Welcome to the fourth newsletter about the Giant Freshwater Crayfish Recovery Project being undertaken by Cradle Coast NRM
The Giant Freshwater Crayfish (Astacopsis gouldi) is the largest freshwater crustacean in the world and is unique to northern Tasmania It has been found in most of the northern rivers that flow into Bass Strait, except for the Tamar River, and in the Arthur-Pieman catchment on the west coast Astacopsis is a genus of crayfish endemic to Tasmania There are three species of Astacopsis: Astacopsis gouldi, Astacopsis franklinii and Astacopsis tricornis A franklinii is found in the eastern half of the state and A tricornis in the western part of the state
In contrast, the species of Engaeus, Geocharax, Ombrastacoides and Spinastacoides are small freshwater crayfish with a body length of under 10 cm. Within the genus Engaeus there are approximately 15 known species, 13 of which only occur in Tasmania. Most species of Engaeus are characterised by their ability to burrow. The burrowing crayfish live their entire life within their burrow systems in muddy banks, seepages and peaty areas. Burrows can be simple and shallow or complex and extensive. The distinctive chimneys at the entrances to the burrows are all that most of us will ever see of a burrowing crayfish.
The Giant Freshwater Crayfish can grow up to 6 kg and up to a metre in length. Its colour can vary from dark brown-green to black or blue. The Giant Freshwater Crayfish can be distinguished from any other Tasmanian crayfish by the ridge running down the middle of the rostrum (the pointed structure between the eyes). Sometimes they may have different sized claws if they are regenerating after having been in a fight. They are very slow-growing and long-lived, with females taking up to fourteen years before they can breed and males up to nine years They can live up to sixty years
Chimney of a burrowing crayfish.
Young crayfish prefer shallow, fast-flowing streams with bed materials such as cobbles and boulders that they use for shelter.
Adults often move to slower-flowing reaches where they like undercut banks to burrow in, or logs and boulders to seek shelter under.
They prefer well-vegetated streams with clear water and even cooler temperatures. In addition to providing shelter, in-stream logs and dead wood are critical for providing food. Vegetation along both banks of the waterway moderates temperature extremes and filters sediments from soil and effluent which would otherwise muddy the water and degrade crayfish habitat
There are three major threats to the survival of the Giant Freshwater Crayfish, these being loss of habitat and poaching
Land clearing, particularly the removal of woody vegetation from along and within waterways is a major issue Not only does it remove the shading effect and food source for the crayfish but can also lead to siltation and turbidity of the water
Sedimentation in streams is particularly a problem for the small animals when they are young as they find it difficult to find hiding places away from predators Stock access to waterways can also affect water quality and increase sedimentation
The Giant Freshwater Crayfish Recovery Project focussed on providing solutions: Good off stream watering points on a solid gravel base provide good quality water for stock; reduce sedimentation into waterways; and the gravel base reduces erosion from stock trampling around the trough
Poaching of crayfish, particularly the larger breeding adults can lead to the loss of populations and the decline in the species given how slow growing the species is Poaching has been illegal since 1998 and can attract fines of up to $105,000 under the threatened species legislation. Anyone with information relating to the illegal taking of protected species can email the Inland Fisheries Service at infish@ifs.tas.gov.au or call 1300 INFISH.
Other threats to the crayfish include alterations to stream flow such as culverts and farm dams, chemical or fertiliser runoff, climate change and over extraction of water.
A juvenile crayfish requires different stream characteristics than older animals
The Giant Freshwater Crayfish Recovery Project commenced in October 2019 and finishes in June 2023 It has worked with agricultural landholders in targeted sections of rivers in the Cradle Coast area The aim of the project is to protect known populations of Giant Freshwater Crayfish and improve the extent and quality of their habitat
Initially, the project team undertook a desktop analysis to identify potential stream reaches to target for project activities This took into consideration ecosystem values, land use, previous sightings and tagging of crayfish, woody vegetation quality, channel gradient and elevation We identified 40 priority areas to start with On-ground field checking was then undertaken, with sites that were too degraded or had limited habitat improvement potential being discarded. To be considered for the project, potential habitat improvement areas had to be at least one kilometre and have a link to existing good remnant native vegetation This reduced the priority areas to 14 Initial engagement activities were undertaken across these identified areas to gauge the level of landholder interest in participating in the project
The following areas were the final six priority or target areas where landholder projects were developed:
Part of the Flowerdale River and an unnamed tributary in the Lapoinya area
Black River near Newhaven Rd
Hook Creek and Detention River
Roger River, Spinks Creek, Upper Duck River
Lower Inglis River
The project worked with rural or agricultural landholders to implement habitat protection or improvement and provided technical advice to landholders, financial incentives to implement works, as well as demonstration and promotion events. 94 initial site visits were undertaken with landholders across the six priority catchments to identify and develop potential projects at each site.
