DARLING RIVERINE PLAINS BIOREGION Background Report

More documents

Recommendations

Info

16/08/02 Darling Riverine Plains Bioregion Background Report movements varies between species: the migratory species Macquaria ambigua and Bidyanus bidyanus (silver perch) can travel the length of the Murray-Darling system, while some small species such as hardyheads and gudgeons require only a few kilometres of river to complete their life cycle. Obstruction of migratory movements can lead to the extinction of populations and species and this problem requires large scale change to river management to be effective (Harris 1995). The NSW Rivers survey found that there were proportionally more native species than introduced species in unregulated rivers and 13 native fish species showed a negative response to river regulation (Harris & Gehrke 1997). The severity of the decline in fish diversity and abundance in this system has not been fully documented, although some significant falls have been documented in catches of Maccullochella peelii, Tandanus tandanus and the near disappearance of Bidyanus bidyanus from the Darling. Overall, in New South Wales rivers 62% of native fish have undergone reductions in range and/or abundance, suggesting that they are more vulnerable to disturbance than was previously thought. Maccullochella peelii has undergone a significant reduction in range and abundance and is now relatively uncommon in many areas (Harris & Gehrke 1997). 6.2.3 Regionally endemic species and significant populations Two significant populations of fish have been identified as occurring in the DRP. The population of Mogurnda adspersa in western New South Wales has been listed as an endangered population under the FMA 1994. This species was once widespread throughout the Murray-Darling system and in coastal streams. The eastern population now occurs in coastal drainages north of the Clarence River, but its distribution throughout the Murray- Darling system is very limited and has significantly declined in recent years. There has been only a single record of this species in the Murray-Darling since 1983. These eastern and western populations may be genetically distinct. The causes of the decline of the western populations of this species are thought to include predation by Gambusia holbrooki and Perca fluviatilis, habitat loss and rapid fluctuations in water levels as a result of water regulation, which affects reproduction and recruitment (FSC 2001e). The Fisheries Scientific Committee has also listed the western population of Ambassis agassizii as an endangered population under the FMA 1994. This population has declined seriously in recent decades and is now possibly absent from the majority of Murray-Darling waterways (FSC 2001e). Regionally endemic species include Gadopsis bispinosus (two-spined blackfish), Galaxias rostratus, Melanotaenia fluviatilis (Australian rainbowfish), Maccullochella peelii and Bidyanus bidyanus (Morton et al. 1995). 6.2.4 Introduced fish species Of all rivers within NSW, the Darling River catchment contains the greatest diversity of introduced species, with six being present. These species are Cyprinus carpio, Carassius auratus (goldfish), Gambusia holbrooki, Perca fluviatilis, Oncorhynchus mykiss (rainbow trout) and Salmo trutta (brown trout). The two trout species and Perca fluviatilis are probably not present in the DRP bioregion, preferring the higher reaches of the Darling tributaries. Introduced species represented 25.1% of the total fish catch in the Darling system (Harris and Gehrke 1997). 116
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
Page 1 and 2:
DARLING RIVERINE PLAINS BIOREGION B
Page 3 and 4:
For more information data contact t
Page 5 and 6:
3.2 Vegetation Mapping and Descript
Page 7 and 8:
10 APPENDICES 166 A CLIMATIC DATA B
Page 9 and 10:
List of Maps Chapter 1 Map 1 Locati
Page 11 and 12:
PROJECT SUMMARY This report forms p
Page 13 and 14:
abbits are listed as key threatenin
Page 15 and 16:
16/08/02 Darling Riverine Plains Bi
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
ainfall (mm) 900 800 700 600 500 40
Page 33 and 34:
Page 35 and 36:
1500 1000 500 0 -500 -1000 -1500 -2
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66: 16/08/02 Darling Riverine Plains Bi
Page 115: 16/08/02 Darling Riverine Plains Bi
Page 133 and 134: Initial Phase Assessment Phase 16/0
Page 167 and 168:
Appendix A: Mean Monthly Rainfall a
Page 169 and 170:
80 70 60 50 40 30 20 10 0 25 20 15
Page 171 and 172:
Major Rangetype Rangetype Physiogra
Page 173 and 174:
Appendix C : Native Flora Other Tha
Page 175 and 176:
Family Scientific Name Common Name
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Family Scientific Name cretica Comm
Page 205 and 206:
Page 207 and 208:
APPENDIX E: Fauna Other than Those
Page 209 and 210:
Common Name Scientific Name No Reco
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Common 1983 1984 1985 1986 1987 198
Page 219 and 220:
Common Name 1983 1984 1985 1986 198
Page 221 and 222:
Taxa No Records Dataset Class Arach
Page 223 and 224:
Taxa No Records Dataset Family Hebr
Page 225 and 226:
Taxa No Records Dataset Tabanidae s
Page 227:
Taxa No Records Dataset Berosus sp
show all

DARLING RIVERINE PLAINS BIOREGION Background Report

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?