|Scientific Name:||Euastacus yigara|
|Species Authority:||Short & Davey, 1993|
|Red List Category & Criteria:||Critically Endangered B1ab(iii) ver 3.1|
|Assessor(s):||Coughran, J. & Furse, J.|
|Reviewer(s):||Collen, B. & Richman, N.|
|Contributor(s):||Livingston, F., Livingston, F., Soulsby, A.-M., Batchelor, A., Dyer, E., Whitton, F., Milligan, H.T., Smith, J., Lutz, M.L., De Silva, R., McGuinness, S., Kasthala, G., Jopling, B., Sullivan, K. & Cryer, G.|
Euastacus yigara has been assessed as Critically Endangered under criterion B1ab(iii). This species is only known from a single location and has an extent of occurrence of around 10 km2. There has been a continuing decline in the quality of habitat due to the destructive nature of a number of exotic species in the area, some of which also predate upon this species. There is also destruction of suitable rainforest habitat in parts of its range. This species also faces the consequences of global temperature rise. As a restricted range species, dependent on cool, clear headwater streams, a slight increase in temperature could rapidly extirpate this species. Research should be initiated to include population assessment and monitoring, biological and life history information, habitat requirements, and resilience to effects of exotic species.
This species is endemic to Australia. It is currently known from a single site in O'Leary Creek, a tributary of the upper Tully River above Koombooloomba Dam, North Queensland (Short and Davie 1993). This species has an extent of occurrence of around 10 km2.
|Range Map:||Click here to open the map viewer and explore range.|
This species is apparently rare (J. Coughran and J. M. Furse pers. comm. 2009). Recent (Oct 2008) targeted surveys in a number of streams and gullies proximal to the type locality failed to locate any specimens of this species, although the habitat was apparently suitable (Coughran 2008a unpublished data, J. Coughran and J. M. Furse pers. comm. 2009).
|Habitat and Ecology:||This species is known to occur in river and creeks, and has been found under rocks in shallow water. They prefer rock/sand substratum, fringing simple notophyll vine forest with high water clarity (Short and Davie 1993).|
Given the apparently restricted range of each population, the species is susceptible to localized impacts, including bush fires, forest management, practices, habitat destruction and over exploitation by collectors. Climate change, including increasing temperature, alterations to hydrological regimes, severe weather events, loss of suitable rainforest habitat and increased potential for bushfires (Chiew and McMahon 2002, Howden 2003, Hughes 2003, Pittock 2003, Hennessy 2006, Westoby and Burgman 2006, IPCC 2007). There is a potential large scale threat from Cane Toads (Rhinella marina) (DEH 2004a) although there are no specific data on impacts for this species. Other exotic species (cats, foxes pigs, goats) that have generally been found to impact on crayfish (Green and Osbourne 1981, Horwitz 1990, Merrick 1995, Eyre et al. 1997, ACT Government 2007, O'Brien 2007) also occur in this species' range (DEH 2004a,c,d,e) and given the restricted distribution, could have impacts on this species by contributing to declines in its distribution and/or abundance (J. Coughran and J.M Furse pers. comm. 2009). Due to the narrow thermal tolerance of this species, and its restricted range (restricted to cool, headwater streams in forested catchments), global temperature increase has resulted in range contraction. This species is further compromised by the presence of exotic species (feral pigs, foxes, Cane Toads and cats) which are known to predate on crayfish and degrade riparian habitat; while the precise effects of these threats on this species are not yet well understood, they are believed to be significantly impacting the long term viability of the population (J. Furse and J. Coughran pers. comm. 2010).
There are no species specific conservation measures in place for this species, however its distribution range may coincide with the Koombooloomba Forest Reserve (J.Coughran and J.M. Furse pers. comm. 2009). Research should be initiated to include population assessment and monitoring, biological and life history information, habitat requirements, investigations into thermal tolerance, resilience to exotic species (J.Coughran and J.M. Furse pers. comm. 2009).
All species of the genus Euastacus in Queensland are officially no take species under the Fisheries Act 1994 and must be released if captured (DPIF 2007). There is no information available on the levels of compliance, although evidence of illegal poaching is frequently observed. It is also noted that species such as this species are not spiny (Morgan 1988; Short and Davie 1993; Coughran 2008b), and thus may be easily confused with smooth Cherax (unprotected) and inadvertently taken by recreational fishers (J. Coughran and J.M. Furse pers. comm. 2009).
|Citation:||Coughran, J. & Furse, J. 2010. Euastacus yigara. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 02 September 2015.|
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