Sightings and behavioral observations of Indo-Pacific Humpback Dolphins Sousa chinensis (Osbeck, 1765) along Chennai coast, Bay of Bengal

Rahul Muralidharan

doi:10.11609/jott.o3454.5002-6

Abstract

Boat-based surveys were used to investigate the presence of Indo-Pacific Humpback Dolphins Sousa chinensis along the coast of Chennai, Tamil Nadu, India. Notes were collected on behavior, group size, coloration patterns and group composition on sighting cetaceans during the surveys. Four groups of Indo-Pacific Humpback Dolphins were sighted near-shore in the month of February 2011, between 10-25 m depth with an average group size of 20 individuals of which 10 individuals were photo-identifiable. Dominant group behavior was aerial display, feeding and traveling. This study gives a basic idea of presence, threats and habitat use of Humpback Dolphin areas along Chennai coast.

Highlights

Boat-based surveys were used to investigate the presence of Indo-Pacific Humpback Dolphins Sousa chinensis along the coast of Chennai, Tamil Nadu, India
Indo-pacific humpback dolphins were identified based on the coloration pattern and hump under the dorsal fin (Jefferson et al 1993)
Due to the limited survey effort in our study area, we cannot ascertain if humpback dolphins are resident along the Chennai coast or are local migrants from close-by estuaries, but we hypothesize the latter based on scattered reports from fishers and from our observations

Summary

Introduction

Boat-based surveys were used to investigate the presence of Indo-Pacific Humpback Dolphins Sousa chinensis along the coast of Chennai, Tamil Nadu, India. Indo-Pacific Humpback Dolphins Sousa chinensis have been recorded all along the Indian coast, from vesselbased and shore-based sightings, stranding records, incidental catch data, and museum specimens (Parsons 1998; Kumarran 2002; Parsons 2004; Sathasivam 2004; Sutaria & Jefferson 2004; Afsal et al 2008; Anoop et al 2008; Reeves et al 2008; Yousuf et al 2008; Muralidharan 2011; Kumaran 2012; Vivekanandan & Jeyabaskaran 2012). We surveyed the Chennai coast for presence and behavior of S. chinensis, in relation to depth, distance from the shore and time of the day

Methods

Results

Conclusion