Survival ofSalmo gairdneri (rainbow trout) in the zinc polluted Molonglo River near Captains Flat, New South Wales, Australia

1986 ◽  
Vol 36 (1) ◽  
pp. 186-191 ◽  
Author(s):  
G. A. Graham ◽  
G. Byron ◽  
R. H. Norris
1981 ◽  
Vol 32 (6) ◽  
pp. 967 ◽  
Author(s):  
RWJ Pidgeon

The diets and growth rates of rainbow trout in the Wollomombi and Guy Fawkes Rivers in northern New South Wales were examined. The growth rate of trout in the Wollomombi River was much higher than that of fish in the Guy Fawkes River. Spearman rank correlation coefficients indicated that stream type was more important than fish size in determining the composition of the diet of the trout. Benthic invertebrates formed the largest component of the diet in both streams: 66.0 and 63.0% of ash-free dry weight (AFDW) in the Wollomombi River and the Guy Fawkes River, respectively. Trout in the Wollomombi River consumed more nektonic prey (33.3% of AFDW) than fish in the Guy Fawkes River (3.7% of AFDW). In contrast, surface food (aquatic imagines and terrestrial insects) made up a much higher proportion of the diet of trout in the Guy Fawkes River (33.9% of AFDW) than in the Wollomombi River (0.6% of AFDW). Crayfish were a major component of the diet (in terms of AFDW) in both streams, their proportions increasing with fish size. The significance of crayfish in relation to fish growth is discussed.


1983 ◽  
Vol 34 (3) ◽  
pp. 407 ◽  
Author(s):  
RA Faragher

The freshwater crayfish C. destructor was a major dietary item for brown trout, Salmo trutta L., and rainbow trout, S. gairdneri Richardson, in Lake Eucumbene, New South Wales. The incidence of crayfish in the diet increased, particularly in brown trout, over the period 1972-1977. The proportion of the trout's diet comprising C. destructor increased with length of brown trout but not with length of rainbow trout. The size of crayfish ingested was postively correlated with fish length for both species of trout, although rainbow trout tended to ingest smaller crayfish than brown trout of equivalent size. Analysis of the crayfish's diet revealed predominantly plant material. Spawning by the crayfish was apparently confined to the period December-April. The abundance of C. destructor in Lake Eucumbene was apparently low until about 1970 but increased between 1972-1977. A decline in the average size of brown and rainbow trout in the angler catch occurred from 1959-1960 until 1977-1978. Hypotheses are suggested for the increase of the crayfish population since impoundment of the lake (1957). Factors considered include predation by trout and the biology of the crayfish, particularly related to its occurrence in this lake, which has fluctuating water levels and a short season suitable for growth and spawning.


1992 ◽  
Vol 43 (4) ◽  
pp. 835 ◽  
Author(s):  
RA Faragher ◽  
GNG Gordon

Exploitation rates of syrnpatric brown trout and rainbow trout in Lake Eucumbene, New South Wales, were estimated from a tagging study. Tag returns were analysed by applying a non-linear regression method. Tag loss was estimated from a concurrent double tagging study using a maximum likelihood method. No significant difference at the 5% level was found between the rates of tag loss of the two species. The annual exploitation rate for rainbow trout was 26.7% (95% confidence interval 24.2- 29.2%) and was significantly less for brown trout, 8.8% (95% confidence interval 4.2-13.5%).


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