Fish and freshwater crayfish communities of the Brunswick and Preston Rivers

Abstract

The Leschenault Inlet, located on the Swan Coastal Plain near Bunbury, is the estuary of the Brunswick, Collie, Preston and Ferguson Rivers. There is a considerable amount of information detailing the fish fauna of the Leschenault Inlet with Potter et al. (1997, 2000) recording 42 species of fish from 26 families. The estuary is dominated by gobies, atherinids and clupeids which comprised almost 90% of the fishes. Potter et al. (2000) also reported 13 species from gill net captures in the lower (tidal) Collie River. Neither of these studies reported on the fishes found within the freshwaters of the Leschenault Inlet catchment and although Pen & Potter (1990, 1991a, b, c, d, 1992) conducted biological studies on a number of native and introduced freshwater fishes in the upper Collie River by, there is no published information regarding the prevailing fishes (or freshwater crayfishes) of the Brunswick or Preston Rivers. Hale et al. (2000) reported on the fish fauna of one site in the upper Brunswick River, near the confluence with the Augustus River, one site in the Augustus River and two sites in the Ernest River. While they recorded only two species of freshwater fish from the Ernest River (i.e. Western Pygmy Perch (Edelia vittata) and Nightfish (Bostockia porosa)), they captured a further two endemic freshwater fishes from the Augustus and upper Brunswick Rivers (i.e. Western Minnow (Galaxias occidentalis) and Freshwater Cobbler (Tandanus bostocki)) as well as larval (ammocoetes) Pouched Lampreys (Geotria australis) and three introduced fishes (i.e. Rainbow Trout (Oncorhynchus mykiss), Brown Trout (Salmo trutta) and Eastern Mosquitofish (Gambusia holbrooki)). The presence of the larger introduced fishes, the lamprey and the Freshwater Cobbler in the Augustus River compared to the Ernest River was attributed to the provision of environmental water releases from Freshwater Lake. These species are more often associated with permanent waters over ephemeral systems. The distributions of fishes inhabiting the inland waters of the south-western corner of Western Australia were documented in Morgan et al. (1998) and include the systems from Capel to Two People’s Bay east of Albany and thus does not encompass the more northerly Leschenault catchments, but does include some sites on the Collie River South Branch. The aims of the present study were to ameliorate the paucity of knowledge of the fishes and freshwater crayfishes inhabiting two of the major systems flowing into the Leschenault Inlet and thereby provide the Leschenault Catchment Council with an overview of the fishes of the Brunswick and Preston Rivers