DARLING RIVERINE PLAINS BIOREGION Background Report

16/08/02 Darling Riverine Plains Bioregion Background Report
Table 6.3 Introduced fish species recorded within the Barwon-Darling Region
(Harris & Gehrke 1997; Harris 1995)
Family Scientific Name Common Name Catchment Recorded
Atherinidae Carassius auratus goldfish G, N, C, M, D, B-D
Cyprinidae Cyprinus carpio European carp G, N, C, M, D, B-D
Percidae Perca fluviatilis redfin perch G, M, D, B-D
Poeciliidae Gambusia holbrooki gambusia G, N, C, M, D, B-D
Salmonidae Oncorhynchus mykiss rainbow trout M
Salmonidae Salmo trutta brown trout M
Salmonidae Salvelinus fontinalis brook trout M
Cyprinidae Tinca tinca tench B-D
Key
G = Gwydir River Catchment M = Macquarie River Catchment
N = Namoi River Catchment D = Darling River Catchment
C = Castlereagh River Catchment B-D = Barwon Darling River
Gambusia
Gambusia holbrooki have been implicated in the decline in abundance or range of 35 fish
species world-wide, and there is circumstantial evidence that several Australian native fish
species have been adversely affected by the spread of this species. Predation by Gambusia has
been listed as a key threatening process under the TSC Act, primarily because of predation of
tadpoles and eggs of some frog species in eastern New South Wales. The impact of Gambusia
on native fish species occurs through a variety of mechanisms including direct competition
for resources, interference, competition and predation. The species is an adaptable generalist
predator, which feeds on a wide range of both terrestrial and aquatic organisms (Harris &
Gehrke 1997).
European carp
Numbers of European carp increased greatly in the Macquarie and Bogan River system in the
mid-1970s, assisted by the floods of 1974 and 1975 (Macquarie 2100 plan 1999). It has been
estimated that European carp make up 50% of the total biomass in the river. European carp
damage the river habitat by increasing water turbidity, decreasing water plant diversity and
abundance, increasing water nutrients, increasing algal concentrations by preying on
zooplankton, reducing native fish numbers, decreasing small insect numbers and eroding
stream banks (King 1995). European carp are the dominant fish species of the Murray-
Darling system. Their abundance is demonstrated at one site in the lower reaches of the
Bogan River, where there was an average of one European carp per square metre of river
surface area. Flow regulation has allowed the development of suitable habitat for European
carp while promoting the destruction of suitable habitat for the less sedentary native species
(Harris & Gehrke 1997).
117