CASE STUDY SELECTED SPECIES – TASMANIA
Threatened Tasmanian Burrowing Crayfish – Tasmania
(d’Arville, Doran and Richardson 2008)
Description
Threatened Tasmanian burrowing crayfish are little known to the wider community, yet
they play a significant role in the regulation of freshwater systems. All of the species of
burrowing crayfish currently listed under State and Commonwealth threatened species
legislation in Tasmania are in the genus Engaeus.
There are 35 described species of Engaeus in Australia, 15 of these are found in Tasmania,
and 13 are endemic to the State. Freshwater burrowing crayfish, which are also found in
three other genera, are found across the State, from the boggy peatlands of Tasmania’s
south-west, to the banks of flowing streams in the north and to paddocks in the State’s
northern midlands.
The ecological, biological, geographical and evolutionary aspects of burrowing crayfish
species have been studied in Tasmania for more than a century (Richardson et al 2006).
The University of Tasmania and various museums hold extensive burrowing crayfish
collections. The assessment of hydro-electric development proposals and the collation of
World Heritage Area catalogues has meant that largely inaccessible areas such as the
State’s far south-west have been broadly surveyed (Richardson et al 2006). These surveys
have provided a comprehensive database from which to work, in combination with longterm survey sites that have been maintained since the 1980s. Consequently, there is a good
understanding of these species and the processes threatening them.
Significance
These threatened species include the most terrestrially-adapted of the world’s crayfish.
Some of them may play an important role in the ecosystem in which they are found,
aerating and draining soils and providing habitat for other species. Crayfish are important
indicators of water quality and depend on the same water management conditions that
benefit local urban communities (Doran 2000).
Many Engaeus species have restricted distributions. Some of the most terrestrial species
depend on surface run-off; this limits their dispersal ability, as they are not associated with
waterways. Combined with the naturally disjunct nature of aquatic habitats, this means
that the group displays a high degree of local speciation. The high level of endemicity
within the State makes them of national conservation significance.
Five Tasmanian Engaeus species are listed as threatened to varying degrees, under State
and Commonwealth legislation. The species are listed due to their restricted distributions
and exposure to threatening processes.
Common Name
Scientific Name
TSPA 1995*
EPBCA 1999**
Scottsdale burrowing crayfish
E. spinicaudatus
Endangered
Endangered
Furneaux burrowing crayfish
E. martigener
Vulnerable
Endangered
Central north burrowing crayfish
E. granulatus
Endangered
Endangered
Mt. Arthur burrowing crayfish
E. orramakunna
Vulnerable
Vulnerable
Burnie burrowing crayfish
E. yabbimunna
Vulnerable
Vulnerable
*Tasmanian Threatened Species Protection Act 1995
**Commonwealth Environment Protection and Biodiversity Conservation Act 1999
Data and information
In 1998-99, the Department of Primary Industries, Water and the Environment (now, the
Department of Primary Industries, Parks, Water and Environment (DPIPWE)), and what is
now the Forest Practices Authority (FPA) established long term monitoring sites for three
of these species (E. spinicaudatus, E. orramakunna and E. yabbimunna). These were
developed to investigate the local effect that disturbances such as forest clearing and fires
have on these species. The sites were surveyed in winter and summer until 2004. The data
is maintained at FPA. The monitoring sites were designed so that data collected during
subsequent visits can be linked back to the original surveys. The Burrowing Crayfish
Group Recovery Plan 2001-2005 (Doran 2000) is a valuable source of information about
these species.
Long term monitoring of other burrowing crayfish species, in the genera Ombrastacoides
and Spinastacoides, has been conducted by the University of Tasmania, for a number of
decades in the south- west of Tasmania. The information from such monitoring has been
presented in a number of publications (eg. Hansen & Richardson 2006, Richardson et al
2006, Hansen and Richardson 2000) and will be valuable for future assessments of the
conservation needs of these genera.
Management requirements and issues
The listed Engaeus species are exposed to a number of threatening processes, which
require a level of management that will protect and conserve the species. The main
threatening processes are those that affect water quality and quantity, soil structure and
composition, and food availability. Forestry and agricultural practices, stock movement
around creeks and swamps, wild fire, and urban development influence these factors most
significantly (Bryant & Jackson 1999, Doran 2000).
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It is recognised that the management of these species will have direct biodiversity
conservation benefits. Management will also have incidental beneficial consequences for
water quality and waterway health affecting nearby communities (Doran 2000).
