The Donnelly River catchment: an important refuge for all of south-western Australia's endemic freshwater fishes and the Pouched Lamprey (Geotria australis)

The fish fauna of the Donnelly River is described from historical published and unpublished data and from captures during 2006. The Donnelly River catchment is one of only two river systems that contain all of south-western Australia's eight endemic freshwater fish species. The high diversity of fishes in the Donnelly River catchment, including Lake Jasper, Lake Wilson and Lake Smith, is likely to be due to the heterogeneity of aquatic habitats in the system. For example, species such as the Salamander fish and Black-stripe Minnow are restricted to ephemeral pools and floodplain environments on Scott Rd and around Lake Smith. Lake Smith is also the only known location within the catchment of the rare Balston's Pygmy Perch and, together with Lake Wilson, is the only known habitat in the catchment of the large Freshwater Cobbler. The Western Minnow, Western Pygmy Perch and Nightfish were relatively common and widespread through the catchment; occurring in most habitat types. The rare Western Mud Minnow is restricted to headwater streams and is very uncommon in the system, in part possibly due to predation by exotic species. It is also one of the few systems that provide extensive habitats for the adult and larval stages of the Pouched Lamprey. Three introduced fishes are known from the Donnelly River, the Eastern Mosquitofish, Redfin Perch and Rainbow Trout, the latter being the most widespread; presumably as a consequence of the long term stocking of the species into the catchment. Despite the presence of these introduced species, the Donnelly River should be considered of high conservation importance due to its south-western endemic fish populations