DISTRIBUTION AND CONSERVATION STATUS OF BLACKFISH 
101 
homogeneous substrates (Sanger 1990). Koehn 
(1987) found that boulders placed in the Ovens 
River markedly increased the numbers of G. bis- 
pinosus present because the boulders created a 
range of habitats that could be used as shelter 
from the fast water velocities. Being a smaller, 
more slightly built species than G. marmoratus 
(southern form), G. bispinosus appears to be able 
to utilize such instream niches more effectively. 
G. bispinosus was not found in the headwaters of 
many streams that, although providing sheltered 
areas, also contained areas of fast-flowing or cas¬ 
cading water. 
Several other freshwater fish genera include 
two closely related species, one of them inhabit¬ 
ing the upper reaches of a river system and the 
other inhabiting the lower reaches. The Murray 
cod, Maccullochella peeli , inhabits the warmer, 
slower, lowland reaches of streams in the Mur¬ 
ray Darling River system, whereas the trout cod, 
M. macquariensis , is better adapted to cooler 
upland reaches (McDonald 1978, Cadwallader 
1979, Cadwallader & Gooley 1984). The distri¬ 
butions of the golden perch, Macquaria cim- 
bigua , and the closely related Macquarie perch, 
M, australasica , show a similar relationship 
(McDonald 1978, Cadwallader 1979, 1981), as 
do the distributions of the flat-headed galaxias, 
Galaxias rostratus , and the Mountain galaxias, 
G. olidus , in the Murray-Darling River system 
(Cadwallader 1979, Cadwallader & Backhouse 
1983). 
Galaxias olidus was present at many of the 
Victorian localities surveyed and would be 
expected to occur throughout much of the range 
of G. bispinosus. The distribution and abund¬ 
ance of G. olidus has been severely reduced, 
however, by interactions with brown trout, S. 
trutta, and mutually exclusive populations of the 
two species have been documented (Tilzey 1976, 
Cadwallader 1979, Fletcher 1979, Jackson & 
Davies 1983, Jackson & Williams 1980. Koehn 
unpubl. data). Regular stocking of S. trutta by 
the Fisheries Division occurs throughout the 
range of G. bispinosus (Bamham 1989), and 
because the upper reaches of streams are par¬ 
ticularly suited to both species, interaction 
between them may be expected to be more 
intense than between G. marmoratus and S. 
trutta. Sanger (1984) noted predation by S. 
trutta as a cause of mortality in G. bispinosus but 
reported that G. bispinosus remained abundant. 
Jackson (1978a, 1981) and Jackson & Williams 
(1980) considered that, although there was 
dietary overlap between G. marmoratus and 
trutta , they avoided direct competition by 
occupying different habitats. 
The sympatric relationship between G. bispi¬ 
nosus and G. marmoratus and the interaction of 
the former with S. trutta are worthy of further 
study. Further information is also needed on the 
habitat and spawning requirements of G. bispi¬ 
nosus , as environmental degradation such as 
sedimentation and habitat alteration are likely 
to pose the greatest threat to the species. 
ACKNOWLEDGEMENTS 
I thank Alan Baxter, Peter Jackson, Sandy Mori- 
son and Barry Tunbridge for providing collec¬ 
tion details of Fisheries Division specimens; 
Tarmo Raadik for details of specimens at the 
Museum of Victoria; Tony Gill for identifica¬ 
tion of specimens at the Australian Museum, 
Sydney; Damien O’Mahony for identification of 
Fisheries Division specimens and collation of 
data; George Paras for angling records; Darwin 
Evans and Andrew Sanger for comments on the 
manuscript; and Damien O’Mahony, Bill 
O’Connor and John McKenzie for technical 
assistance. For discussion on the conservation 
status of G. bispinosus , I am grateful to Phillip 
Cadwallader, Peter Jackson, Andrew Sanger, 
Bill O’Connor and others who attended the 
review meeting at the Arthur Rylah Institute for 
Environmental Research on 12 August 1989. 
Word processing was completed by Judy Firman 
and Claudine Wallace and drafting by David 
Ryan. 
REFERENCES 
Anderson, J. R. & Morison, A. K., 1989. Environ¬ 
mental flow studies for the Wimmera River, 
Victoria. Part D. Fish populations — past, 
present and future. Conclusions and recom¬ 
mendations. Arthur Rylah Institute for Envi¬ 
ronmental Research Technical Report Series 
No. 76. Department of Conservation, Forests 
and Lands, Melbourne. 
Barnham, C., 1983. Report on the census of angling 
clubs 1983. Fisheries and Wildlife Division, 
Ministry for Conservation, Melbourne. 
Barnham, C., 1989. Summary of immediately avail¬ 
able records of non-indigenous and indigenous 
fish stockings in Victorian public waters 1871 
to 1988. Fisheries Information Report No. 2 
(Draft), Freshwater Fish Management Branch, 
Fisheries Division, Department of Conser¬ 
vation. Forests and Lands, Melbourne. 
Baxter, A. F., 1985. Trout Management Group fish 
population surveys, 1978-79; location of samp¬ 
ling sites and fish species caught. Arthur Rylah 
Institute for Environmental Research Techni- 