Adequate widths or “buffers” between the top of the high bank and the riparian fence are essential to ensure vegetation can become established and hold the bank together in flood events, as well as providing a filter strip for sediment and nutrients flowing from the adjoining paddocks to the waterway
The types of works that were implemented by landholders included:
Riparian fencing to exclude stock and install off stream water points
Native vegetation establishment and weed control to improve shading and vegetation, and eventually provide timber recruitment into the waterway
Erosion control works to stabilise banks or beds of waterways
Establishment and management of filter zones or buffer strips through fencing and re-vegetation
Buffer widths are calculated from the top of the high bank from the river’s edge They need to be wide enough to allow deep rooting vegetation to establish or regenerate whose root systems will hold the bank together and reduce erosion. Provided gates are installed it also allows access for maintenance or stock recovery
Site monitoring
Establish conservation covenants and manage and link areas of good remnant native vegetation for conservation.
In total, 26 landholders initially entered into funding agreements to protect approximately 45 km of riverbank However one did not proceed due to sale of the property during the life of the project and at least two withdrew from their Funding Agreement, due to health reasons
Three landholders entered into conservation covenants which in total covered 63 hectares in the Inglis and Leven River catchments, which included 47 ha of Eucalyptus viminalis (White Gum) wet forest which is listed nationally as “critically endangered”
The final length of river frontage that was protected or enhanced across the six priority areas was 35 km
We have had good levels of interest from adjoining landholders, enabling us to ensure long reaches of river are protected In some instances, landholders have already fenced the river to exclude stock using previous funding programs or from their own resources but have undertaken weed control and/or revegetation under this funding program
Left and above left: Before and after weed control Control of weeds such as Blackberry and Willow in the riparian zone needs to ensure that native vegetation isn’t impacted and can regenerate naturally
In addition to works on the ground, a number of promotional products, media activities and field days were organised
A short video on the Giant Freshwater Crayfish Recovery Project has been produced with assistance from crayfish expert Todd Walsh and is available on our website https://www cradlecoast com/naturalresource-management/our-work/currentprojects/giant-freshwater-crayfish-recovery/
A postcard and poster were developed and distributed to retail outlets and visitor information centres and facilities, to advise users that it is forbidden to fish for freshwater crayfish in Tasmania and ways that they can help improve habitat The taking of freshwater crayfish was stopped in 1998 with high fines for those caught poaching today
The first a bus tour around the Inglis catchment in March 2021, which attracted 36 participants, despite inclement weather
The second field day for TAFE students undertaking a course in Conservation and Ecosystem Management at one of our project sites in the Detention
The third field day was at one of our larger project sites in the Duck catchment, where extensive willow control had been undertaken and riparian fencing and off-stream watering installed 37 participants enjoyed good weather and presenters demonstrated an improvement in the water quality and habitat since the inception of the project in 2020
Top Right: Field tour in the Inglis March 2021
Above right: TAFE field day in the Detention River catchment March 2022
Right: Field day on banks of Duck River April 2023
ia activities were undertaken as part of project ed project updates, full and half page advertisements on icle on the crayfish and some of our project activities in printed in the Tasmanian magazine 40 South ABC oject landholders in the Detention about works they had project to them
a Giant Freshwater Crayfish Reference Committee was North, to help guide the implementation of both projects e Committee was made up of representatives from key h as DPIPWE/NRET and Inland Fisheries, industry Timbers Tasmania, Tas Irrigation and Huon xperts from UTAS, and Kanunnah Pty Ltd Other ian Land Conservancy, OzFish and City of Launceston ce annually throughout the project and provided valuable project delivery
Under the project, landholders in the priority areas were eligible to develop a proposal for a conservation covenant to protect good quality Giant Freshwater Crayfish habitat, including surrounding native vegetation
A conservation covenant is a voluntary agreement between the landholder and the Minister administering the Tasmanian Nature Conservation Act 2002 Conservation covenants aim to protect and enhance the natural, cultural and/or scientific values of the area of land under covenant. The covenant is placed on the land title, to provide long term protection to the area even if ownership changes.
