30 
J. D. KOEHN & W. G. O’CONNOR 
have mean daily flows of 745 ML and 714 ML 
respectively (State Rivers & Water Supply Com¬ 
mission 1984). Both rivers have weirs on their 
upper reaches and have been the subject of 
stream-flow studies which provide recom¬ 
mended flow rates to maintain fish populations 
(Tunbridge & Glenane 1988, Tunbridge 1988). 
Both rivers have their headwaters in forested 
catchments but flow mostly through farmland. 
The lower reaches of the Barwon River flow 
through urban areas of the city of Geelong. 
The Aire River system west of Cape Otway is 
the third largest waterway in the Otway region, 
the main river having a length of 40 km and a 
mean daily flow of 174 ML (State Rivers & 
Water Supply Commission 1984). Watercourses 
draining the main ridge east of Cape Otway are 
primarily short, fast-flowing streams emptying 
into the Southern Ocean. Many of these streams 
flow for less than 10 km and have mean flow 
rates of less than 60 ML per day. Many of them 
flow through forested catchments which remain 
in a relatively natural condition. Waterfalls are 
common on the coastal streams and often form 
natural barriers to fish passage. 
Waters in the Otway region have been stocked 
with salmonids from as early as 1879, initially by 
the Geelong and Western District Fish Acclim¬ 
atisation Society and later by Victorian Govern¬ 
ment departments (Barnham 1989). Most 
streams were stocked with brown trout, Saltno 
trutta, but rainbow trout, Oncorhynchus my kiss, 
were also released until 1968 at a smaller num¬ 
ber of sites, including the West Barwon Dam and 
the lower reaches of the Barwon River (Wharton 
1969). Only the Aire. Barham, Barwon, Ford, 
Gellibrand and St Georges (Reservoir Allen¬ 
dale) Rivers have been stocked with brown trout 
since 1970 (Barnham 1989). Between 1982 and 
1986 the Barwon River was the only river 
stocked, receiving between 3000 and 5000 
brown trout annually (Hume & Barnham 
1986). 
METHODS 
The location of each site sampled is shown in 
Fig. 1. Map grid references for each site 
(obtained from 1:100,000 maps of the Topo¬ 
graphic Survey National Map Series) as well as 
the names of streams and the dates and method 
of sampling are given in the Appendix. 
A Smith Root MK VIA bank-mounted elec¬ 
trofisher (Koehn & McKenzie 1985) was used to 
sample fish at 52 sites. Jackson & Williams 
(1980) sampled site 20 by electrofishing in 1974 . 
Rotenone was used by McCarraher (1 986) at site 
4 in 1977 and 1981, and by Baxter (1985) to col¬ 
lect spotted galaxias and Australian grayling at 
site 26 on 1 March 1982. A dip net was used to 
sample whitebait at site numbers 6,7,11,14, lg, 
21 , 25, 30, 33, 42 and 45 (Appendix). Two sites 
were also sampled overnight as follows: 
Sites 36 and 37: 4 single winged fyke nets(13 
mm mesh) 
Site 37: 25 mm, 50 mm, 75 mm, 88 mm, 100 
mm and 125 mm mesh nets, each 25 m long. 
Electrofishing was considered to be efficient 
at all sites (see Koehn & McKenzie 1985) for all 
species except lamprey ammocoetes which often 
avoided capture by burrowing. Dip net sampling 
for whitebait of the common galaxias at site 45 
was not considered efficient for other species. 
Fish were identified in the field using Cad- 
wallader & Backhouse (1983). If identification 
was uncertain, specimens were preserved in 10% 
formalin for later examination. The collections 
of the Museum of Victoria were checked for all 
fish species with localities in the Otway region. 
RESULTS 
Eighteen species of freshwater fish, 14 of them 
native and 4 introduced, have been recorded in 
the Otway region (Table 1). Species recorded at 
each site are listed in the Appendix, Species such 
as the small-mouthed hardyhead (Atherimom 
microstoma ), Tamar River goby (Famigobm 
tamarensis ) and blue-spot goby (Pseudogob'w 
olorum) occur in the estuarine reaches of many 
of the coastal streams (Cadvvallader & Back¬ 
house 1983, Tunbridge & Glenane 1983) but 
were not encountered during our survey. Simi¬ 
larly, the mainly estuarine flat-headed gudgeon 
(Philypnodon grandiceps) is expected to be more 
widespread than our results suggest. 
The short-finned eel was the most widespread 
species, occurring at 49 sites. Species of galaxias 
were also widespread and often abundant, but 
only one specimen of the Tasmanian mudfish 
was found (at site 17). Australian grayling were 
caught at nine sites, but usually as juveniles and 
usually fewer than 10 in number. Juvenile gray¬ 
ling were captured in the lower reaches of the 
Cumberland River (Site 14) on 25 February 
1987 and whitebait of this species were captured 
ascending the stream on 24 November 198/. 
Tupong were generally caught only in the lower 
reaches of streams. At site 14 tupong were found 
only below a roadway pipe in which water vel- 
