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Freshwater fish and crayfish communities of the Carbunup and Buayanyup Rivers: conservation significance and management considerations

Beatty, S., Morgan, D. and Allen, M. (2009) Freshwater fish and crayfish communities of the Carbunup and Buayanyup Rivers: conservation significance and management considerations. Murdoch University. Centre for Fish & Fisheries Research, Western Australia.

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    Abstract

    This study is the first to examine the fish and freshwater crayfish of the Carbunup and Buayanyup Rivers, south-western Australia. It aimed to determine the distribution of the fishes and freshwater crayfishes, their conservation significance and management implications to help ensure the ongoing viability of these communities.

    Ten sites each in the Carbunup and Buayanyup Rivers were sampled for fish and freshwater crayfish in November 2008.

    Carbunup River

    Contained four of the eight endemic species of freshwater fishes of the south-west region, including the rare (Schedule 1 Wildlife Protection Act 1950) Mud Minnow.

    The Gilgie was the most widespread crayfish species and limited numbers of the Smooth Marron were also captured.

    All populations appeared viable based on abundances, distributions and population structures; however, the viability status of the Mud Minnow and Smooth Marron requires further investigation.

    The estuarine site at the mouth of the Carbunup River was found to house nine species of fish and two decapods; including Black Bream, Sea Mullet and Blue Swimmer Crabs.

    The estuarine habitat of the river probably provides nursery and/or spawning habitats for a number of estuarine and nearshore marine species.

    The introduced Eastern Gambusia was the only introduced species recorded in the Carbunup River (although historical reports of the Redfin Perch also exist for the system). The dry season abundance and distribution of Eastern Gambusia should be assessed to better understand its impact on native fishes in the system.

    Buayanyup River

    Contained four endemic fishes; including the restricted Black-stripe Minnow. The identification of the species requires final confirmation by examination of a greater number of (larger) specimens or genetic analysis and, if confirmed, would represent a considerable range extension of the species.
    Three native freshwater crayfishes were recorded with the Gilgie again being widespread and abundant whereas the Smooth Marron and Koonac were recorded in low numbers and had more restricted distributions.
    Twelve fish and one shrimp species were recorded at the estuarine site in Buayanyup Brook; including Black Bream, Australian Salmon and Sea Mullet. As with the Carbunup.

    River, the tidal reach of Buayanyup probably provides nursery and/or spawning habitat for a number of estuarine and nearshore marine species.

    Both the introduced Yabbie and Eastern Gambusia were recorded in Buayanyup River with control programs of the species potentially able to reduce abundances and restrict their spread; but would be unlikely to completely eliminate them from the river.

    The widespread and abundant Western Pygmy Perch in Buayanyup River would be an ideal species for the proposed captive breeding program at the Naturaliste College. This species is a successful aquarium species and, if adequate habitat, food resources and water quality are provided, should be able to be successfully bred by the students.

    Future actions
    Additional surveys should be undertaken to determine the distribution and viability of the Mud Minnow and Black-stripe Minnow (as well as its final identification) in the Carbunup and Buayanyup River, respectively.

    Additional, dry-season surveys of the distribution and abundances of Eastern Gambusia and Yabbie should be conducted with the aim of potentially developing control programs for these species.

    Greater understanding of the estuarine fish communities of both systems could be achieved by undertaking seasonal sampling in the lower reaches of these rivers.

    Protection and rehabilitation of riparian and instream vegetation via River Action Plan development for these systems would enhance the long-term viability of the prevailing native fish and freshwater crayfish communities via: helping to maintain and increase water quality, supplying shelter from predators, creating spawning habitat and supplying food resources.

    Publication Type: Report
    Murdoch Affiliation: Centre for Fish and Fisheries Research
    Series Name: Technical report to Geocatch
    Publisher: Murdoch University. Centre for Fish & Fisheries Research
    Copyright: 2009 Murdoch University. Centre for Fish & Fisheries Research
    Publishers Website: http://www.geocatch.asn.au/
    URI: http://researchrepository.murdoch.edu.au/id/eprint/5986
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