Conservation covenants are part of Australia’s National Reserve System and provide the highest level of protection for private land conservation.
Tasmania has over 900 conservation covenants protecting approximately 112,000 ha Each covenant is tailored to suit the property and is developed with the landowners based on a natural values assessment and the management requirements Conservation covenants provide landholders an opportunity to protect valuable Giant Freshwater Crayfish habitat on their land into the future
Some landholders have used this funding opportunity to develop proposals for conservation covenants on land with high quality GFC habitat and remnant vegetation on their properties, including riparian, floodplain and hillside forests
Three separate conservation covenants were approved in 2021-22 under the project, to protect 63 ha of land surrounding nearly five kilometres of high-quality Giant Freshwater Crayfish habitat in the Inglis and Leven River catchments An exciting benefit of these covenants has been the inclusion of 47 5 ha of Eucalyptus viminalis (White Gum) wet forest, listed nationally as “Critically Endangered” The covenants also protect habitat for a range of other threatened and non-threatened fauna and flora like Tasmanian Devil, Spotted-tailed Quoll and the Tasmanian Masked Owl The three covenants will become part of the National Reserve Estate and the areas will be protected in perpetuity, a great conservation outcome for Giant Freshwater Crayfish and other important natural values in north-west Tasmania The successful covenants were also able to access stewardship payments which will help towards maintenance work such as weeding, on the covenant area long term
The covenants were developed by the Tasmanian Land Conservancy, under contract to Cradle Coast NRM, with the individual landholders. The administrative process to approve and develop the covenant was undertaken by Natural Resources and Environment Tasmania’s (NRET) Private Land Conservation Program, who waived the administrative fees as part of their support for the project.
As mentioned, the habitat requirements for Giant Freshwater Crayfish vary depending on it's age. Juvenile crayfish prefer shallow, fast-flowing streams with bed materials such as cobbles and boulders that they use for shelter. Adults often move to slower-flowing reaches where they like undercut banks to burrow in or logs and boulders to seek shelter under.
Crayfish prefer well-vegetated streams with clear water and even, cool temperatures. In addition to providing shelter, in-stream logs and dead wood are critical for providing food. Vegetation along both banks of the waterway moderates temperature extremes and filters sediments from soil and effluent which would otherwise muddy the water and degrade crayfish habitat Without a ‘messy’ layer of fallen leaves, logs, stones, and branches, the Giant Freshwater Crayfish will be without an environment to live and breed
The land alongside your waterways is probably your property’s most productive, thanks to its deeper soils and higher moisture content, but it is also the most vulnerable to damage from stock impacts and flooding impacts Riparian areas are easily damaged by stock that eat and trample the vegetation, destroy soil structure and release effluent in and around the waterway Without vegetation on the batters of the waterway and on top of the high bank, the riparian land is susceptible to bank erosion and slumping in times of high flow or flooding
Sedimentation in the waterway from erosion and animal access can cover the crayfish habitat in silt, sand or gravel and the lack of vegetation on the banks reduces the shading impact and increases the temperature of the water, which doesn’t suit the crayfish
A good mixture of native vegetation – trees, shrubs and groundcover - is essential to provide stability to the waterway banks as well as providing habitat for the animals (large and very small) that rely on our waterways too Diverse riparian vegetation with density and structure can slow the flow of the water and armour the banks Riparian vegetation also helps filter out the nutrients and sediment contained in runoff, which reduces pollution of the waterway leading to excess algae growth and water weeds
Isolated trees or sparse vegetation does not adequately protect the banks and batters of the creek from erosionGood riparian vegetation has a number of layers and goes from the edge and across a buffer area on the high bank.
Naturalregenerationmay occuroncestockandgrazing areexcludedfromthe waterwaybutinsome instances,revegetationor replantingofparticularspecies mayberequiredtoo For example,maturetreesmaybe presentbutnoshrublayer,so infillplantingmaybe recommended,particularlyif seedbankshavedisappeared asaresultofprevious management.
