Coastal Conservation Foundation

THT Research Grant 2025

Project Title:

Sounds, Spaces and Sizes: Developing an Interdisciplinary Conservation Framework for Mumbai’s Highly Threatened Dolphins

Project Brief:

This project by the Coastal Conservation Foundation aims to develop the first conservation framework for the Indian Ocean humpback dolphin (Sousa plumbea) (IOHD), a highly threatened coastal dolphin population near Mumbai. The study will use advanced methodology and technology to estimate dolphin occurrence and population sizes. The ecological and social dynamics of the population, along with the anthropogenic activities of the metropolis, will be analysed to develop a conservation and management plan. The Coastal Conservation Foundation had initiated risk assessments for the dolphin population in 2022, and through this study, will further assess the threats posed by anthropogenic sounds. The Indian Ocean humpback dolphin (IOHD) is an endangered species found in the nearshore waters of India’s west coast. In Mumbai, research has shown that IOHD is found up to 7 km from shore, with its habitat overlapping with fisheries and the ongoing development of a large-scale sea bridge (Modi et al. 2024). These overlapping zones produce chronic sounds, in the case of fisheries, and short-term, high-amplitude sounds, in the case of at-sea construction.

Despite this, no environmental impact assessment has been undertaken to check the effects of these activities on the population of IOHD in Mumbai or elsewhere in the country. This study proposes an interdisciplinary assessment to understand the short- and long-term effects of sound pollution. The team will build a baseline of population size, continue monitoring occurrence patterns, and use novel acoustic techniques to evaluate the impact of anthropogenic sound. The findings will inform key recommendations for the conservation of the IOHD

Project objectives:

The project has the following objectives:

  • Estimate the population size of the IOHD in the coastal waters of the Mumbai metropolis.
  • Document the spatiotemporal variability in IOHD distribution and assess potential responses to anthropogenic activities in the area.
  • Measure underwater anthropogenic sound sources in the IOHD habitats of Mumbai.
  • Develop a mitigation framework towards long-term conservation of the species.
Project Location:
  • Mumbai coastal waters, Maharashtra