The Western Pygmy Perch (Nannoperca vittata) is a small species (up to 8cm TL) of freshwater fish found only in the south-west of Western Australia. Within the south-west however the species is relatively widespread and abundant, found in lakes, streams, rivers & swamps. Despite this, the species still faces many threats, including climate change, secondary salinisation, and invasive species (the introduced Eastern Gambusia is known to fin-nip pygmy perch). Thankfully the ecosystem services this species provides (such as mosquito control) has been recognised and local councils and other groups are helping reintroduce the species into wetlands across the south-west. Despite these efforts, how much do we really know about the Western Pygmy Perch? And are we managing just one species, or are there actually several cryptic species? Research by Buckley et al. (2018) used genomic data and modelling techniques to explore how the pygmy perches of Australia have evolved, including how during Australia's less arid past the east and west coast were connected with waterways allowing the species to disperse. An unexpected find from this study however was that there may potentially be up to 3 distinct species/lineages within the traditionally recognised Western Pygmy Perch. To highlight why these may actually be distinct species, the authors documented that the level of divergence between these N. vittata lineages is similar to that between N. vittata and the Little Pygmy Perch (Nannoperca pygmaea). Now the Little Pygmy Perch itself was only discovered in 2009 and named in 2013; up until then it was likely being misidentified as the Western Pygmy Perch. Research since its identification has continued to increase the understanding of the species, including the discovery of new populations. If the Little Pygmy Perch went unnamed for so long, is it possible that there are in fact more distinct cryptic species in the south west? The region is already a hot-spot for endemism, with 9 of the 11 native freshwater fish found no where else. Should these numbers actually be 11 of 13? Only time and more solid scientific research with larger sample sizes etc. will tell. With the discovery of 20 new species in the Kimberley in the last few years, and now the potential for three more in the south-west it is an exciting time for freshwater fish science in Western Australia. Did you know? The Western Pygmy Perch can also be purchased for aquariums and ponds (like this little one we had in our home aquarium). They can co-inhabit ponds with frogs and are great at controlling mosquito larvae! Further reading & resources:
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AuthorMy name is Garry and I am extremely passionate about the environment. I have completed my BSc. Conservation and Wildlife Biology with First Class Honours and have worked in the Environment sector since 2009. Archives
September 2019
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Photos used under Creative Commons from sean.kelleher1, BioDivLibrary, BioDivLibrary