Biodiversity

Species Profile and Threats Database


For information to assist proponents in referral, environmental assessments and compliance issues, refer to the Policy Statements and Guidelines (where available), the Conservation Advice (where available) or the Listing Advice (where available).
 
In addition, proponents and land managers should refer to the Recovery Plan (where available) or the Conservation Advice (where available) for recovery, mitigation and conservation information.

EPBC Act Listing Status Listed as Endangered
Listing and Conservation Advices Commonwealth Conservation Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009j) [Conservation Advice].
 
Commonwealth Listing Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009m) [Listing Advice].
 
Recovery Plan Decision Recovery Plan not required, "the approved conservation advice for the species now provides sufficient direction to implement priority actions and mitigate against key threats. Further actions are being implemented as described in the Western Australian Department of Environment and Conservation's 'Dunsborough Burrowing Crayfish (Engaewa reducta), Margaret River Burrowing Crayfish (Engaewa pseudoreducta) and Walpole Burrowing Crayfish (Engaewa walpolea) Recovery Plan 2007-2016. Interim Recovery Plan No. 41' (14/04/2009)".
 
Adopted/Made Recovery Plans
Federal Register of
    Legislative Instruments
Inclusion of species in the list of threatened species under section 178 of the Environment Protection and Biodiversity Conservation Act 1999 (79) (14/04/2009) (Commonwealth of Australia, 2009n) [Legislative Instrument].
 
State Government
    Documents and Websites
WA:Draft Dunsborough Burrowing Crayfish (Engaewa reducta), Margaret River Burrowing Crayfish (Engaewa pseudoreducta) and Walpole Burrowing Crayfish (Engaew walpolea) Recovery Plan 2007-2016 (Western Australian Department of Environment and Conservation (WA DEC), 2008a) [State Recovery Plan].
State Listing Status
WA: Listed as Vulnerable (Wildlife Conservation Act 1950 (Western Australia): September 2013 list)
Non-statutory Listing Status
IUCN: Listed as Endangered (Global Status: IUCN Red List of Threatened Species: 2013.1 list)
Scientific name Engaewa walpolea [82676]
Family Parastacidae:Decapoda:Malacostraca:Arthropoda:Animalia
Species author Horwitz & Adams, 2000
Infraspecies author  
Reference Horwitz, P. & Adams, M. 2000 Invertebrate Taxonomy 14: 655-680 [673 figs 10A-J]
Distribution map Species Distribution Map

This is an indicative distribution map of the present distribution of the species based on best available knowledge. See map caveat for more information.

Illustrations Google Images

The current conservation status of the Walpole Burrowing Crayfish, Engaewa walpolea, under Australian and State Government legislation, is as follows:

National: Listed as Vulnerable under the Environment Protection and Biodiversity Conservation Act (1999).

Western Australia: Listed as Vulnerable under the Wildlife Conservation Act 1950.

Scientific name: Engaewa walpolea

Common Name: Walpole Burrowing Crayfish

The taxonomic status of the Walpole Burrowing Crayfish is conventionally accepted (Horwitz & Adams 2000).

The Walpole Burrowing Crayfish is a small burrowing crayfish up to 50 mm in length. It generally has a pale to mid-brown colour with purplish-blue claws. The narrow abdomen is often shorter than the head and thorax. Other distinguishing features are the reduced eye size, large claws adapted to digging, and the fingers of the claws move in a vertical plane.

The Walpole Burrowing Crayfish is only distinguished from the closely related Margaret River Burrowing Crayfish, (E. pseudoreducta) and Dunsborough Burrowing Crayfish, (E. reducta) by examining anatomical features under a microscope. Walpole Burrowing Crayfish exhibits distinct anatomical features including a backward pointing tip on the keel of the sternum (a central ridge running between the leg attachment points on the underside of the thorax), and granulate carinae (bead-like ridges) on the underside of the propodus (penultimate leg segment). However, these species are more easily distinguished from each other by the river system in which they are found, as they have extremely limited capacity for dispersal and are geographically isolated (Horwitz & Adams 2000).

The Walpole Burrowing Crayfish is endemic to southern Western Australia. The species is known only from three locations near Walpole, approximately 450 km south of Perth. (TSSC 2009j). The species has been collected from 25 sites within these three locations, 24 of which are within Walpole-Nornalup National Park (TSSC 2009m) in the South Coast Natural Resource Management Region.

The extent of occurrence of the Walpole Burrowing Crayfish has been estimated at approximately 55 km² based on the area encompassed by all known sites (TSSC 2009m).

