Risso’s dolphin washed ashore at SadrasKuppam

G. Sundaram of Sadras Kuppam and member of the Marine Mammal Stranding and Rescue team from TREE Foundation responded to a call about a dead dolphin around 7.30 am, on 24th of May 2018.The dolphin washed ashore was a confirmed as Risso’s dolphin as it had a furrow on the head which is the most striking featureof its species. The melon was broad, squarish in profile, and creased in front by a characteristic longitudinal furrow, like the furrow on the elephant’s forehead, and stubby snout. It had a distinctive beakless head shape and a body that is noticeably more robust in the front half than in the back. Sub adults and adults have many rake marks on their body. The features were compared and then it was identified asRisso’s dolphin (Grampus griseus).Normally Risso’s Dolphin have 2 to 7 pairs in the front of the lower jaw and none in the upper jaw. As per the inspection carried out on the stranded dolphin, no teeth were found, therefore based on the non-presence of teeth and its length it could be a dolphin calf.

The stranded dolphin was 56 inch long and weighed over 35 kilograms. The tail of the dolphin was measured around 15 inch wide. The dorsal fin of the dolphin was measured around 12 inch long and pectoral flippers were 14 inches long. The gape (mouth opening) of the dolphin was 9 inch long.There were no visible wounds or markstherefore the cause of death of the calf may be due to drowning by entangled in fishing gear.

This is a widely distributed species, inhabiting deep oceanic and continental slope waters from the tropics through the temperate regions in both hemispheres. These large dolphins are often seen surfacing slowly, although they can be energetic. Risso's dolphins feed on crustaceans and cephalopods, but seem to prefer squid. Squid bites may be the cause of some of the scars found on the bodies of these animals. Under the name "grampus", it was one of the royal fish which were traditionally the property of the English Crown.Risso's dolphins generally do not approach boats, but occasionally surf bow wavesRisso's dolphins have been taken in small numbers, (both incidentally and intentionally) in drive, gillnet, seine, and harpoon fisheries throughout the species' range. They are commonly taken cetacean by fisheries, providing fish and meat for human consumption and fish bait; stocks therefore may be adversely affected. Mass slaughtering of these dolphins is also a common practice.

The carcass would attract jackals and crows, so after a full external examination the dolphin was buried 50 metres above the high tide line. Sea Turtle Protection Force Members of TREE Foundation also did this as a sign of respect for the mammals. TREE Foundation has been recording unusual number of cetacean (dolphins, whales and porpoises) and so far we have recorded 28 dead stranded dolphin and 176sea turtles dead stranded along Kanchipuram coast from the start of this year. Though there are certain traces where the most probable cause of death can be identified, the exact reason is still a matter of consideration. In the majority of cases the team have assessed that the death has been caused by some sort of fisheries interaction.Helpful citizens are requested to contact 94440 52242 when they see any stranded marine animals along the coast. For any more enquiries, contact TREE Foundation at 94443 06411.