of female sea turtles gather offshore and then come ashore simultaneously to lay their eggs on a beach. This mass nesting event creates an incredible spectacle, with vast numbers of turtles covering the beaches. Arribadas are a crucial part of the life cycle of these sea turtle species. These events are essential for the survival of the species, as the sheer number of eggs laid can overwhelm predators, increasing the chances of hatchlings surviving.

Early Observations and Discovery (1970s):

While local communities were likely aware of the mass nesting events, the scientific community's attention was drawn to this phenomenon in the 1970s. In 1974, Robert Bustard, an FAO consultant, documented the mass nesting of Olive Ridley turtles at Gahirmatha beach while conducting a crocodile survey in Bhitarkanika. This marked the official recognition of this unique event by researchers.

In this context, it's crucial to acknowledge the underappreciated contributions of Dr. Lala Aswini Kumar Singh, a Research Officer with the Odisha Forest Department. While Robert Bustard is widely credited with the initial observations of Olive Ridley turtle mass nesting, Dr. Singh's tireless and dedicated work in that area also deserves far greater recognition.

Further Discoveries and Research (1980 onwards):

Following the initial discovery, further research and exploration led to the identification of more mass nesting sites along the Odisha coast. In 1981, a second mass nesting site was discovered at the mouth of the Devi River. In 1994, a third mass nesting site was identified at the Rushikulya river mouth. These discoveries highlighted the significance of the Odisha coast as a crucial nesting ground for Olive Ridley turtles.

A Zoological Survey Of India (ZSI)-Pune study, published in leading scientific journal Marine Pollution Bulletin by Elsevier, has analysed shoreline changes from 1990 to 2022 and found the world-famous Olive Ridley turtle nesting ground at Gahirmatha Marine Wildlife Sanctuary in Odisha has shifted northwards over the last three decades owing to severe coastal erosion caused by climate change and human activities. Dr Basudev Tripathy, Scientist, ZSI-Pune, described the findings as a matter of concern for the future of Olive Ridley Arribada as rampant erosion has drastically reshaped the coastline, forcing the turtles to shift their nesting ground northwards by 14km, from the mainland to an adjacent island, after which there is no space.

Arribada: 2025 Sets New High

In 2025, Odisha's coast witnessed an extraordinary arribada of Olive Ridley turtles, shattering all prior records. The sheer scale of the mass nesting event was unprecedented, with a record-breaking 6.99 lakh Olive Ridley turtles arriving at Rushikulya Beach in Odisha during 16th to 23rd February’2025, surpassing the previous record of 6.37 lakh in 2023.

In addition, encouraging news comes with the Olive Ridley turtles once again returning to the Gahirmatha area on the mainland. After nearly three decades, a large-scale Arribada has been observed on the Gahirmatha Marine Reserve Forest, with an estimated of 5 lakh turtles coming ashore for nesting this year covering Ekakulanasi, Agaranashi-2, Satabhya, Pentha Beaches.

Joy and Worry: Rare Second Nesting Event at Rushikulya

In 2025, the Rushikulya rookery in Odisha experienced an unusual and significant event for Olive Ridley turtle conservation. Following a major mass nesting (arribada) from February 16th to 23rd, a second wave of turtles arrived to lay eggs starting on March 21st and continuing for several days. This is noteworthy as it occurred despite unfavorable weather conditions, including cloudy skies and rain. Reports indicate that over 2 lakh Olive Ridley turtles have come ashore on Rushikulya beach for this rare occurrence. With this the number of turtles coming to Rushikulya Beach reached a record height of around 9 lakhs this year. While this brings joy, it also presents a challenge for forest authorities and local volunteers who are working to protect the eggs, as the second arribada increases the risk of damaging the eggs from the first nesting phase, which are nearing their hatching stage. Nevertheless, this second event emphasizes the critical importance of Rushikulya beach as a vital nesting site for Olive Ridley turtles and highlights the ongoing need for conservation efforts.

Odisha's Olive Ridleys: Unique Genetic Lineage 

New findings from a joint investigation by the Wildlife Institute of India and the Centre for Cellular and Molecular Biology indicate that Olive Ridley turtles nesting on Odisha's Rushikulya beach possess a distinct genetic makeup, setting them apart from global populations, including those in Sri Lanka. This research, which involved analyzing sea turtle genetics across India's mainland and islands, points to the existence of a unique Indian Olive Ridley population. The study also posits that these Indian Olive Ridleys, along with Kemp's Ridley turtles, may be the surviving lineages of a once widespread global population that declined due to climate changes linked to the formation of the Isthmus of Panama.