The species' area of occupancy is estimated at 10 km² and has been calculated by measuring the area of vegetated swamp/drainage system habitats where the species has been collected (TSSC 2009m). The discovery site of the Walpole Burrowing Crayfish, in 1981, was in a recently logged section of private property on Valley of the Giants Road near Bow Bridge, but all subsequent discoveries have been located within the Walpole-Nornalup National Park (WA DEC 2008a). The species has not been found again at the original discovery site despite repeated searching (WA DEC 2008a).

The distribution of the three known populations is isolated and subject to a number of threats including land clearing for agriculture and forestry, cattle grazing and farm dam construction (Burnham 2005; Burnham et al. 2007).

Several surveys of the type of site where the Walpole Burrowing Crayfish was first recorded, have been conducted. The species was first found, in 1992–93, in the Walpole-Nornalup National Park close to the township of Walpole. Surveys in 2006 found additional populations in the Walpole-Nornalup National Park.

There are no population estimates for the Walpole Burrowing Crayfish, though numbers are likely to be low based on the highly restricted area of occupancy.

The generation length of the Walpole Burrowing Crayfish is unknown, however they are considered to be long-lived with slow maturation (WA DEC 2008a).

Twenty-four out of the twenty-five sites, where the species is known to occur, are located within Walpole-Nornalup National Park (TSSC 2009m).

The Walpole Burrowing Crayfish uses a variety of habitats that provide very moist soils and a shallow, very accessible watertable. These habitats include surface seepages, swamp plains and shallow swampy creeklines. Soil types range from coarse gravelly sand, sandy loams and silty loams rich in organic material. The Walpole Burrowing Crayfish constructs burrows in these soils that extend down to the watertable. The burrows of Walpole Burrowing Crayfish are generally short and inconspicuous, and the soil pellet chimneys that are often characteristic of other Engaewa species' burrows, are reduced or absent.

Native vegetation types associated with these habitats are Karri (Eucalyptus diversicolor) woodlands, sedges, peatbogs and heathlands. One population is known from an area with non-native vegetation cover comprising introduced Tree Ferns (Dicksonia species), with Kikuyu Grass (Pennisetum clandestinum) and Cape Gooseberry (Physalis peruviana) understorey (Burnham 2005; Burnham et al. 2007).

There is little data on the life cycle, or fecundity, of the Walpole Burrowing Crayfish. However one female has been collected carrying 15 juveniles, and two females have been collected carrying 8 and 15 eggs respectively. These egg counts are similar to the closely related Engaewa similis, in which egg counts of up to 25 have been recorded (Horwitz & Adams 2000).

The Walpole Burrowing Crayfish is difficult to study in the wild and details of diet and reproduction are not known. Other burrowing freshwater crayfish are believed to eat rotting wood, detritus, root material and occasionally animal material (Bryant & Jackson 1999b; Growns & Richardson 1988; Suter & Richardson 1977).

The movement and dispersal abilities of Engaewa spp. are poorly understood. Collections of Walpole Burrowing Crayfish in spring 2006 were a significant event with the first ever observations of this species walking around in the bottom of shallow puddles. The time of the year, weather conditions and habitat may have been influencing factors contributing to this event of surface movement (Burnham 2005).

Walpole Burrowing Crayfish are difficult to detect in the wild because the species' burrows are generally short and inconspicuous and the soil pellet chimneys, that are often characteristic of other Engaewa species' burrows, are reduced or absent (TSSC 2009j). Microscopic examination is usually required to detect the distinct backward pointing tip on the keel of the sternum and the granulate carinae (bead-like ridges) on the underside of the penultimate leg segment.

The main threat to the Walpole Burrowing Crayfish has been habitat loss and destruction caused by anthropogenic disturbance within the species' range. Land clearing for agriculture and forestry has removed habitat for the species. Farm dam construction has flooded suitable habitat and has altered surface water and groundwater flows. Cattle grazing has physically destroyed burrows through trampling and soil compaction, has created serious erosion and has impaired soil permeability and water holding capacity (Burnham 2005; Burnham et al. 2007). These processes have led to the extinction of one population and have likely led to other unrecorded, localised population extinctions (WA DEC 2008a).

Potential threats to Walpole Burrowing Crayfish populations within Walpole-Nornalup National Park include reduced rainfall from climate change, feral pigs (Sus scrofa) and inappropriate fire regimes.

The annual rainfall, in the lower Walpole-Nornalup catchment, has gradually decreased since 1951 (Hodgkin & Clarke 1988). Reduced rainfall from climate change may lead to the drying out and loss of swamp and drainage system habitats (WA DEC 2008a).

