Species at risk: Stocky galaxias

Feb 20, 2019 | Species at risk: Wildlife

Stocky galaxias © State of New South Wales through NSW Department of Industry.

Stocky galaxias © Tarmo A. Raadik

 

Stocky galaxias

Galaxias tantangara
Critically Endangered – Fisheries Management Act 1994

Just a single population of stocky galaxias is known to exist in Kosciuszko National Park. The larger distribution of this native fish species fell victim to the introduction of predatory feral trout.

A large population of feral horses has established well-worn trails across and around the creek habitat of the remaining stocky galaxias population. Horse trampling has resulted in an almost complete loss of vegetation, leading to stream bank erosion that has created wide, shallow, murky segments where the fish cannot live.

Downstream of horse crossings fine sediment dislodged by horse damage has built up from pugging, trampling, bank slumping and runoff from trails. This sediment accumulation is less severe or absent immediately upstream of crossings.

Rocky surfaces and clean spaces between stones are important for stocky galaxias to reproduce. Sedimentation reduces the availability of spawning habitat and smothers and kills fish eggs. Direct damage by horse trampling could also crush eggs and larvae.

The population density of horses in Northern Kosciuszko is two to three times the density recorded elsewhere in the Australian Alps. For the survival of this critically endangered species, it is integral for horses to be removed from their habitat.

 

References

  • Cairns, S. and Robertson, G. (2015) 2014 Survey of Feral Horses (Equus ferus caballus) in the Australian Alps. Australian Alps Liaison Committee, Canberra
  • Cowden, K. (1988) Aspects of Biology of the Mountain Galaxiid, Galaxias olidus Gunther (Pisces: Galaxiidae) in Pierces Creek ACT. BSc (Hons) thesis, The Australian National University, Canberra.
  • Allan, H., Linterman, M., Worboys, G. L., Driscoll, D. and Crabb, P. (2018) Fish: impacts of feral horses —Stocky Galaxias, Feral Horse Impacts: The Kosciuszko Science Conference – Conference Abstracts, Australian Academy of Science, The Australian National University, Deakin University, Institute for Applied Ecology University of Canberra.
  • NSW FSC (NSW Fisheries Scientific Committee) (2016) Final Determination: Galaxias tantangara – Stocky Galaxias as a Critically Endangered Species. NSW Fisheries Scientific Committee, Sydney.
  • Raadik, T. A. (2014) Fifteen from One: A Revision of the Galaxias olidus Günther, 1866 Complex (Teleostei, Galaxiidae) in South-eastern Australia Recognises Three Previously Described Taxa and Describes 12 New Species. Zootaxa 3898: 1–198.
  • Stoessel, D. J., Raadik, T. A. and Ayres, R. M. (2015) Spawning of Threatened Barred Galaxias, Galaxias fuscus (Teleostei: Galaxiidae). Proceedings of the Linnean Society of New South Wales 137: 1–6.