Orissa boasts of possessing the world's largest known rookery of Olive Ridley sea turtle. Apart from Gahirmatha rookery, two other mass nesting beaches have been located which are on the mouth of rivers Rushikulya and Devi. The spectacular site of mass congregation of Olive Ridley sea turtles for mating and nesting enthralls both the scientists and the nature lovers throughout the world. This unique phenomenon is hardly seen anywhere in India. That rarity of mass congregation and the cruelty meted out to these innocent marine creatures, paved the way for declaration of the stretch of water body from old light house near Batighar to Maipura river mouth as Gahirmatha (Marine) Wildlife Sanctuary.

Location
Gahirmatha is the only marine wildlife sanctuary of Orissa. This was notified as such in Government of Orissa, Forest & Environment Department Notification No. 18805/ F&E dated 27th September 1997 and published in the Orissa Gazette, extraordinary No. 1268 dated 17th October, 1997. It is located between 86 degree 45'57" to 87 degree 17' 36"- East longitude and 20 degree 17' 32" to 20 degree 45'58" - North latitude. The total area of the sanctuary is 1435.0 Sq. Km. which includes 1408.0 Sq. Km. of water body and 27.0 Sq. Km. of land mass including reserve forests, mud flats and accreted sand bars. Core area of the sanctuary consists of 725.50 Sq. Km. and the buffer zone accounts for 709.50 Sq. Km. The entire sanctuary area comes within the revenue district of Kendrapara.

Importance
Olive Ridley sea turtles migrate in huge numbers from the beginning of November, every year, for mating and nesting along the coast of Orissa. Gahirmatha coast has the annual nesting figure between one hundred to five hundred thousand, each year. there has been decline in the population of these turtles in the recent past due to mass mortality. Olive Ridley sea turtle has found place in Schedule - I of Indian Wildlife (Protection) Act, 1972 (amended 1991). All the species of sea turtles in the coastal water of Orissa are listed as "endangered" as per IUCN Red Data Book. The sea turtles are protected under the 'Migratory Species Convention' and CITES (Convention of International Trade on Wildlife Flora and Fauna). India is a signatory nation to all these conventions. The 'Homing' characteristics of the Ridley sea turtles make them more prone to mass casualty. The voyage to the natal nesting beaches is the dooming factor for the sea turtles. Since Gahirmatha coast serves as the natal nesting beach for millions of turtles, it has immense importance on turtle conservation.

Food habits
Olive Ridley sea turtles feed on marine snails, smaller forms of fish, fish eggs, crustaceans and jellyfish. Algal material is also used as food by the Ridleys. Ridleys generally crush and grind the food materials before intaking.
Migration
The best feeding ground of sea turtles may not be the best nesting ground for them. The sea turtles migrate thousands of kilometres to meet both the ends. It has been observed that Olive Ridley sea turtles migrate from the coastal water of Srilanka in the Indian ocean to the coastal water of Gahirmatha in the north. The 'Homing' characteristics and the uncanny ability to orient itself in open sea help the sea turtles to migrate over long distance without getting lost in the vastness of the sea.
Mating
Immediately after the arrival of ridley sea turtles in the coastal water of Gahirmatha, they indulge in matting activities. Males mount over the females and are often seen floating on the surface with the intermittent movement of flippers. Sometimes more than one male is seen mounting over one female. The courtship continues for hours unless there is any external threat. A female will continue to mate with several males throughout the breeding season. Mostly the mating pairs are seen off the coast of Ekakula.
Nesting
The mass nesting behaviour of Olive ridley sea turtles is known as "Arribada". Thousands of female carrying turtles scramble on the nesting beach at Nasi - I & II islands to release the eggs in flask shaped cavities. The turtles scoop the soft sand to a depth of 45 cm with the help of flippers and release 100 to 180 eggs. Before scampering on to the beach, the turtles survey the nesting ground from the sea and incase they smell and danger, they shun the beach and search for safer breeding ground. The urge to release the egg is so intense that they are so oblivious of the presence of any foreigner, at the time of nesting. Generally dark nights are preferred by the ridleys for nesting. It has been observed that nesting takes place once the southernly wind starts blowing. The period of emergence and retreat into the sea after nesting takes 45 to 55 minutes. Due to the shrinkage of the nesting beach, over crowding of turtles is observed during nesting. The eggs which are scooped out by successive nesters is known as "doomed" egg as it would never be able to hatch. Sporadic nesting is also not uncommon. These eggs are mostly damaged by predators. The nesting females emit hissing noise at the time of laying eggs as the intake of oxygen is maximum at that moment. After laying eggs, the female turtle fills up the pit with sand by the flippers and tries to camouflage the pit site. The motor turtle, rams the pit with the help of its body weight.