Feral pigs may damage habitat through ground-rooting feeding behaviour and directly prey on crayfish during rare surfacing events. Feral pig numbers are increasing in south-western Western Australia due to illegal introductions by recreational pig hunters and the subsequent reproductive success of the feral pigs (Spencer &Hampton 2005)

The impact of fire on the Walpole Burrowing Crayfish has not been investigated, but fire can severely damage swamp habitats (WA DEC 2008a). It is suggested that, whilst not directly threatening individual Walpole Burrowing Crayfish, burning may destroy the organic content, structure and water holding capabilities of soils found in those habitats, making it more prone to future fires and thus less suitable for the species through acidification and metal toxification. Fire fighting techniques could also be detrimental to a species with such a restricted distribution (WA DEC 2008a).

A further threat that has not been quantified but may be detrimental to the Walpole Burrowing Crayfish is disease from introduced crayfish species (Burnham 2005; Burnham et al. 2007).

Minister's reasons for recovery plan decision

The approved conservation advice for the species now provides sufficient direction to implement priority actions and mitigate against key threats. Further actions are being implemented as described in the Western Australian Department of Environment and Conservation's 'Dunsborough Burrowing Crayfish (Engaewa reducta), Margaret River Burrowing Crayfish (Engawea pseudoreducta) and Walpole Burrowing Crayfish (Engaewa walpolea) Recovery Plan 2007-2016. Interim Recovery Plan No. 41'.

A nationally adopted recovery plan is not considered to be necessary at this time.

Other recovery actions

The draft Dunsborough Burrowing Crayfish (Engaewa reducta), Margaret River Burrowing Crayfish (Engaewa pseudoreducta) and Walpole Burrowing Crayfish (Engaew walpolea) Recovery Plan 2007-2010 (WA DEC 2008a) outlines the following recovery objectives for these species:

  • Determine the current distribution and identify additional populations of Engaewa.
  • Increase public awareness and participation in threatened species protection.
  • Protect habitat.
  • Improve knowledge of Engaewa life history and ecology.

The Conservation Advice for the Walpole Burrowing Crayfish (TSSC 2009j) outlines research priorities and priority actions for the protection of the species:

  • Research into the species life history (longevity, dispersal, reproduction).
  • Research into the species ability to withstand desiccation, acidity and low dissolved oxygen levels and effects of fire.
  • Design and implement a monitoring program, including improved ways of catching and releasing animals for study (currently animals must be dug out by hand).
  • Undertake survey work in suitable habitat and potential habitat to locate any additional populations/occurrences.
  • Monitor known populations to identify key threats.
  • Monitor the progress of recovery, including the effectiveness of management actions and the need to adapt them if necessary.
  • Manage known sites to prevent introduction of invasive weeds, which could become a threat to the Walpole Burrowing Crayfish, using appropriate methods.
  • Manage feral pigs at known sites to minimise impacts from ground-rooting and wallowing.
  • Implement an appropriate fire regime for the habitat of local populations.

The following documents may inform the conservation of this species:

  • The Dunsborough Burrowing Crayfish (Engaewa reducta), Margaret River Burrowing Crayfish (Engaewa pseudoreducta) and Walpole Burrowing Crayfish (Engaew walpolea) Recovery Plan 2007-2010 (WA DEC 2008a) has been prepared to guide threat abatement and management strategies.
  • The Conservation Advice for the Walpole Burrowing Crayfish (TSSC 2009j)

The following table lists known and perceived threats to this species. Threats are based on the International Union for Conservation of Nature and Natural Resources (IUCN) threat classification version 1.1.

Threat Class Threatening Species References
Agriculture and Aquaculture:Agriculture and Aquaculture:Land clearing, habitat fragmentation and/or habitat degradation Commonwealth Conservation Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009j) [Conservation Advice].
Commonwealth Listing Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009m) [Listing Advice].
Agriculture and Aquaculture:Livestock Farming and Grazing:Grazing pressures and associated habitat changes Commonwealth Conservation Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009j) [Conservation Advice].
Biological Resource Use:Hunting and Collecting Terrestrial Animals:Harvesting for recreational purposes Commonwealth Listing Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009m) [Listing Advice].
Biological Resource Use:Logging and Wood Harvesting:Habitat loss, modification and degradation due to timber harvesting Commonwealth Conservation Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009j) [Conservation Advice].
Commonwealth Listing Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009m) [Listing Advice].
Climate Change and Severe Weather:Climate Change and Severe Weather:Climate change altering atmosphere/hydrosphere temperatures, rainfall patterns and/or frequency of severe weather events Commonwealth Conservation Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009j) [Conservation Advice].
Commonwealth Listing Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009m) [Listing Advice].
Climate Change and Severe Weather:Habitat Shifting and Alteration:Habitat loss, modification and/or degradation Commonwealth Listing Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009m) [Listing Advice].
Invasive and Other Problematic Species and Genes:Invasive Non-Native/Alien Species:Grazing, tramping, competition and/or habitat degradation Sus scrofa (Pig) Commonwealth Conservation Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009j) [Conservation Advice].
Commonwealth Listing Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009m) [Listing Advice].
Invasive and Other Problematic Species and Genes:Invasive and Other Problematic Species and Genes:Presence of pathogens and resulting disease Commonwealth Listing Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009m) [Listing Advice].
Natural System Modifications:Dams and Water Management/Use:Alteration of hydrological regimes and water quality Commonwealth Listing Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009m) [Listing Advice].
Natural System Modifications:Dams and Water Management/Use:Changes to hydrology including construction of dams/barriers Commonwealth Conservation Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009j) [Conservation Advice].
Commonwealth Listing Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009m) [Listing Advice].
Natural System Modifications:Fire and Fire Suppression:Inappropriate and/or changed fire regimes (frequency, timing, intensity) Commonwealth Conservation Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009j) [Conservation Advice].
Commonwealth Listing Advice on Engaewa walpolea (Threatened Species Scientific Committee (TSSC), 2009m) [Listing Advice].

