Dolphins – Western Australian Marine Science Institution

Project

About the theme

Description

The Australian snubfin dolphin (Orcaella heinsohni, ‘snubfin dolphin’ hereafter) and Australian humpback dolphin (Sousa sahulensis) are poorly-understood species of dolphin whose global distribution is restricted to shallow coastal and estuarine waters of northern Australia and southern New Guinea.

Here, we investigate the population genetic structure and relative abundance of these two species at selected study sites in the Kimberley region of northwestern Australia. We also investigate the application of passive acoustic monitoring (PAM) as an effective technique for monitoring these species in the remote waters of the Kimberley region, with potential applications across northern Australia.

Aims

To provide information on the relative abundance of dolphin populations across the Kimberley
To better understand genetic connectivity between dolphin populations in the Kimberley. examine population genetic structure and gene flow between several locations within the Kimberley region.
To develop Passive Acoustic Monitoring (PAM) techniques for snubfin and humpback dolphins within the Kimberley by: (i) developing an understanding of the underwater soundscape; and (ii) correlating acoustic and visual observations of dolphins to validate species presence, identify acoustic repertoire and examine vocalisation rates.

Methods

Boat based surveys for dolphins were conducted at several key sites across the Kimberley. During these surveys data were collected on location, behaviour and group composition of dolphins, in addition to high quality image of dorsal fins for individual identification purposes (photo-ID).
Small skin/tissue samples were collected from free-ranging dolphins using a remote biopsy darting system. These samples were subsequently analysed to determine sex and measure gene flow between populations from nuclear and mitochondrial DNA markers.
Noise loggers (underwater noise recorders) were deployed on moorings at selected sites (Roebuck and Cygnet Bay) to record dolphin sounds and analyse other sources of ambient underwater noise.
Compact acoustic recorders were deployed on temporary moorings to record dolphin vocalisations in parallel with visual observations from an elevated observation platform (moored ship in Roebuck Bay; elevated land in Cone Bay).
Field work was undertaken in collaboration with Traditional Owners and Marine Park/Wildlife Managers.

Outcomes

Improved understanding of the distribution and relative abundance of snubfin and humpback dolphins at several remote locations in the Kimberley, assisting in the identification of important habitats, management of threats and providing a benchmark for future research and monitoring in the region.
An improved understanding of the genetic connectivity of snubfin and humpback dolphin populations in northwestern Australian waters and the appropriate geographic scales at which to manage them.
Characterisation of the underwater soundscape at two locations in the Kimberley.
Illustration that PAM provides a method of effectively detecting snubfin and humpback dolphins in high-use areas, and an increased information base from which to further develop PAM towards more quantitative and species-specific monitoring.
Results which will assist in the identification of important habitats, management of threats and which provide a knowledge base for future research and monitoring in the region.
Development of positive and effective relationships and collaborations between researchers, Indigenous rangers and regional wildlife management staff.
Protocol for vessel-based surveys to estimate dolphin abundance and distribution to be used by DBCA and Indigenous rangers

Project News:

Scientists learn more about Kimberley dolphin populations

Kimberley dolphin project covers new ground

Kimberley dolphins vulnerable to human activity

ABC TV News story by reporter Natalie Jones

Cone Bay proves reliable for acoustic recordings of humpback dolphins