|Scientific Name:||Euastacus bispinosus|
|Species Authority:||Clark, 1936|
|Red List Category & Criteria:||Vulnerable B1b(iii,v)c(iv) ver 3.1|
|Assessor/s:||Furse, J. & Coughran, 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 bispinosus has been assessed as Vulnerable under criteria B1b(iii,v)c(iv). This species has an estimated extent of occurrence of 12,700 km2 and is undergoing a continuing decline in quality of habitat as a result of land use change in the catchment. This species has also been subject to extensive harvesting; in combination with this species slow reproductive rate, this has resulted in a significant decline in the number of mature individuals. This species is also said to exhibit extreme fluctuations in the number of mature individuals. Monitoring of the population is needed to better understand at what rate it is being lost across its range.
This species is endemic to Australia. It is recorded from the Glenelg River system and its tributaries, in western Victoria, and in Ewens Ponds south of Mount Gambier, South Australia. It is found from close to sea level to altitudes of 320 m and probably higher (Riek 1969; Morgan 1986). There has been an apparent disappearance from Rocklands Reservoir (J.M. Furse and J. Coughran pers. comm. 2008). The extent of occurrence is estimated at approximately 10,000 km2.
Native:Australia (South Australia, Victoria)
|Range Map:||Click here to open the map viewer and explore range.|
Population data for this species was documented by Barker (1992), and various aspects of growth, reproduction and general biology have also been studied (Honan and Mitchell 1995a,b,c; Honan 1998), making this one of the better understood species in the genus. It is a slow-growing and late-maturing species, and its population attributes appear unsuited to exploitation (Honan and Mitchell 1995a,c). This species is thought to exhibit extreme fluctuations in the number of mature individuals (J.M. Furse and J. Coughran pers. comm. 2009). This species is the least abundant of the three spiny crayfish species (Department of Sustainability and Environment 2007).
|Habitat and Ecology:||
This species is found in streams, rivers and ponds. The vegetation at lower altitude sites includes Eucalyptus and Leptospermum species, bracken, with wet sclerophyll forest and pine plantations in areas (Morgan 1986). This species prefers streams with shaded, well vegetated banks, and an abundance of woody debris (Morgan 1983).
This is a slow-growing species taking up to 12 years to reach sexual maturity (Van Praagh 2003). It reproduces annually, has a low dispersal rate, and is typically found at low densities (Honan and Mitchell 1990 a,b,c).
Climate change, particularly with regard to altered hydrological regimes and severe weather events (IPCC 2007, Westoby and Burgman 2006) is a potential threat to this species. Climate change modelling predicts that southeastern mainland Australia will experience a warmer and drier climate, leading to decreased run-off and soil moisture (Chiew and McMahon 2002, Howden 2002). This alteration of hydrological regimes is likely to impact environmental flows, particularly in areas of increasing demand for agricultural water supplies (Hennessy 2006).
The Glenelg River catchment has been extensively cleared, and modified, and river regulation, de-snagging, channelization and increased sedimentation have impacted in-stream habitat (Van Praagh 2003, O'Brien 2007). Construction of the Rocklands Reservoir is thought to have caused the local extinction of this species, which was recorded at the site prior to the dam's construction (Horwitz 1990).
The abundance of this species has been reduced through inappropriate levels of exploitation (Jones and Morgan 1994). Morgan (1983) observed evidence of heavy fishing activity in the Glenelg River system, and noted that populations of Euastacus could be heavily impacted in a single weekend of heavy fishing pressure. Barker (1992) found considerable variation in catch rates and sizes of this species across different sites. 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 fishes such as Brown Trout or Redfin Perch, which are prevalent throughout the region, potentially are a large scale threats for this species (Horwitz 1990, Davies and McDowall 1996, Rowe et al. 2008). Other exotic species (cats, foxes, goats) that have generally been found to impact on crayfish (e.g. 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,b,c) and could have localised impacts on this species, leading to declines in distribution and/or local abundance.
The range of the species coincides with several national parks. This species is listed as threatened under the Victorian Flora and Fauna Guarantee Act 1988, and an Action Statement under the Flora and Fauna Guarantee Act (1988) has been prepared (Van Praagh 2003). In South Australia there is no minimum legal length (i.e. size) for this species, but a bag limit of five individuals applies (PIRSA undated). The spiny crayfish fishery was closed in Victoria from 1983 until 1991 (Barker 1992). The current fishery for spiny crayfish is managed through a minimum size limit of 90 mm OCL, closed seasons and areas, and a bag limit of five per person per day (only one of which can exceed 120 mm OCL) (DPI 2007). Only three of the 11 Victorian species (Euasta armatus, E. bispinosus and E. kershawi) attain 90 mm OCL, so the regulations may increase pressure on these species.
Further research should be initiated to include population assessment and monitoring, investigations into thermal tolerance and resilience to exotic species (J.M. Furse and J. Coughran pers. comm. 2008)
|Citation:||Furse, J. & Coughran, J. 2010. Euastacus bispinosus. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 09 March 2014.|
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