Habitat associations of cetaceans and seabirds in the tropical eastern Indian Ocean

Abstract

There is an increasing demand for integrated pelagic surveys to support ecosystem-based management of marine environments and their associated marine life. The Browse Basin in the tropical eastern Indian Ocean was surveyed using ship line transects to determine habitat associations of cetaceans and seabirds with submarine topography and local oceanographic conditions during winter and spring 2008. Fourteen species of cetaceans, including the data deficient pygmy blue whale, and 23 species of seabirds were encountered throughout the basin. Aggregations of both cetaceans and seabirds were observed at two significant submarine topographic features, Scott Reef and Browse Cliffs, particularly during spring when encounters and abundances of odontocetes were far greater. The attraction of cetaceans and seabirds to Scott Reef and Browse Cliffs was likely foraging-related given these features were associated with upwelling and elevated biomass of krill and fish. Sub-mesoscale sea surface temperature and chlorophyll a fronts also occurred in vicinity to Browse Cliffs and the shelf environment. The Browse Basin is an important, and potentially predictable, foraging ground for a variety of top predators, and their occurrence would have implications for the current and future management practices of oil and gas industries operating in the region.