Riverine fish in New South Wales were studied
to examine longitudinal trends in species richness and to identify fish
communities on a large spatial scale. Five replicate rivers of four types
(montane, slopes, regulated lowland and unregulated lowland) were selected
from North Coast, South Coast, Murray and Darling regions. Fishwere sampled
during summer and winter in two consecutive years with standardized gear that
maximized the range of species caught.
The composition of fish communities varied among regions and river types, with
little temporal variation. Distinct regional communities converged in montane
reaches and diverged downstream. The fish fauna can be classified into North
Coast, South Coast, Murray and Darling communities, with a distinct montane
community at high elevations irrespective of the drainage division. Species
richness increased downstream in both North Coast and South Coast regions by
both replacement and the addition of new species. In contrast, species
richness in the Darling and Murray regions reached a maximum in the slopes
reaches and then declined, reflecting a loss of species in lowland reaches.
The small number of species is typical of the freshwater fish faunas of
similar climatic regions world-wide. Fish communities identified in this study
form logical entities for fisheries management consistent with the
ecosystem-focused, catchment-based approach to river management and water
reform being adopted in Australia.