Further, the emerging understanding of the migratory habits of these exotic species pave the way for significant future research. A striking example is the over 3,500 kms migration of a turtle. Identified by flipper tag "03233," this turtle was tagged on March 18, 2021, at the Gahirmatha nesting site in Odisha by Dr. Basudev Tripathy and was subsequently found nesting at Guhagar beach in Maharashtra on January 27, 2025. This observation potentially represents the first documented instance of a turtle nesting on both the eastern and western coasts of India, raising intriguing questions about inter-coastal movements.

A Close Look: The Stages of “Arribada”

This incredible phenomenon involves different stages spread over few months starting with Pre-nesting aggregation in sea to journey of hatchlings back to sea. Thankfully, I could witness all these stages from close quarters and understood the intricacies. The various stages of Olive Ridley turtle arribada are as under:          

1. Pre-Nesting Aggregation: Before the arribada, large numbers of female turtles gather in the waters just offshore from the nesting beach. This aggregation period can last for several days or even weeks, and scientists are still trying to fully understand what triggers this behavior. Factors like lunar cycles, weather patterns, and pheromones may play a role in signaling the turtles to come ashore.

2. The Emergence: Once the conditions are right, the turtles begin to emerge from the sea, usually at night. They crawl ashore in waves, often in incredibly high densities, covering the beach. This mass emergence is a spectacular sight, with thousands of turtles moving across the sand.  

3. Nest Site Selection and Preparation: Each female turtle selects a spot on the beach to dig her nest. She uses her flippers to excavate a hole in the sand, typically about 40-50 cm deep. This process can take some time, and the turtle may make several attempts before finding the perfect location.

Digging of nest

4. Egg Laying: Once the nest is ready, the turtle begins to lay her eggs. She deposits a clutch of around 100-150 eggs, which are round and leathery. The egg-laying process can take about an hour.

5. Nest Covering and Camouflage: After laying her eggs, the turtle carefully covers the nest with sand, using her flippers to pack it down firmly. She then camouflages the nest by scattering sand and debris around it, making it difficult for predators to find.

Packing of nests

Camouflaging the nest

6. Return to the Sea: Once the nest is secure, the female turtle makes her way back to the sea. She may be exhausted after the nesting process, but she instinctively returns to the ocean to feed and prepare for the next nesting season.

7. Incubation: The eggs incubate in the warm sand for about 45-60 days. During this time, the sun's heat warms the eggs, and the embryos develop into hatchlings.

8. Hatching and Emergence: The hatchlings emerge from the nest at night, usually all at once. They instinctively head towards the brightest horizon, which is typically the sea. This is a critical stage, as the hatchlings are vulnerable to predators both on land and in the water.

9. The Journey to the Sea: The hatchlings make their way across the beach and into the ocean.   They begin their journey into the sea, where they will spend the next few years growing and maturing.

The Perfect Habitat: Why Olive Ridleys Choose Odisha

Odisha's coast is particularly suitable for Olive Ridley turtle mass nesting due to a combination of factors:   

· Sandy Beaches: Olive Ridleys prefer to nest on beaches with fine to medium grain sand. Odisha has long stretches of such beaches, particularly at Gahirmatha, Devi River mouth, and Rushikulya, which are major nesting sites.   

· Sheltered Coastline: The coast of Odisha offers a degree of shelter from strong waves and predators, providing a relatively safe environment for nesting.

· Food Availability: The waters off the coast of Odisha are rich in food sources for Olive Ridleys, such as crustaceans, mollusks, and fish. This abundance of food attracts the turtles to the area.   

·  Suitable Climate: The tropical climate of Odisha provides warm temperatures necessary for the incubation of turtle eggs.

· Conservation Efforts: The Odisha government and various NGOs have implemented strong conservation measures to protect Olive Ridley turtles and their nesting sites. These efforts include beach patrols, nest protection, and awareness campaigns.  

· Historical Nesting Sites: Olive Ridleys exhibit a strong tendency to return to the same beaches where they were born to nest. Odisha has been a nesting ground for these turtles for centuries, creating a strong instinct for them to return.   

