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Study uncovers northwest transition zone for Australian reef fish

30 October 2017

Stripey snapper (Lutjanus carponotatus)

Research has shown that a stretch of ocean surrounding the tip of the Dampier Peninsula, 200 kilometres north of Broome, acts as an invisible genetic barrier for a popular harvested tropical fish known as the stripey snapper.

The findings highlight the importance of the transition zone at the border of the Kimberley and Canning marine bioregions as a consideration for fisheries management. 

The barrier spans a 180 kilometre stretch of ocean at the southern border of the Kimberley bioregion that coincides with the mouth of King Sound, which experiences the largest tropical tidal range and fastest tidal currents in the world.

The collaborative project for the Western Australian Marine Science Institution’s Kimberley Marine Research Program, was led by Curtin University researcher Dr Joseph DiBattista and Department of Primary Industries and Regional Development’s Dr Michael Travers together with CSIRO’s Dr Oliver Berry. The results have been published in the international journal Molecular Ecology.

“These results are important for managing harvest of the stripey snapper (Lutjanus carponotatus), because we had assumed that they moved easily between the Pilbara and Kimberley regions, but it appears that they do not,” Dr DiBattista said.

“We know that the fish must rarely move between the Kimberley and Pilbara because they have strong genetic differences between those regions,” Dr Berry said.

 The researchers were surprised at how narrow the barrier was.

“The transition between fish that have the genetic fingerprints of the Pilbara and the genetic fingerprints of the Kimberley occurs over a very narrow region near the mouth of King Sound,” Dr Berry explained. “Fish that are found within this region are a mix, but outside of that region they are distinctive.”

“This study will improve management of this and potentially other reef fish species across northwestern Australia as it highlights the importance of the techniques used in this research to provide outcomes relevant to management, particularly for species with broad ranges such as the recreationally harvested stripey snapper,” Dr Travers said.

 

Map of sampling sites (yellow dots) for Lutjanus carponotatus across the entire sampling range in Northwestern Australia. The Holloway Current is the dominant current affecting coastal waters of the Kimberley, Canning, and Pilbara bioregions and the Leeuwin Current significantly impacts the Ningaloo and Shark Bay bioregions (adapted from Sprintall et al. 2002; Domingues et al. 2007; D'Adamo et al. 2009; Schiller 2011). Illustration of L. carponotatus © R.Swainston/www.anima.net.au.

 

It’s the first time that scientists have examined how far Kimberley marine animals and plants move.

The research also investigated movement in six other marine species including damselfish, corals, seagrasses and trochus shells.

The final results will be presented at the 2017 WAMSI Research Conference by project leader Dr Oliver Berry (CSIRO) in November.  

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The $30 million Kimberley Marine Research Program is funded through major investment supported by $12 million from the Western Australian government co-invested by the WAMSI partners and supported by the Traditional Owners of the Kimberley.

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Kimberley Marine Research Program