Soundscape components in a shallow-water zone off the coast of Goa

Abstract

Underwater acoustic data were collected around Grande Island off the coast of Goa, India using moored autonomous recording equipment during March 2016 and March 2017 for four and ten days, respectively. The study site, a shallow-water area in the vicinity of the Zuari river estuary and in proximity of a major shipping port, is presumed to lie along cetacean migration routes. Two different locations were chosen for data collection during each year—a reef site and an off-reef site. All four datasets were dominated by circadian choruses of fish and snapping shrimp. Fish species that were found to contribute significantly to the soundscape includes terapontidae, toadfish, and sciaenidae. Other biological contributions included vocalizations from cetaceans. For example, beaked whale clicks were observed in the 2016 recordings and humpback whale vocalizations were observed for six days in the 2017 recordings. Anthropogenic influence in the soundscape remained low during both years and the only contributing sources were sporadic vessels passing in the vicinity. Given the low measured levels of anthropogenic contribution, the findings of this study could be used as a baseline for performing impact assessments during any future offshore operations in the region.