Galaxias pedderensis (Pedder Galaxias)

1. Scientific name, common name (where appropriate), major taxon group

Galaxias pedderensis (Pedder Galaxias)

2. Description

The Pedder Galaxias is a fish that has a slender elongated body and is a medium to large galaxiid species, typically growing between 75-120mm in length. The colour of the upper body and sides are a light grey-brown with irregular dark blotches. Iridescent gold flecks are also often present. The underside of the fish is grey-white and the fins are yellow-brown. As with all galaxias, there are no scales present. Pedder Galaxias feed primarily upon terrestrial and aquatic insects, as well as crustaceans.

3. National context

The Pedder Galaxias is endemic to southwest Tasmania, specifically the original Lake Pedder and associated tributary streams. However, in 1972 Lake Pedder and surrounding areas were inundated as a result of damming for hydro-electricity. By the mid-1980's very few Pedder Galaxias were found to be remaining in the area. The last recording of Pedder Galaxias in its natural habitat occurred during 1996 and comprehensive surveys undertaken since have not yielded any further records in its natural habitat.

Two translocated populations of the species exist, one at Lake Oberon, 12km southwest of Lake Pedder, and the other at Strathgordon Dam, within the same catchment as Lake Pedder. Both were established as part of the recovery plan for the species. Although there has been breeding success within the translocated population at Lake Oberon, there is currently no evidence of breeding within the population at Strathgordon Dam. Both translocated populations are located outside the previous known range of the species. There is also no evidence to suggest that this species is surviving in its natural habitat. Further, there does not appear to be any substantial areas of former habitat suitable for reintroduction of Pedder Galaxias. It is considered that the species is now extinct in what remains of its natural habitat.

The Pedder Galaxias is currently listed as endangered under the Tasmanian Threatened Species Protection Act 1995.

EPBC Act criteria.

The EPBC Act provides for the listing of native species in the category 'Extinct in the Wild'. Section 179 (2) states that:

'A native species is eligible to be included in the extinct in the wild category at a particular time if, at that time:

1. it is known only to survive in cultivation, in captivity, or as a naturalised population well outside its past range; or
2. it has not been recorded in its known and/or expected habitat, at appropriate seasons, anywhere in its past range, despite exhaustive surveys over a time frame appropriate to its life cycle and form.'

The Pedder Galaxias meets both criteria for listing in the extinct in the wild category. Justification is as follows:

Historic Distribution

Prior to the flooding of Lake Pedder in 1972, the Pedder Galaxias was naturally restricted to the original Lake Pedder and adjoining streams. After flooding, the distribution of the Pedder Galaxias initially increased throughout the new lake and into the adjacent Wedge River, Lake Gordon and McPartlans canal.

However, by the mid 1980s it became clear that the number of Pedder Galaxias had significantly declined.

Numbers continued to decline until surveys undertaken during the late 1980s by the Inland Fisheries Service (IFS) found that the Pedder Galaxias' distribution was restricted to only four tributary streams within the Lake Pedder impoundment. Further surveys undertaken by the IFS during the early 1990s found that the distribution had narrowed to only two tributary streams. Surveys undertaken between 1994 and 1997 resulted in the collection of only five specimens, the last of which occurred during 1996. Extensive surveys of the species' natural range were conducted by the IFS between 1998 and 2002, and the species was not located. It is considered that the survey effort for this species has been intensive. Given that the species has a generation length of approximately three to four years, and a lifespan of approximately six years, it is considered that the species is now extinct in what remains of its natural habitat.

Current Distribution

The Pedder Galaxias is now thought to only survive in two translocated populations, both of which were established as part of the recovery plan for the species. One population, established in 1992, occurs in Lake Oberon in the Western Arthur Range, approximately 12 km southwest of Lake Pedder. The other occurs in Strathgordon Dam in the same catchment as Lake Pedder, and was established in 1997. The population within Lake Oberon was surveyed in January 2001 and was found to be successfully breeding. It was estimated to consist of approximately 500 adults and a large number of pelagic juveniles. The second translocated population of 52 adults from Lake Oberon to Strathgordon dam has not as yet shown signs of successful breeding. In March 2002 a further 22 fish from Lake Oberon were added to Strathgordon dam and some further habitat improvements were undertaken. Additionally, attempts at captive breeding and artificial fertilisation have had limited success, with only 11 juveniles raised.

Although the translocated population at Lake Oberon is geographically relatively close to Lake Pedder (12km away), it is within an entirely separate catchment and there is no evidence to suggest the species ever occurred naturally in this catchment in the past. On this basis, the population that occurs at Lake Oberon is considered to exist well outside its past range. The Strathgordon Dam population is also geographically close to Lake Pedder, occurring within the same catchment, but is outside the natural distribution of the species. In addition it has shown no signs of being a viable, self-sustaining population.

