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.
Rapid soil development in response to land use change: case studies from the northern New South Wales slopes, plains and New England Tablelands