Management actions and responses
On public land where these threatened Engaeus species are found, no major reservation
changes have been made. However private land conservation programs (such as the
Private Forest Reserves Program) have protected the habitat of various listed burrowing
crayfish species on several properties.
Ongoing distributional surveys have been conducted for all species, and there is increasing
knowledge of species ranges, but much of this work has been opportunistic rather than
strategic. Engaeus martigener habitat has been assessed prior to and following a major fire
event, which has contributed to understanding of this species’ response to fire and the
potential risk that fire poses to the species.
Engaeus granulatus has been at the centre of work conducted by various organisations.
The Central North Field Naturalists have undertaken habitat improvement for
E. granulatus in urban parks and wetlands, while the Tasmanian Land Conservancy has
established the Dorothy Reeves Reserve, recently renamed the Rubicon Sanctuary, at Port
Sorell protecting important E. granulatus habitat. In cooperation with the University of
Tasmania, the Forest Practices Authority has also undertaken targeted work in areas
containing this species.
The Launceston Environment Centre and DPIPWE have provided education about
burrowing crayfish and their management to agricultural communities; they have also
conducted fencing and management projects in such areas to protect E. yabbimunna and
E. spinicaudatus from threatening processes such as soil compaction by cattle or hazard
reduction burns. Management prescriptions for commercial forestry are well developed for
most species, and are currently under review. Following accidental loss of prime
E. orramakunna habitat in 2001, the Forest Practices Authority reinforced the need for
detailed planning and boundary marking of important habitat. Burrowing crayfish
protection has become a major part of ongoing Forest Practices training courses.
Private and State developers have not always recognised the importance of undertaking
adequate surveys for these species. However, general community involvement has been
satisfying, with much interest being shown towards the conservation of burrowing crayfish
once the community has been made aware of their presence and the processes threatening
them.
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Outcomes
Populations of E. yabbimunna and E. orramakunna are relatively secure when compared
to the other threatened Engaeus species. At this stage little is known about the Furneaux
species, E. martigener. Engaeus granulatus and E. spinicaudatus are both in very
precarious positions.
These species require urgent ongoing work in order to prevent their up-listing to the status
of Critically Endangered on the Environment Protection and Biodiversity Conservation
Act 1999 (EPBC Act).
Future scenario
Future revisions of the Burrowing Crayfish Group Recovery Plan will incorporate E.
granulatus; this is a relatively new addition to the Threatened Species Protection Act 1995
(TSPA) and the EPBC Act and so was not included in the original version. There are two
other described Engaeus species that are potentially threatened, and new Engaeus species
that have only recently been discovered and are yet to be described; all of these species
require status assessment. Newly described burrowing crayfish species in the genera
Ombrastacoides and Spinastacoides may qualify to be included in the TSPA and EPBC
Act. Assessments of these unlisted species are currently being planned, as is a review of
the current Recovery Plan.
In the future it will be necessary to increase Local Government awareness and
involvement in the protection of this group of species. In agricultural areas, cattle
management and farm dam construction need to be a focus for future education and
action. Communication between agricultural landowners and Government agencies is
vital, particularly for the protection of E. granulatus and E. spinicaudatus. Focussed
strategic surveys for Tasmanian burrowing crayfish must be planned and conducted in the
near future, especially before developments are approved or when changes in land use are
being planned. These actions are vital if we are to conserve the biodiversity of Tasmanian
and indeed Australian, burrowing crayfish and the various ecosystems in which they are
found.
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Figure 1. The distribution of Threatened Tasmanian burrowing crayfish species.
Engaeus yabbimunna, E. martigener, E. granulatus, E. orramukunna and
E. spinicaudatus.
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References
Doran NE (2000). Burrowing Crayfish Group Recovery Plan 2001-2005. Department of
Primary Industries, Water and Environment, Hobart.
Richardson A, Doran N & Hansen B (2006). The geographic ranges of Tasmanian
crayfish: extent and pattern, Freshwater Crayfish, vol. 15, pp.
Bryant SL & Jackson J (1999). Tasmania’s Threatened Fauna Handbook: what, where
and how to protect Tasmania’s threatened animals. Threatened Species Unit, Parks and
Wildlife Service, Hobart.
Hansen B & Richardson AMM (2000). Conservation implications of a review of the freshwater
crayfish genus Parastacoides (Decapoda: Parastacidae), Crustacean Issues, Vol. 12, pp. 799805.
Hansen, B & Richardson AMM (2006). A revision of the Tasmanian endemic freshwater
crayfish genus Parastacoides (Crustacea: Decapoda: Parastacidae), Invertebrate
Systematics Vol. 20, No.6, pp. 713-769.
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