UWA Oceans Institute

Cross-cultural knowledge supports dolphin conservation

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Australian snubfin dolphin (Dr Deborah Thiele)

OCEANS ONLINE     ISSUE 2. JUNE 2015

Oceans Institute researcher, Phil Bouchet, shares his experience collaborating with Indigenous ranger groups from the Kimberley during a year-long project assessing dolphin populations in Roebuck Bay

Together with Indigenous Ranger groups from the Kimberley, researchers from the Australian National University (Dr Deborah Thiele), the Department of Parks and Wildlife (Dr Holly Raudino, Dr Kelly Waples), the UWA Oceans Institute (Phil Bouchet) and the Kimberley Land Council (Frank Weisenberger) have combined traditional and contemporary scientific knowledge to yield new insights into the abundance and broad-scale distribution of Australian snubfin dolphins.

Snubfin dolphins (Orcaella heinsohni, see above picture) – named for their miniature dorsal fins – are small, elusive cetaceans endemic to the shallow waters of northern Australia and Papua New Guinea. Only formally described in 2005, the enigmatic species remains very poorly understood and now faces increasing threats from inshore developments, particularly along WA’s tropical coast.  

In collaboration with the Bardi Jawi, Dambimangari, Uunguu and Balanggarra Rangers and Traditional Owners of the Kimberley Land Council’s Kimberley Ranger Network, Dr Thiele (Australian National University) has been conducting field surveys across the Kimberley for over a decade with the aim of building a picture of where snubfin dolphins occur throughout this remote and often inaccessible region. She and her team recently combined this information with an extensive collection of public sighting reports to estimate the animals’ relative extent of occurrence (EOO) and area of occupancy (AOO) between Broome and the Northern Territory state border.      

“The EOO and AOO are two different ways of looking at a species’ range - and both are important measures in the Red Listing process for the International Union for the Conservation of Nature (IUCN)”, Dr Thiele said.  

“Our study confirmed the presence of snubfin dolphins throughout the inshore waters of the Kimberley but revealed that the animals only occupy a small proportion of this larger landscape. These results support previous genetic studies showing that the dolphins live in small metapopulations with limited mixing across their range. Additional data on distribution and abundance will be required to assess the species’ conservation status further.”  

The year-long project funded by the Australian Marine Mammal Centre also focused on assessing the number of individuals using Roebuck Bay, a local hotspot thought to harbour the second largest population in the country.   Phil Bouchet noted that “the goal was to not only yield an abundance estimate for this key area but also to contrast two types of mathematical models (mark-recapture and distance sampling) commonly used for estimating cetacean numbers.”  

“Both have merits but may not be equally relevant in every management context. By comparing their performance, precision and information requirements, we hope to provide a clear blueprint that can help prioritise future research and monitoring, maximise knowledge gains and support positive conservation outcomes for this data-deficient species”.  

The study will be published later this year.


Read more about this month's activities at Oceans Online.