Koehn, J.D., O'Connor, W.G. (Arthur Rylah Institute for Environmental Research);

The distribution of freshwater fishes in the Otway region of southwestern Victoria was determined with 18 species being recorded. Distribution of native fish appears to be related to geomorphological conditions existing during and after the last glaciation 20000-5000 years ago. The short coastal streams east of Cape Otway may have formed after the Bass Strait land bridge was submerged, or may have been subjected to dessication during an ensuing drier period. The native fish found of these streams consists of species with marine phases in their life cycles and may have originated by recolonization from the sea. Although species with entirely freshwater life cycles are absent from these streams, they are abundant in the Barwon, Aire and Gellibrand River systems suggesting that these systems were less affected by geomorphological conditions due to their much greater size or to their location.

Australian grayling were collected from nine sites in the Otway coastal streams, and valuable populations of freshwater blackfish and of several species of Galaxiidac were also recorded. The discovery of a Tasmanian mudfish in Wye River provides a second location for this species in Victoria, and whitebait of Australian grayling were recorded from the Cumberland River. Brown trout were found to be widespread but other introduced species were rare in the coastal streams. The freshwater fish faunas of the Otway region and of northern Tasmania are compared. The importance of the Otway region in the conservation of native freshwater fish species is discussed and careful management is recommended.