New records of neonatal whale sharks (Rhincodon typus) from the Arabian Sea and discovery of a possible natal ground on the Gujarat coast, India

Abstract

Background To overcome the issue of accidental mortality in fishing nets, the Government of Gujarat started promoting the release of entangled whale sharks by providing adequate compensation for the gear loss incurred by the fishers during the release. The attempt to save entangled whale sharks was a great success. However, constant follow up and rescue information collection from the fishers was essential to monitor the rate of entanglement and release. The current reporting of neonatal whale sharks from the Indian coast was the result of these interactions with fishers. Approach Youngwhale sharks are rarely seen, with only 14 encounters with neonatal whale sharks reported in the scientific literature. The project sociologist is in constant touch with the fishers and collects all the information about whale shark sightings and rescue. The importance of recording the size class of whale sharks was detailed to the fishers. Results Atotal of four whale shark pups (size range 60–100 cm) were recorded during 2013. Interviews with the fishers of Sutrapada fishing village in Gujarat revealed that they found a whale shark pup entangled in a fishing net on 5th March 2013, exactly 10 km offshore of the Sutrapada headland. The length of the pup was approximately 60 cm. The second report is from 15th March 2013, approximately 10 km offshore of the Sutrapada headland. Fishermen from Sutrapada fishing village found the pup whale shark entangled in a gill net and released it. The fishermen recorded the entire event using a mobile telephone. Ocular estimation of the size of whale shark pup from the provided video by comparing with a fisherman's palm was approximately 60 cm. While intervening the fishers during the monsoon fishing ban along the Saurashtra coast (June–July), we came to know that the fishers saw one dead whale shark pup beached near the Sutrapada fishing village on 6th April, 2013. According to the fishers, the sighting of dead whale shark pups is not a common incident and it might be the first incident where fishermen come across a dead whale shark pup. The size of the pup was nearly 100 cm. The pup was found near the rocky shores of the beach and fishermen observed some scars over the head and second dorsal fin. Fishers also reported a whale shark pup swimming on the water surface 20 km off Sutrapada coast. Conclusions Neonatalwhale sharks are thought to have limited swimming abilities compared to juveniles and adults. Thus the new records of pups of size range 60–100 cm indicate that this region is a pupping ground for whale sharks.