Bryant, S. & J. Jackson (1999b). Tasmania's Threatened Fauna Handbook: What, Where and How to Protect Tasmania's Threatened Animals. Hobart, Tasmania: Threatened Species Unit, Parks and Wildlife Service.

Burnham, Q.F. (2005). The systematics of the reducta complex of the burrowing freshwater crayfish Engaewa Riek. Hons. Thesis. Perth: Edith Cowan University.

Burnham, Q.F., A. Koenders & P. Horwitz (2007). Field studies into the biology and conservation requirements of Engaewa species in the South-West and Warren DEC Regions. Final Report Prepared for Department of Environment and Conservation 30 November 2007.

Growns, I.O. & A.M.M. Richardson (1988). The diet and burrowing habits of the freshwater crayfish Parastacoides tasmanicus tasmanicus Clark (Decapoda: Parastacidae). Australian Journal of Marine and Freshwater Research. 39:525-534.

Horwitz, P. & M. Adams (2000). The systematics, biogeography and conservation status of the species in the freshwater crayfish genus Engaewa Riek (Decapoda: Parastacidae) from south-western Australia. Invertebrate Taxonomy. 14:655-680.

Spencer, P.B.S. & J.O. Hampton (2005). Illegal translocation and genetic structure of feral pigs in Western Australia. Journal of Wildlife Management. 69:377-384.

Suter, P.J. & A.M.M. Richardson (1977). The biology of two species of Engaeus (Decapoda: Parastacidae) Tasmania. III. Habitat, food, associated fauna and distribution. Australian Journal of Marine and Freshwater Research. 28:95-103.

Threatened Species Scientific Committee (TSSC) (2009j). Commonwealth Conservation Advice on Engaewa walpolea. [Online]. Department of the Environment, Water, Heritage and the Arts. Available from: http://www.environment.gov.au/biodiversity/threatened/species/pubs/82676-conservation-advice.pdf.

Threatened Species Scientific Committee (TSSC) (2009m). Commonwealth Listing Advice on Engaewa walpolea. [Online]. Department of the Environment, Water, Heritage and the Arts. Available from: http://www.environment.gov.au/biodiversity/threatened/species/pubs/82676-listing-advice.pdf.

Western Australian Department of Environment and Conservation (WA DEC) (2008a). Draft Dunsborough Burrowing Crayfish (Engaewa reducta), Margaret River Burrowing Crayfish (Engaewa pseudoreducta) and Walpole Burrowing Crayfish (Engaew walpolea) Recovery Plan 2007-2016. [Online]. Western Australia: Department of Environment and Conservation. Available from: http://www.dec.wa.gov.au/pdf/plants_animals/threatened_species/frps/41-burrowing-crayfish-recovery-plan-01feb2009.pdf.

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This database is designed to provide statutory, biological and ecological information on species and ecological communities, migratory species, marine species, and species and species products subject to international trade and commercial use protected under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act). It has been compiled from a range of sources including listing advice, recovery plans, published literature and individual experts. While reasonable efforts have been made to ensure the accuracy of the information, no guarantee is given, nor responsibility taken, by the Commonwealth for its accuracy, currency or completeness. The Commonwealth does not accept any responsibility for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the information contained in this database. The information contained in this database does not necessarily represent the views of the Commonwealth. This database is not intended to be a complete source of information on the matters it deals with. Individuals and organisations should consider all the available information, including that available from other sources, in deciding whether there is a need to make a referral or apply for a permit or exemption under the EPBC Act.

Citation: Department of the Environment (2014). Engaewa walpolea in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Fri, 1 Aug 2014 09:58:22 +1000.