@article {72068, title = {Cetacean Distribution and Diversity in Lakshadweep Waters, India, Using a Platform of Opportunity: October 2015 to April 2016}, journal = {AQUATIC MAMMALS}, volume = {46}, year = {2020}, month = {01/2020}, pages = {80-92}, abstract = {

Prior stranding records suggest that at least 12 cetacean species occur within the Lakshadweep archipelago off the southwest coast of India. These islands consist of coral atolls and form the northern part of the undersea Chagos-Laccadive ridge. Distinct oceanographic features, seasonal monsoon cycles, and high productivity make this region a potentially rich cetacean habitat. In this article, we report findings from the first systematic visual cetacean surveys, which were conducted from high-speed passenger ferries that sail between nine Lakshadweep islands. The surveys were carried out between October 2015 and April 2016 during both the northeast monsoon (October to December) and inter-monsoon (January to April) seasons. We used a line-transect survey framework to record sightings as well as group size estimates. We documented 139 sightings over 3,880 km of which 78 sightings were during systematic survey effort. Eight odontocete species were confirmed from these sightings: Stenella longirostris, S. attenuata, S. coeruleoalba, Tursiops spp., Globicephala macrorhynchus, Pseudorca crassidens, Grampus griseus, and Feresa attenuata. One Balaenoptera sp. was also encountered during this survey. S. longirostris was sighted the most often (n = 22) followed by Tursiops spp. (n = 18) and G. macrorhynchus (n = 13). We documented significantly higher sightings in the northeast monsoon season compared to the inter-monsoon season. Along ferry routes, cetacean species differed significantly from each other with respect to their associations with seafloor slope gradients and distances to nearest landmass. We encountered mixed species assemblages of G. macrorhynchus with Tursiops sp. and S. attenuata with Tursiops sp. Given the confirmed high cetacean diversity and occurrence in this region, there is a need for in-depth, long-term studies on biogeography, ecology, and population status of cetaceans here.

}, doi = {10.1578/AM.46.1.2020.80}, author = {Panicker, Divya and Sutaria, Dipani and Kumar, Ajith and Stafford, Kathleen M} } @article {45440, title = {Description and classification of Indian Ocean humpback dolphin (Sousa plumbea) whistles recorded off the Sindhudurg coast of Maharashtra, India }, journal = {Marine Mammel Science}, volume = {34}, year = {2018}, month = {07/2018}, pages = {755-776}, abstract = {

The Indian Ocean humpback dolphin (Sousa plumbea), a common cetacean species in India, has a diverse vocal repertoire, which to date has not been described in detail. This study focused on analyzing their whistle vocalizations. Humpback dolphins were recorded off the Sindhudurg coast of Maharashtra, India, and 2,260 whistles were analyzed for their acoustic characteristics. Whistles spanned a wide frequency range between 2.3 kHz and 33.0 kHz, with durations ranging from 0.01 s to 1.60 s. Whistles were categorized into seven contour classes based on their qualitative properties. A classification and regression tree (CART) analysis was used to quantify variability between the seven contour classes using the measured acoustic features. Based on the CART analysis, frequency gradient, minimum slope, maximum slope, beginning and ending slope accounted for most variability between whistle types. CART resulted in an overall classification accuracy of 89.5\%. This study provides a detailed description of acoustic features and qualitative properties of humpback dolphin whistles from the northwestern coast of India. Further comparisons of acoustic data from Sousa populations along the Indian coast are necessary to determine possible geographic variations in whistle characteristics and whether the variations are driven by environmental or genetic factors or a combination of both.

}, doi = {10.1111/mms.12479}, author = {Bopardikar, I and Sutaria, Dipani and Sule, M and Patankar, Vardhan and Klinck, H} } @article {30081, title = {Indian Ocean humpback dolphin (Sousa plumbea) estuary-use patterns in Kochi harbor, India}, journal = {MARINE MAMMAL SCIENCE}, volume = {34}, year = {2018}, month = {01/2018}, pages = {208-219}, doi = {10.1111/mms.12438}, author = {Panicker, Divya and Haris, Asad and Sutaria, Dipani} }