Excludingstockisagreatfirst stepinprotectingyourriparian area,butyoucannot“lockitup andleaveit”.
Just like other productive areas of your property the riparian land needs ongoing management. Weed issues are probably the most common ongoing management issue, as well as things like pest animals, stabilising erosion areas, or slowing the flow of water. It is essential to keep on top of the weeds as soon as they emerge so that they don’t outcompete your plantings or your natural regeneration. The first two or three years after fencing are probably the most critical, after which your native vegetation should be able to out-compete the weeds. The Giant Freshwater Crayfish Project has worked with adjoining neighbours in particular sub-catchments to try and ensure a coordinated response.
Finally, improved riparian management provides public as well as private benefits, and can impact landholders and water users both upstream and downstream of the area improved
A multi-storey canopy on the Upper Leven River catchment
Baseline monitoring was undertaken in all six priority areas before any project works were implemented This, combined with monitoring undertaken at the end of the project, helped identify any changes or improvements that may have occurred in this stretch of river over the life of the project Many of the project works, such as revegetation, will take many years to become established and should provide longer term benefits such as re-introduction of timber into the river and moderating the impacts of heat waves This will require longer term monitoring, beyond the life of the project End of project monitoring was undertaken in Spring 2022 and Autumn 2023
As part of the baseline and end of project monitoring, both juvenile and adult crayfish were captured in the priority areas, with the larger specimens tagged The presence or absence of juveniles and adults was noted at each site Giant Freshwater Crayfish can be found in low numbers in many poor-quality sites; however, the densities increase rapidly in sites with excellent habitat Adults were measured, weighed, and tagged before being released back into the same spot they were trapped Sampling information was collected and is recorded in a state-wide database
Left: Same male trapped again in 2022. He had moulted and grown an additional 11 mm and was 300 g heavier than in 2020. Photo credit: Todd Walsh
Far left: Todd Walsh checking for a tag in an adult crayfish.
Future monitoring will involve trying to use in-stream microchip readers to monitor the movement of these tagged adults or to recapture tagged animals and measure growth rates over time. Due to the different habitat requirements of juvenile versus adult Giant Freshwater Crayfish, a number of sites along a reach might have been sampled. For example, juveniles prefer the faster flowing and shallower areas of the stream, whereas adults prefer well-shaded, flowing parts of the stream with deep pools, decaying logs and undercut banks.
The AUSRIVAS sampling that was also undertaken as part of the baseline and end of project monitoring, uses aquatic macroinvertebrates (animals without backbones that can be seen with the naked eye such as mayfly, caddisfly, dragonfly larvae and shrimps) as biological indicators of river health, and will also provide the means to measure changes in water quality over time.
Prior to the finalisation of the six priority areas at the beginning of the project, a social survey was undertaken by external provider Myriad Research, to provide an independent assessment of community attitudes in relation to the management of threatened species, and in particular the Giant Freshwater Crayfish. Respondents were selected at random across the region and owned or leased land of more than two hectares. The majority of respondents (92%) knew that the crayfish was a threatened species, but time and age and to a lesser extent cost were identified as major influences on getting involved in conservation activities
Above: Adult male crayfish trapped in October 2020, tagged and released.
Poaching of crayfish, particularly larger breeding adults can lead to the loss of localised populations
Under Inland Fisheries legislation poaching of the Giant Freshwater Crayfish is illegal and can attract fines of up to $10,000 and up to $105,000 and/or a year in prison under Tasmanian Threatened Species legislation.
In addition, the taking of any crayfish (including the other two species of Astacopsis) is prohibited under Inland Fisheries legislation. It is also illegal to take yabbies (Cherax destructor, an introduced species in Tasmania).
Members of the public and landholders are encouraged to report evidence of poaching of Giant Freshwater Crayfish via email to the Inland Fisheries Service at infish@ifs.tas.gov.au or call 0438 338 530 or Crime Stoppers on 1800 333 000.
When poaching sites are identified, Inland Fisheries can then monitor sites or install camera monitoring points.
For more infomation contact:
Fiona Marshall
Agriculture Project Coordinator
Phone: 03 6433 8433 Mobile: 0413 382 390
Email: fmarshall@cradlecoast.com
Website: www.cradlecoast.com
