On being alerted by fishermen, a team headed by Mandapam wildlife ranger S Sathish visited the spot and examined the carcass.

According to wildlife officials, the whale shark is a protected species under schedule I of Wildlife Protection Act. It is also an endangered species under the International Union for Conservation of Nature (IUCN).

The whale shark that washed ashore on Tuesday was 18 feet long with a circumference of 10 feet. "Whale shark is one of the shark species found in the Gulf of Mannar area. The cause of death is found to be heavy internal injuries it has suffered when it either hit a rock or a big vessel," Sathish said.

During postmortem, wildlife officials found a plastic spoon in its digestive system. "It is a stark revelation how plastic waste is getting into the marine eco-system. The marine species can't distinguish between a floating plastic and prey. We should avoid dumping plastic waste inside sea," Sathish added.

Whale shark is filter feeder, one of the three filter feeding sharks in the world, the other species are basking shark and megamouth shark. Water along with feed like plankton and fish larvae are suck by the fish and filtered through gills retaining the food. The plastic spoon should have been sucked into its digestive system in this manner, wildlife officials said.

The carcass was buried on the beach.

It is a second incident of whale shark washing ashore dead recently. On May 7, a whale shark weighing more than 350kg for the length of 10 feet and 3 feet circumference was found dead at Kunthukal beach.