Olive Ridleys tagged in Maharashtra travel to coastal waters in Gujarat, Karnataka

Olive Ridleys are found in warm tropical parts of the Indian and Pacific oceans, travelling thousands of kilometres into the deep water

Mumbai: Of the four Olive Ridley turtles being monitored by the state forest department through radio tracking devices, two have exited the state’s coastal waters in the past week, entering Gujarat and Karnataka, respectively. The two turtles have covered a combined distance of close to 350kms away from their nesting sites.

Olive Ridleys tagged in Maharashtra travel to coastal waters in Gujarat, Karnataka

In all, five turtles have been fitted with platform transmitter terminals (PTTs) this year, allowing researchers to monitor their migratory paths after laying their nests on the Maharashtra coast. Prathama and Savani were the first to be tagged on January 25, followed by Vanasharee, Laxmi and Rewa in February.

While Vanashree and Laxmi have not ventured too far from their nesting sites and are still roving in nearshore waters in the state, Prathama has ventured into deeper waters near Diu in Gujarat, more than 250kms away. Rewa, on the other hand, is moving southwards and was last located around about 150kms away from her nesting beach. The location is around 80kms from Mangalore. It is suspected that the turtles may be heading toward the Middle East and Sri Lanka, respectively.

Researchers had lost contact with the fifth turtle, Laxmi, around March 12. It is suspected that the PPT device may have malfunctioned, or that the turtle may have died. “We believe that the turtles are waiting in shallow waters for the ocean currents to become favourable for their onward journey, either toward Sri Lanka and the Lakshadweep or towards Oman and the Somali coastline. We will also be able to track their journey back to Maharashtra later this year once nesting season begins around November,” said Harshal Karve, a marine biologist with the Mangrove Foundation, who is working on this project.

While satellite monitoring of Olive Ridleys -- whose conservation status has been assessed as ‘vulnerable’ by the International Union for the Conservation of Nature (IUCN) -- has been previously carried out on India’s east coast which sees mass nesting populations, this marks the first time such a study has been commissioned in the west, where the nesting populations of these turtles are sporadic. The study received approval in October 2020, during the third governing body meeting of the Mangrove Foundation.

According to the state forest department’s mangrove cell, under which the Mangrove Foundation works as an autonomous, registered society, approximately 600 Olive Ridley turtles find their way to nesting sites across prominent beaches in Ratnagiri, Sindhudurg and Raigad districts of Maharashtra every winter. Olive Ridleys are found in warm tropical parts of the Indian and Pacific oceans, travelling thousands of kilometres into the deep water, and only the females return to the original breeding sites within a minimum of two years.