Lowland Riverine Fish Community of the Southern Murray-Darling Basin

Advice to the Minister for Environment and Heritage from the Threatened Species Scientific Committee (TSSC) on an Amendment to the List of Threatened Ecological Communities under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)

1. Name

Lowland Riverine Fish Community of the Southern Murray-Darling Basin.

2. National Context

The nominator described this ecological community as occurring in the lowland reaches and associated floodplains of the Murray, Darling and Murrumbidgee rivers and their tributaries within the States of Victoria, New South Wales and South Australia. The nominator suggested that 'lowland' refers to areas < 700 m asl.

The nominator maintains that although the current distribution and abundance of fish in the Murray and Darling river systems differs, this reflects the varying impacts of threatening processes rather than natural differences in the historical range of the fish taxa. The nominator contends that at the national scale it is essentially the same community.

3. Description

The ecological community occurs in the lowland reaches and associated floodplains of the Murray, Darling and Murrumbidgee rivers and their tributaries within the States of Victoria, New South Wales and South Australia. The exact geographic extent of the ecological community is not clear and there is no consensus by the experts as to how best identify the boundaries.

The nominator used the following fish species to define the ecological community:

No. Scientific name Common name
1. Maccullochella macquariensis Trout cod
2. Macquaria australasica Macquarie perch
3. Craterocephalus fluviatilis Murray Hardyhead
4. Ambassis agassizii Agassiz's Chanda Perch
5. Bidyanus bidyanus Silver Perch
6. Craterocephalus stercusmuscarum fulvus Non-specked Hardyhead
7. Galaxias rostratus Flat-headed Galaxias
8. Hypseleotris klunzingeri Western Carp Gudgeon
9. Maccullochella peelii peelii Murray Cod
10. Macquaria ambigua Golden Perch
11. Melanotaenia fluviatilis Murray Rainbow Fish
12. Mogurnda adspersa Southern Purple-spotted Gudgeon
13. Nematoalosa erebi Bony Bream
14. Philypnodon grandiceps Flat-headed Gudgeon
15. Tandanus tandanus

Freshwater Catfish

Many of these species have declined in abundance and distribution and some are listed as threatened on various States and Commonwealth legislation.

However, a number of the species also occur outside the proposed area and the nomination fails to include others that may be suitable for inclusion within the definition. In addition, it does not include other taxa (such as invertebrates and plants) that may legitimately be considered as part of the ecological community.

4. How judged by TSSC in relation to the EPBC Act criteria.

The TSSC judges that the ecological community is not adequately defined with regard to the species composition and its geographical extent. Consequently, its conservation status cannot be assessed against the criteria.

Particular issues include:

  • Defining the ecological community: the nomination describes the ecological community as comprising 15 fish species. There is little justification as to why the ecological community should be confined to only these species and exclude other fauna and flora.
  • Although the nominator maintained that the fish that define the community are those that have their geographic distribution wholly within the defined area, a number of the species are found elsewhere. In addition, a number of fish species are not included in the definition that may be considered as part of the ecological community.
  • The description of the ecological community is not sufficient to identify it in the field or to distinguish it from other ecological communities.
  • Information on the conservation status of the proposed ecological community has not been considered at a National scale. In particular, very little information has been provided with regard to the conservation status of the ecological community in South Australia.
  • The geographic location, or boundaries, of the ecological community is not adequately defined. The nominator and some experts suggested restricting the area to the Murray-Darling river system below 700 m. However, other experts maintained that this was inappropriate as it included areas that could not be considered 'lowland'.
  • There was no consensus from experts with regard to how the ecological community could be more accurately defined, both with regard to species composition and location.

5. Conclusion

The TSSC conclude that the ecological community "Lowland Riverine Fish Community of the Southern Murray-Darling Basin" cannot be accurately defined, both with regard to the species composition and geographic extent. As a consequence it is not possible to assess the extent to which the ecological community meets the criteria for listing ecological communities under the EPBC Act.

Based on the report Threatened and Potentially Threatened Freshwater Fishes of Coastal New South Wales and the Murray Darling Basin and information provided by experts, the TSSC conclude that in addition to the fish species currently listed under the EPBC Act, a number of others may also be threatened nationally and thus, may be eligible for listing under the EPBC Act. However, there is insufficient information in the nomination to establish a case for listing these species individually.

6. Recommendation

TSSC recommends that the ecological community "Lowland Riverine Fish Community of the Southern Murray-Darling Basin" is not eligible for inclusion in the Endangered category of the list referred to in section 181 of the EPBC Act