Coastal dolphins in north-western Australia: The need for re-evaluation of species listings and short-comings in the Environmental Impact Assessment process.

Abstract

LITTLE is known about the distribution, abundance and behavioural ecology of dolphins in the tropical north-west of Australia. This region is remote, and until recently, has had a relatively low human population. Two of Australia’s tropical coastal dolphin species, the Australian Snubfin Orcaella heinsohni and Indo-Pacific Humpback Dolphins Sousa chinensis (“Snubfin Dolphin” and “Humpback Dolphin”, hereafter) are known to occur in the region. Australia-wide, the only scientific publications on these two species come from a few studies from eastern Queensland, where both species live in “populations” of 50–100 individuals (Parra et al. 2006a; Cagnazzi et al. 2009) that are genetically isolated from one another (Parra 2011); have small home ranges; and are found in near-shore areas, typically within 3- 5 km of the coastline (Parra 2006; Parra et al. 2002, 2004, 2006a,b; Cagnazzi et al. 2009). In eastern Australia, both species forage on coastal/estuarine fish and cephalopods, which is further evidence of their reliance on the near-shore environment (Parra and Jedensjö 2009). According to population sizes in Queensland, and the extent of potentially suitable habitat along the north-west coast, the total numbers in Western Australia are likely to be in the low thousands of individuals (i.e., < 5000). The combination of these life-history characteristics may render Snubfin and Humpback Dolphins particularly vulnerable to local extinctions due to human activities such as habitat modification and increased shipping and boating activity (Frankham 2005; O’Grady et al. 2006). In this Essay, we review the current extent of coastal developments in the waters of north-west Australia. Then we discuss the conservation and management implications of this in relation to coastal dolphins, particularly Snubfin and Humpback Dolphins. We also appraise the current, non-targeted methods being used to survey marine mammal populations for environmental impact assessments (EIAs), highlighting their inadequacy for coastal dolphins. Finally, we make recommendations that should improve government decision making processes for the long term conservation of these two species.