Hatching
The eggs inside the flask shaped pits, being incubated by sun and the metabolic heat, hatch after 50 to 60 days. The hatching takes place during night or in the predawn period to avoid predation by Jackles, dogs and birds. The walls of the pit gradually collapse, thereby allowing the eggs on the lower strata to rise upwards. After the emergence of hatchlings, they immediately head for the open sea. The tiny replicas of turtles are in a frenzy to enter the sea water. This is the most spectacular sight. The hatchlings orient themselves by the reflection of stars on sea water or by the brighter horizon and head enmasse towards the sea. The hatchlings swim deep into the sea until they reach the sea current. During this period large scale mortality of hatchlings take place. It is studied that 1 in 1000 survives. Bigger fishes, ghost crabs or seagulls either predates the hatchlings. Then the period of "lost year" begins.
Mortality
Every year large scale mortality of Olive ridley sea turtles are observed. The reasons are.
Incidental capture in fishing nets.
Large scale conversion of traditional crafts into mechanised boats.
Release of toxic effluents by the chemically factory at Paradeep.
Predation.

Rampant fishing inside the restricted area is the cause of large scale mortality of ridleys. Fishermen flout all norms with the ultimate aim of catching maximum fish at the cost of sea turtles. Come fishermen even kill the turtles intentionally to get rid of the turtles from their fishing nets.

In order to maximise fish catch, there has been wide spread conversion of traditional crafts into mechanised boats. This has enabled the fishermen to carry long nets into deeper water. Lying of fishing nets in the turtle congregated areas have resulted in more casualties of turtles.

The chemical factories at Paradeep release toxic materials into river Mahanadi, which drains out the contents into Bay of Bengal. Paradeep is on the southern periphery of Gahirmatha Marine Sanctuary. it has adverse effect on the life of sea turtles.

The increase in the number of stray dogs, Jackles, wild boars have spelt danger for the sea turtles. The emerging turtles are attacked and killed by these predators.

The mortality of hatchlings occur due to artificial illumination, birds, ghost crabs, big fishes and other predators.

Sanctuary Management:
An Annual Action Plan is being drawn up for management of the sanctuary. the salient features of management are:
Segmentation of the potential nesting beach.
Establishment of anti-poaching camps.
Turtle co-ordination meeting with the Coast Guard, Police and Fisheries officials.
Awareness meeting with different fishing communities.
Patrolling inside Gahirmatha Marine Sanctuary.
Improvement of nesting beaches.
Eco-development programme for the stake holders in the peripheral villages.
Recording data on mortality and different causes.
Opening of in-situ hatcheries.
Census of emerging turtles for laying eggs.
Protection of nesting sites.
Counting of hatchlings.
Other Problems:
Increase in fishing activities and the spurt in the increase of mechanised fishing vessels.
Changes in the land use policy of mangrove forests in the fringe areas.
Change in the beach profile.
Artificial lighting which dissuades the turtles and the hatchlings.
Blatant violation of CRZ rules.
Increase of vessel movement inside the sanctuary area.

Census Figure (Nesting of sea turtles in lakhs starting from 1985 to 2001)

Year
Nesting

2002-03

75,032

2003-04
2003-04

2,12,091(1st nesting)
26,000  (2nd nesting)

2004-05

2,36,010

2005-06

2,74,793

2006-07

1,47,726

2007-08

3121

2008-09

1,67,222

2009-10

3,56,894

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