Will the spectacular sight of mass congregation of endangered Olive Ridley sea turtles for mating and nesting on the beaches of Gahirmatha become history?

The beaches coming under the Gahirmatha Marine Wildlife Sanctuary have shrunk considerably. A 32-km-long beach has shrunk to less than one kilometre in the past 35 years.

Gahirmatha is one of the first rookeries of turtles discovered along the Orissa coast.

A group of researchers from the Wildlife Institute of India and the Orissa Forest Department noticed the trend while studying the offshore distribution and migration pattern of Olive Ridleys along the country's east coast.

While presenting the outcome of the study spanning from 2007 to 2010 here recently, B. C. Choudhury, WII scientist and principal investigator of the study, said: “When as a researcher I worked in 1975, we used to walk a 32-km stretch beach where nesting used to take place. When the fragmentation occurred, at that point of time the nesting beach was six km long. And today it is about 950 metre.”

Fragmented space

In 2004, Islands of Nasi-I and Nasi II in Gahirmatha used to be continuous, but now the space was fragmented, Mr. Choudhury said. “Smaller patches of beach are often submerged. But when these are exposed, there is very little space available for nesting by turtles.” The area available for nesting was 1,80,000 square metre in 2004.

Mr. Choudhury said that in 2009, all smaller patches went under water and a very small piece of extended sand bar got attached to the Wheeler Island, which was being used by the Defence Research Development Organisation for missile testing. The nesting took place on the sandbar which was about 78,300 square metre.

“In 2010, the total mass nesting area is about 1,000 metre long by 53 metre width. You can easily calculate what is the total area? And even by wildest stretch of imagination, can you believe that 4.5 lakh turtles will lay their eggs in that area,” the WII scientist asked.

“Nesting by four to five turtles in a square metre area is very high density. Imagine the scenario on one metre square area where the first turtle will lay eggs, the second turtle will probably dig out those eggs. When 1.5 lakh eggs are laid and covered, probably 50,000 eggs are taken out.”

Apart from Gahirmatha rookery, two other mass nesting beaches are located on the mouth of rivers Rushikulya and Devi along the Orissa coast.

The study also said that nesting density (4 to5 turtles per square metre area) was high in Gahirmatha compared to Rushikulya (0.80 to one per square metre area) during the 2009-10 nesting season. Low erosion and sporadic nesting resulted in high hatching success at Devi.

Researchers say beach erosion is the major reason behind the gradual loss of nesting sites of Ridleys. Besides, proper management of turtle nesting has to be put in place as development activities (20 existing projects and 21 proposed ones, including ports along the coast) could prove to be the death-knell for Olive Ridleys.