Indian Ocean humpback dolphin (Sousa plumbea) estuary-use patterns in Kochi harbor, India

[Extract] Coastal and estuarine ecosystems have high productivity, high variability in environmental conditions, and increased human activity, making them a vital but vulnerable habitat for many cetacean species (Ryther 1969, Ballance 1992, Costanza et al. 1997). Estuary‐associated dolphins have a range of responses that help them to adapt to changing environmental conditions such as spatial or temporal variations of use, often depending on the local conditions; hence it is critical to carry out site‐specific studies to understand the importance of estuaries for dolphins (Fury and Harrison 2011). The Indian Ocean humpback dolphin (Sousa plumbea) is a near‐shore species, highly associated with estuaries and this preferred habitat type overlaps with high human use areas (Karczmarski et al. 2000b, Hung and Jefferson 2004). Sousa plumbea ranges geographically from South Africa to Myanmar (Jefferson and Rosenbaum 2014). The main threats identified to this species (classified by IUCN under the umbrella of S. chinensis) are intensive gill‐net fishing and estuarine habitat degradation (Reeves et al. 2008)