Threats

The decline of the Pedder Galaxias following inundation of Lake Pedder was likely to be caused by a combination of predation and competition by exotic Brown Trout (Salmo trutta) and the native Climbing Galaxias (Galaxias brevipinnis), which were introduced into the Lake when it was flooded. Additionally, no areas of previously occupied habitat are suitable for reintroduction of the species, due to the large numbers of Brown Trout and Climbing Galaxias that are now well established in Lake Pedder. In-situ control of these species is not currently considered a feasible option for improving the habitat to allow for reintroduction of Pedder Galaxias. It is also considered that the introduced Redfin Perch (Perca fluviatilis) is a potential threat to the Pedder Galaxias, and as a mitigating measure, new operating procedures have been implemented to minimise the risk of Redfin Perch colonising Lake Pedder and placing additional pressure on any undetected Pedder Galaxias.

5. Conclusion

Information to date suggests that the Pedder Galaxias is likely to be extinct in its natural habitat. The translocated population at Strathgordon Dam has as yet shown no signs of breeding. The translocated Lake Oberon population, while successfully breeding, is not within the same catchment as Lake Pedder and there is no evidence to suggest the species ever occurred previously outside of Lake Pedder. The species therefore is known only to survive in a naturalised population well outside its past range.

Additionally, the Pedder Galaxias has not been located in Lake Pedder since 1996, despite a high level of survey effort. The Pedder Galaxias has no particular life-cycle phase which may have caused it to remain undetected throughout surveys, and given that the species lives for around 6 years, it is considered unlikely that the species still exists in the area. Therefore, the species has not been recorded in its known and/or expected habitat, at appropriate seasons, anywhere in its past range, despite exhaustive surveys over a time frame appropriate to its life cycle and form. The Pedder Galaxias meets EPBC Act criteria for listing as extinct in the wild.

6. Recommendation

TSSC recommends that the list referred to in section 178 of the EPBC Act be amended by transferring from the endangered category to the extinct in the wild category:

Galaxias pedderensis (Pedder Galaxias)

Publications used to assess the nomination

Crook, D., & Sanger, A. (1999). Recovery Plan for the Pedder, Swan, Clarence, Swamp and Saddled Galaxias. Inland Fisheries Commission, Tasmania.

Inland Fisheries Service. Field logbook survey data 1998-2002 (unpublished data)

Inland Fisheries Service. Freshwater Fish Facts: Pedder Galaxias. Retrieved from: www.ifs.tas.gov.au/fact_sheets/Pedder_galaxias.html

Jackson, J. (1999). Threatened fish profile: Pedder Galaxias. Australian Society for Fish Biology Inc. Newsletter. Retrieved from: www.asfb.org.au/research/spec/tfp_pgalaxias.htm

Jackson, J.E. (2004). Tasmanian Galaxiidae Recovery Plan 2004-2008. Inland Fisheries Service, Hobart.

Threatened Species Unit (1998). Threatened Species Listing Statement: Pedder Galaxias. Parks and Wildlife Service, Tasmania.

Conservation advice

The Pedder Galaxias is endemic to southwest Tasmania (Southern Tasmanian Natural Resource Management region) and was originally known only to occur in Lake Pedder. Lake Pedder and surrounding areas were inundated in 1972 as a result of damming for hydro-electricity. By the mid-1980's very few Pedder Galaxias were found to be remaining in the area. The last recording of Pedder Galaxias in its natural habitat occurred during 1996 and intensive survey effort since then have not yielded any further records of the species in its natural habitat. It is considered that the species is now extinct in what remains of its natural habitat.

Two translocated populations of the species exist, one at Lake Oberon, 12km southwest of Lake Pedder, and the other at Strathgordon Dam, within the Lake Pedder catchment. Both were established as part of the Recovery Plan for the species. Although there has been breeding success within the translocated population at Lake Oberon, there is currently no evidence of breeding within the population at Strathgordon Dam. Both translocated populations are located outside the previous known range of the species.

No areas of the species' previously known habitat is currently considered suitable for reintroduction of the species, due to large numbers of introduced Brown Trout and Climbing Galaxias, which are known to predate and compete with the Pedder Galaxias.

The priority recovery and threat abatement actions required for this species are:

• Continue to monitor presence of Pedder Galaxias in Lake Oberon and Strathgordon Dam
• Other actions as outlined in the Recovery Plan for this species

This list does not encompass all actions that may be of benefit to this species but highlights those that are considered to be of the highest priority at the time of listing.

Priority for the development of recovery plan: There is currently an Australian Government-adopted Recovery Plan in place for this species.