Threats to Olive Ridley Turtle Arribadas

It's important to note that while Odisha offers ideal conditions for Olive Ridley nesting, these turtles still face numerous threats and the damage or loss of eggs at their mass nesting sites in Odisha is a significant concern. Here are the primary reasons for this:

1. Predation:

• Natural Predators: Various animals prey on Olive Ridley eggs, including wild dogs, jackals, pigs, birds (like crows and eagles), and monitor lizards. These predators can dig up nests and consume the eggs.

2. Habitat Loss and Degradation:

• Coastal Development: Construction of ports, roads, and other infrastructure in coastal areas can destroy nesting beaches and disrupt nesting activities.

• Beach Erosion: Natural erosion and human activities can lead to the loss of nesting beaches, making it difficult for turtles to lay their eggs.

• Pollution: Pollution from industrial and agricultural runoff can contaminate nesting sites and harm eggs. Light pollution from nearby development can also disorient hatchlings, leading them away from the sea.

3. Human Activities:

• Fishing: Olive Ridley turtles often get entangled in fishing nets, leading to injuries or death. This can also prevent females from reaching nesting beaches to lay eggs.

• Egg Collection: In some areas, eggs are collected for consumption or sale, despite being illegal. This directly reduces the number of hatchlings.

• Tourism and Disturbance: Increased tourism and human presence on nesting beaches can disturb nesting females and lead to stress, reducing nesting success.

4. Natural Factors:

• Overlapping Nests: During arribada, thousands of females come ashore to lay eggs simultaneously on the same beach. This high density of nesting turtles often lead to nests being dug close together, resulting in overlapping and potential damage to eggs. This is one of the major reasons for damage to turtle eggs.

  Egg damage due to overlapping nesting

• Extreme Weather: Cyclones, storms, and floods can wash away nests or bury them under sand, preventing eggs from hatching.

• Temperature: Extreme temperatures can affect the incubation of eggs and the sex ratio of hatchlings.

5. Other Threats:

• Disease: Diseases can affect turtle populations and egg viability.

• Boat Strikes: Turtles can be injured or killed by collisions with boats.

Conservation Efforts:

The Odisha government and various organizations are working to protect Olive Ridley turtles and their nesting sites. These efforts include:

• Protecting nesting beaches: Establishing protected areas and restricting development in these areas.

• Combating poaching: Enforcing laws against egg collection and illegal fishing.

• Raising awareness: Educating local communities and the public about the importance of turtle conservation.

• Monitoring populations: Tracking turtle populations and nesting success to assess conservation efforts.

Multifaceted Targeted Conservation Initiatives

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·  “Operation Olivia" : a dedicated initiative of the Indian Coast Guard 

"Operation Olivia", a crucial conservation effort undertaken by the Indian Coast Guard along the Odisha coast, is an annual initiative dedicated to safeguarding the vulnerable Olive Ridley sea turtles during their nesting season. From November to May, the Coast Guard deploys vessels and aircraft to patrol the coastal waters, particularly around the Gahirmatha Marine Sanctuary and Rushikulya rookery. This operation is crucial in preventing illegal trawling, which poses a significant threat to the turtles, ensuring their safe passage to nesting sites and protecting them from entanglement in fishing nets. By maintaining constant vigilance, "Operation Olivia" plays a vital role in the conservation of these endangered marine creatures.

· The annual 60-days fishing ban along the Odisha coast 

As a significant conservation move, the Odisha government imposes a 60-day fishing ban starting April 15, continuing through June 14 every year. This annual measure, which prohibits fishing activities for all motorized boats and trawlers, aims to protect marine biodiversity and support fish breeding during the critical spawning season. This period also coincides with the turtle eggs hatching season.

· Community-Driven Conservation of Olive Ridleys

The remarkable mass nesting of Olive Ridley turtles in Odisha is a testament to the power of collaborative conservation. Crucial to the success of protecting these vulnerable creatures are the dedicated efforts of local communities and volunteers. Their involvement is indispensable, from patrolling beaches to safeguarding nesting sites and assisting with the safe release of hatchlings. This grassroots participation fosters a deep sense of ownership and responsibility, ensuring the long-term survival of the Olive Ridley turtles along Odisha's coast. Their local knowledge, combined with the passionate support of volunteers, creates a formidable force in preserving this natural wonder.

