Are Central North burrowing crayfish really so few in number - and are they still declining?
Previous efforts to map out Central North burrowing crayfish burrows found them very thinly scattered through their range, occupying a total area of less than 100 hectares! - and that this was shrinking!
Burrowing crayfish can be detected by the openings of their burrows, often marked by a chimney of excavated pellets. Most of our approximately 33 species live nowhere but Tasmania - and the Central North burrowing crayfish can only be found between the Don River, Narawntapu and Sheffield.
Much of this area is made up of privately owned properties - so, to find out exactly what's happening to the species, the information is needed from many different people.
• A detailed map of areas where Central North burrowing crayfish definitely are and definitely aren’t – together with a decreasing set of areas where this information isn't yet available.
• In future: an approximate but still meaningful population estimate of how many Central North burrowing crayfish there are in the world.
This information will help confirm details of the species’ threatened status (currently Endangered on the state and federal lists, and Critically Endangered on the IUCN Red List) - and also set a baseline for its conservation. Over time, together we can monitor whether we are succeeding in protecting the species and helping it recover, or whether its distribution and numbers are continuing to decrease.
Tell us about your area
Are there any crayfish burrows in your area? Whether you have lots or none, and even if they're unlikely to be Central North burrowing crayfish, you can ultimately help improve the maps for all species. Fill out this questionnaire. Record what you've seen, or perhaps invite a detailed survey in future by volunteers.
You can also record what you've seen on the smartphone app iNaturalist. Upload the app (it works for both Android and iPhone), and join the iNaturalist project 'Claws on the Line'.
Follow the instructions to record your observations to the project and ensure that everyone's privacy is respected. Precise locations of crayfish chimneys will not be shared elsewhere without your permission.
Help with more surveys
Some landowners are inviting Claws on the Line to thoroughly survey their land, so that we can map Central North burrowing crayfish locations in detail. Could you lend a hand? Provide your details in the questionnaire.
Would you like your school to get involved? Our Expedition Class trials have been very popular! Or would you like a community workshop? Let us know via the questionnaire.
What’s a burrowing crayfish?
Usually all you see of a burrowing crayfish is the opening to its burrow – a 2-5 cm diameter hole in the mud. Below the surface, however – sometimes a metre or two below, depending on how far it needs to burrow to reach the water table – is a little crayfish.
Often the hole is easy to spot, as it’s surrounded by a ‘chimney’ made out of the burrowed mud from the hole, which can be anywhere from barely noticeable to more than 30 cm high. On the other hand, it may still be hard to see if it’s hidden by vegetation such as ferns or blackberries.
Get other information
Can you recognise a species by its burrow? How many different burrowing crayfish species are there in Tasmania? What does it mean if I have them on my land? Answers to all this and more are on our FAQ
Spread the word
Print out this information on Claws on the Line, and share it with friends!