Sumedha Korgaonkar

"Intensive Survey of a Lesser Known Population of Olive Ridley Turtles with an Unusual nesting Period Along the Saurashtra Coast of Gujarat, West Coast of India."

Background

The circum-tropically distributed olive ridley turtles (Lepidochelys olivacea) have two distinct populations based on their nesting behavior.  India harbors both these populations where mass nesters are found on the Orissa coast of east India and solitary nesters are found nesting on the rest of the coastline.  IUCN debatably changed the status of all populations of this species to vulnerable based on the population estimation of mass nesters. This has led to ignorance of basic life history study and conservation efforts for solitary nesting populations from varied geographical ranges.  The solitary nesters are known to be distinct in behavior from the mass nesters. Globally the compilation of life histories, genetic data and threats assessment for this species have lead to developing 8 management units globally, called regional management units (RMU).  Indian Ocean west is considered to be a putative RMU due to lack of this data. 
In India, most of the research is focused on mass nesting populations on the Orissa coast, and the solitary nesting populations are highly ignored. The west coast of India has exclusive solitary nesting populations.  Gujarat coast has 68% of green turtle and 32% of olive ridley turtle nesting sites.  As Gujarat has predominantly endangered green turtle nesting sites, most of the survey reports emphasize this species rather than the olive ridley.  According to a 2012 survey report on sea turtle status, the peak nesting period of olive ridley turtles in Gujarat is July, which very unusually coincides with the monsoon period of the west coast of India.  On the rest of the west coast of India it is January or February.  Though useful, this survey reported nesting of this species by indirect observations and the results seem ambiguous.  Apart from this survey, not much literature is available confirming this unique nesting. Few locals working as beach managers patrolling the beach during the nesting period of green turtles have confirmed this report and the fact is denied by forest officials. No beach patrolling is done during the monsoon period from June until September.  In 2018 during a pilot study, a single nest of an olive ridley turtle was found in early August which corroborated the survey report.  The finding of a nest confirmed the unusual nesting period of this species.  Some 5 decades back, the olive ridley turtles used to nest in adjoining Maharashtra state coastline during the late monsoon period suggesting its nesting period has been reduced and restricted in rest of the west coast of India.  With this background it is hypothesized that there might be the subpopulation or ancient stock population of olive ridleys within the geographical range of  the Arabian sea with a further possibility of them being residential near Gujarat coast.  This project proposes an intensive survey of sandy beaches from Dwarka to Mangrol from June till September 2019 involving local residents.  The foraging range will be explored for the first time by a novel technique of stable isotope analysis (SIA) of hatched egg shells. 

 

Project Site

The project site is spread from Dwarka in Jthe amnagar district to Mangrol in the Junagadh district, approximately 100km in length (Latitude: 220 21’ 20’’ N – 210 05’ 10’’N Longitude: 680 57’ 25’’ E – 700 08’ 23’’ E).  Based on a 2012 survey and feasibility of patrolling, 11 study sites have been selected each having a minimum of 4 km in length.  This region receives scant rainfall but has moderate temperature from June to September.  The coastline has wide sandy dissipative beaches with highways or thick thorny bushes adjoining the beaches.  At some places like Madhavpur, Mangrol, Okhamadhi tourists and locals can easily access the beach while some beaches are completely isolated.

Objectives, Methodologies and Timeline

A pilot survey of the nesting sites has been conducted in June 2017.  The lead researcher has met local NGOs, forest officials of Jamnagar and Junagadh and beach managers appointed by the state forest department for hatchery management of Green turtles.  Necessary permissions have already been procured from the Chief Wildlife Warden of Gujarat State Forest Department for conducting research. 

Expected Outcomes

Globally this species is considered as a model species for sea turtle research.  The proposed project with its objectives will explore the distinctiveness of this hypothesized subpopulation, focusing on life history studies filling the knowledge gap.  Preliminary work on population distinction and foraging range will be done for first time in sea turtle research in India by C13 stable isotope analysis.  The proposed project with its outcome will initiate the conservation effort for this ignored species in Gujarat.  The project will form a strong base for further research on population assessment, conservation status and development of management strategy

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