·  Decoding Olive Ridley Migration: Satellite Tracking Resumes After 15 Years

On March 12-13, 2025 two female turtles at Gahirmatha Marine Sanctuary in the Kendrapara district were tagged with advanced transmitters, reigniting efforts to decode the species’ elusive migration patterns and bolster global conservation strategies using advanced satellite tracking technology. This landmark initiative, reinitiated by the Odisha Forest Department, in collaboration with the Wildlife Institute of India (WII) after a 15-year hiatus, is a landmark step towards marine conservation of this endangered Olive Ridley turtles.

A Beacon of Hope: Youth Protecting Endangered Turtles at Arribada

Throughout my observations of the Arribada 2025, I was deeply impressed by the dedication and remarkable contributions of a youth group from the Sattvic Soul Foundation. Operating in the vulnerable buffer zone of New Podampeta beach facing frequent human interference outside the protected area, they tirelessly work to safeguard these endangered turtles. Led by Shri Satyabrata Samal, their efforts include proactive pre-nesting beach cleanups, removing debris like fishing nets and plastics, and protecting hatchlings from predators and safely leading them to the sea. Conversations with Shri Satyabrata Samal and team member Miss Monalisha Mohapatra, and Shri Dibakar significantly deepened my understanding of the Arribada phenomenon.

Despite these efforts, Olive Ridley turtles continue to face significant challenges. Studies conducted globally across Olive Ridley turtle nesting sites (known as arribadas) indicate that egg hatching success rates fluctuate significantly, ranging from 13% to 76%. This variation is influenced by several factors, with an average hatching success rate of approximately 45%. Furthermore, it is estimated that only about 1 in every 1000 hatchlings survives to reach adulthood, facing numerous threats from both natural predators and human activities. Given these challenges, sustained conservation efforts are essential to safeguard the survival of these remarkable creatures.

Witnessing the Arribada: A Guide to Responsible Observation

Experiencing the Arribada is a truly remarkable event. However, it's vital to remember that Olive Ridley sea turtles are vulnerable, and Odisha's nesting sites are critical to their survival. As responsible observers, we must adhere to specific guidelines to protect these turtles during their nesting season. Here's how you can help:

Dos:

• Visit during the nesting season: The best time to witness mass nesting is usually between February and April. Check with local authorities or tour operators for the exact timing.

• Maintain a safe distance: Observe the turtles from a respectful distance, allowing them to carry out their natural nesting process undisturbed.

• Keep noise levels down: Avoid making loud noises or sudden movements that might startle the turtles.

• Follow instructions: Listen to the guides and forest officials and adhere to their instructions. They are there to protect the turtles and ensure your safety.

• Report any disturbances: If you witness any activities that might harm the turtles or their nests, report them to the authorities.

• Support conservation efforts: Contribute to the conservation of Olive Ridley turtles by donating to relevant organizations or volunteering in conservation programs.

Don'ts:

• Use bright lights: Flashlights and camera flashes can disorient the turtles and disrupt their nesting process. If you must use a light, opt for a red-filtered one.

• Touch the turtles or their eggs: Handling the turtles or their eggs can cause stress and harm them. It's also illegal.

• Leave trash behind: Littering can pollute the nesting sites and harm the turtles. Carry out all your trash and dispose of it responsibly.

• Use vehicles on the beach: Driving on the beach can damage nests and disturb the turtles. Park your vehicles in designated areas.

• Disturb the nesting process: Do not approach a turtle that is nesting or try to interfere with the process in any way.

• Feed the turtles: Feeding the turtles can alter their natural behavior and make them dependent on humans.

By following these dos and don'ts, you can contribute to the conservation of Olive Ridley turtles and ensure that these magnificent creatures continue to thrive in their natural habitat.

Conclusion:

Odisha is a land of grand gatherings, both human and animal. Just as the Puri Rath Yatra draws millions of devotees in a spectacular display of faith and unity, the mass nesting of Olive Ridley sea turtles along its coast presents a breathtaking natural spectacle of comparable scale.  In both instances, the sheer volume of participants, be it humans pulling chariots or turtles emerging from the sea, creates a profound sense of awe. These events, one a testament to spiritual devotion and the other to the primal drive of nature, transform the Odisha landscape into a stage for extraordinary mass congregation, highlighting the region's unique ability to host gatherings of immense scale and significance.

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