Help to save rare humpback dolphins
Flinders researchers have confirmed the importance of the remote Ningaloo Reef as a conservation site of significance for the rare and secretive Australian humpback dolphin.
The Ningaloo Reef region in northern Western Australia hosts one of the largest populations of the threatened Australian humpback dolphin – supporting the need for future conservation and management initiatives in the Pilbara region, the Flinders University researchers say.
An extensive three-year study found about 130 of the elusive and cryptic humpback dolphins living in the 130 km2 study area, or roughly one humpback dolphin per square kilometre, making this density the highest recorded for this species which is found in northern Australia – from Shark Bay in WA to Queensland-NSW border – to south of New Guinea.
"We have identified an important area for this poorly known threatened species, and most of our study area lies within a Marine Protected Area (MPA)," says lead researcher, Flinders PhD candidate Tim Hunt.
"This gives us a great opportunity to utilise the regulatory framework of the MPA on which to base the management of human activities that have the potential to impact this fascinating endemic species."
Mr Hunt says the North West Cape, located about 1,500km north of Perth, is part of the marine protected area of Ningaloo Marine Park but next to one of Australia's fastest growing and resource-rich regions, the Pilbara.
"These current and projected coastal developments in the adjacent (non-protected) Pilbara region equate to potential cumulative pressures on humpback dolphins in the future," he says.
"Our findings represent a baseline from which to develop long-term studies through which we can gain a more complete understanding of Australian humpback dolphin population dynamics as a basis for their future management of coastal waters."
The latest study, led by Biological Sciences PhD candidate Tim Hunt and senior lecturer Dr Guido Parra who leads the Flinders University Cetacean Ecology, Behaviour and Evolution Lab (CEBEL), involved boat-based surveys and photo-identification methods from 2013 to 2015.
The recently described Australian humpback dolphin (Sousa sahulensis) is one of two endemic dolphin species inhabiting the northern Australian coastline.
The Australian snubfin dolphin (Orcaella heinsohni) was formally described in 2005, and ranges from the Kimberley region in WA to central Queensland. Coastal development has been identified as a major threat to the both species' persistence.
A third coastal dolphin species, the more commonly known bottlenose dolphin (Tursiops sp.), is found throughout Australia, and has often been seen in groups associating with Australian humpback dolphins in the Ningaloo Reef region.
Dr Parra says better understanding of the ecology and conservation biology of the humpback dolphin is vital to the famous Ningaloo Reef region.
"Many people know about the whale sharks and humpback whales that visit the iconic Ningaloo Reef every year, but few know about our Australian humpback dolphin that occurs there year round," Dr Parra says.
"Understanding the ecology and behaviour of this threatened species in what appears to be an important habitat for them is critical for improving the scientific basis for their conservation and management."
More information: TN Hunt et al. Demographic characteristics of Australian humpback dolphins reveal important habitat toward the southwestern limit of their range, Endangered Species Research (2017). DOI: 10.3354/esr00784
Provided by Flinders University