|Scientific Name:||Euastacus yarreansis|
|Species Authority:||(McCoy, 1888)|
|Red List Category & Criteria:||Vulnerable 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 yarreansis has been assessed as Vulnerable B1ab(iii). This species has a severely fragmented distribution, and an extent of occurrence of approximately 9,000 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. This species is also subject to illegal fishing pressure which can result in stunted growth. It also faces the consequences of global temperature rise. As a restricted range species, dependent on cool, clear 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.
|Range Description:||This species is endemic to Australia. The species inhabits a roughly semicircular area around the State of Victoria's capital city, Melbourne. It is found in all the larger southern flowing streams of Victoria between the Gellibrand River and the Bunyip/Tarrago River systems at elevations below 300m above sea level (Riek 1969, Morgan 1986). The distribution of the species appears to be severely fragmented, primarily into eastern (east of Melbourne) and western (south-west of Geelong) components, with some outlying records to the north-west (O'Brien 2007). Morgan (1986) discussed some variation in morphology and size at maturity between populations. The estimated extent of occurrence is 9,000 km², although this area has been very heavily developed (i.e. includes Melbourne and other cities) and the area of occupancy of this is likely to be much less than the extent of occurrence (J. Coughran and J.M. Furse pers. comm. 2009).|
|Range Map:||Click here to open the map viewer and explore range.|
There is no population information available for this species (J. Coughran and J.M. Furse pers.comm. 2009).
|Habitat and Ecology:||
This species inhabits creeks, streams and rivers. The vegetation in the species range includes dry sclerophyll forest and acacia, blackberry in semi-cleared areas and tree ferns in some sheltered valleys. This species is present in some cleared areas, especially if vegetation persists along streams (Morgan 1986). The species is sometimes sympatric with Euastacus kershawi (J. Coughran and J.M. Furse pers.comm. 2009).
The main threats to this species are the effects of climate change, over exploitation and the introduction of species, including exotic species (J. Coughran and J.M. Furse pers. comm. 2009). Climate change threatens this species, particularly with regard to altered hydrological regimes and severe weather events. Climate change modelling predicts that southereastern mainland Australia will experience a warmer and drier climate, leading to decreased run-off and soil moisture (Chiew and McMahon 2002, Howden 2003). This alteration of hydrological regimes is likely to impact environmental flows, particularly in areas of increasing demand for domestic, industrial and agricultural water supplies (Hennessy 2006).
Although technically protected by recreational fishing regulations, this restricted range species is susceptible to over exploitation through fishing pressure (O'Brien 2007). Recreational fishing (in particular the taking of large adults) has the capacity to lead to serious and far reaching impacts on population structure (i.e. the stunted population phenomenon (Huner and Lindqvist 1985, Tulonen et al. 2008), including impairment of reproductive success in females (Tulonen et al. 2008).
Exotic or introduced species can cause potentially large scale threats from exotic fishes such as Brown Trout of Redfin Perch, which are prevalent throughout the region (Davies and McDowall 1996, Rowe et al. 2008). Exotic introduced species such as cats, foxes, pigs and 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 therefore could have localized impacts on this species (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, goats, trout, perch, 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
There are no species-specific conservation measures in place for this species. Its distribution range may coincide with a number of national parks, however its distribution also coincides with a heavily populated and developed area (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, and resilience to effects of exotic species (J. Coughran and J.M. Furse pers. comm. 2009). In Victoria, a minimum recreational fishing size of 90 mm occipital carapace length (OCL) applies to spiny crayfish (DPI 2007). This species does not attain that size, so is indirectly protected by this restriction (J. Coughran and J.M. Furse pers. comm. 2009).
|Citation:||Coughran, J. & Furse, J. 2010. Euastacus yarreansis. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 11 December 2013.|
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