Suitable habitats of two coastal cetaceans along the northern Arabian Sea: Important marine mammal areas susceptible to conservation gaps

Coastal cetaceans are often selected as a biodiversity surrogate in ecosystem-based conservation planning. In the northern Arabian Sea there is insufficient information on suitable habitats for the Indo-Pacific finless porpoise and Indian Ocean humpback dolphin for planning protection.Suitable habitats for the Indo-Pacific finless porpoise and Indian Ocean humpback dolphin were projected using the MaxEnt model in the present study. The variable contributions in MaxEnt exercises and characteristics of the major habitats were used to represent the ecological niches of these two cetaceans.Along coastal waters of the northern Arabian Sea, bathymetry was the most significant variable that influenced the distribution of the Indian Ocean humpback dolphin, which prefers water 2-5 m deep. The Indo-Pacific finless porpoise prefers 6-20 m deep water and its distribution was influenced by bathymetry, sea-surface temperature and chlorophyll-a concentration.Suitable habitats identified by this study provide a baseline from which to evaluate the impact of anthropogenic activities in coastal and estuarine waters, assist marine development planning and guide marine protected area (MPA) designations. Effective MPA designation would include ca. 30% of major habitats to accommodate viable populations and sufficient biodiversity richness to maintain a functioning ecosystem. Data used in the present study may be subject to sampling heterogeneity and thus coastal waters not included as suitable habitats would require further investigation for possible omission bias.Actions necessary for conservation of the Indo-Pacific finless porpoise and Indian Ocean humpback dolphin include designating no-take zones or MPAs, banning industrial fishing while restricting artisanal fishery activity and mobilizing community-based conservation campaigns for major habitat protection. As such, further data on distribution, density and environmental variables related to cetaceans are needed to inform any conservation efforts.