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About the report
The report “An overview of the impacts of translocated native fish species in Australia” reviews current literature on the history of translocation of native fish in Australia including the species translocated, their estimated natural range prior to European settlement, and their current distribution. The review considers the environmental impacts at a genetic, species and ecosystem level, and the social and economic impacts. Included are chapters on the techniques for management of translocated native fish and current policies.
The report has been prepared for the Australian Government Department of the Environment, Water, Heritage and the Arts by Sinclair Knight Merz Pty Ltd and includes maps of estimated range and translocations.
Translocation of native species has been occurring to various extents throughout Australia since the time of European settlement. The definition of translocations varies across the literature and has historically been considered to be the intentional movement of species to an area outside their natural range. The definition of translocation which has been used in this report encompasses species that have been moved within and outside their natural range. The definition to be applied in this report is:
Translocation is the movement of living organisms from one area with free release in another (1999). This includes intentional and unintentional movement of individuals within and outside their natural range. This term includes introductions, re-introductions and re-stocking (IUCN 2000).
The definitions of the above terms are as outlined in IUCN (2000):
- Introduction means the movement, by human agency, of a species, subspecies, or lower taxon (including any part, gametes or propagule that might survive and subsequently reproduce) outside its natural range (past or present). This movement can be either within a country or between countries.
- Re-introduction means an attempt to establish a species in an area which was once part of its historical range, but from which it has been extirpated or become extinct. (From IUCN Guidelines for Re-Introductions)
- Re-stocking is the movement of numbers of plants or animals of a species with the intention of building up the number of individuals of that species in an original habitat (where the same species is already known to exist).
The species covered in this report are limited to translocated native fish species which spend all, or part of their life-cycle in freshwater systems as well as saline inland lakes and waterways. This includes translocations into natural and artificial waterbodies – but excludes the location of aquaculture facilities.
The movement of fish species beyond their natural range is potentially one of the most ecologically damaging of human activities (Koehn 2004a) and management of alien and translocated species may be one of the biggest challenges that conservation biologists face in coming decades (Harris and Battaglene 1990; Harris 2003; Lintermans 2004). The translocation of native species can have impacts upon indigenous populations of native fish, the general ecosystem into which translocations occur, as well as subsequent social and economic impacts over time (Morgan et al. 2004). The presence of fish outside their natural range can affect indigenous fish populations via predator-prey interactions as well as direct and indirect competition for food, habitat and resources.
The introduction of disease and parasites is also possible via translocated species from other regions and hybridisation potential exists if non-indigenous and indigenous species interbreed. This interbreeding can compromise the genetic integrity of native fish (Barlow et al. 1987; DPI 2005a).
The translocation of native species has been associated with the decline of some native fish species via predation. The abundance of Lake Eacham rainbowfish, (Melanotaenia eachamensis) in Lake Eacham Queensland has been significantly affected by the translocation of native species such as the mouth almighty (Glossamia aprion) being introduced into the lake prior to 1983 (Barlow et al. 1987; Leggett and Merrick 1997). At the time of the abovementioned studies, the Lake Eacham rainbowfish was thought to be endemic to Lake Eacham suggesting that the species may have been pushed toward extinction as a result of this translocation. It has since been identified to persist in the associated streams (Pusey et al. 1997).
Human-mediated movement of fish has a long history in Australia with both alien and native species moved since the mid 1800s (Clements 1988). The reasons and/or mechanisms for moving fish within and between drainages are many and varied. Prior to 1940, translocations in NSW have been performed for the purposes of stock enhancement for fisheries and by acclimatisation societies (DPI 2005a). Similar activities were conducted in other States, particularly in eastern and southern Australia. For example, common species, including the large-bodied native species Murray cod, (Maccullochella peelii peelii) and golden perch (Macquaria ambigua), have both been legally and illegally stocked for the purpose of enhancing fisheries (Lintermans 2004).
Water diversions and transfers have led to translocations of native species in Australia. A drastic example of this in Tasmania was the flooding of Lake Pedder as a hydro electric storage. This inundation allowed the translocation through natural dispersal of climbing galaxias (Galaxias brevipinnis) into the home range of the endemic species, Pedder galaxias (Galaxias pedderensis). The competition for habitat from climbing galaxias combined with the introduction and predation from brown trout (Salmo trutta) has driven the Pedder galaxias to the point of extinction in the wild (Sanger 2001). In order to save the Pedder galaxias from extinction, a founder population was translocated into a small natural lake south of Lake Pedder (Sanger 2001). This example highlights the means by which translocation of native species can also be employed as a tool for the conservation of threatened species. Further, the Midgley's carp gudgeon (Hypseleotris sp. 1), an established translocated species in the River Torrens South Australia, could have been introduced via a number of pathways including inter-basin transfer of Murray water into the catchment (also with fingerlings of angling species, aquarium escapees, etc) (M. Hammer, pers. comm.).
Escape from professional and amateur freshwater aquaculture facilities has been suggested as a means for native species to be translocated outside their natural range. Freshwater aquaculture escapes of silver perch (Bidyanus bidyanus) have recently been recorded in Western Australia (Cross 2000).
Galaxiid species have also been moved outside their natural range. Golden galaxias (Galaxias auratus) became established in Lake Crescent as a result of invasion from Lake Sorell, in Central Tasmania via a man-made channel (Allen et al. 2002). There have been anecdotal reports of translocated populations of spotted galaxias (Galaxias truttaceus) north of the Great Dividing Range in the Loddon and Campaspe River systems, central Victoria since at least the early to mid 1980’s (G. Closs, University of Otago, pers. comm.). Climbing galaxias have also been translocated into the Murray River via transfers from the Snowy Mountain hydro electric scheme (Waters et al. 2002).
The translocation of native species has had significant social and economic impacts. Translocation has created viable recreational fisheries in many areas where the indigenous native fish fauna are generally small bodied species. There are a number of successful fisheries in Australia which are based upon non-indigenous natives such as the translocated species of golden perch (Macquaria ambigua) in the Wimmera River, western Victoria. Native fish such as barramundi (Lates calcarifer) have also been successfully farmed in freshwater aquaculture schemes outside their natural distribution providing economic benefits.