Australian Freshwater Crayfish Project

Australia has a vast variety of native freshwater crayfish, but many are closely related and it is very difficult to distinguish different species. More are being identified all the time, plus better identification and DNA testing is removing some of the previously misidentified species.

The Australian Crayfish Project is a privately funded project to identify, classify, photograph and supply a ready identifier for all the Australian Crayfish species. The culmination of this project will be a full colour Field Guide of all species with high definition colour photos and clear identification keys.

All Australian crayfish belong to the family Parastacidae. Australia as a whole has the three largest species of freshwater crayfish in the world. The largest is the Giant Tasmanian Crayfish – Astacopsis gouldii, followed by the Murray Crayfish – Euastacus armatus, and then the Western Australian Marron – Cherax cainii, (Cherax tenuimanus). Not far behind these are the many species of Euastacus crayfish found in NSW, Queensland and Victoria that grow to 1,000 grams plus.

Across Australia there is a vast diversity of different species of crayfish. These crayfish have developed over the last couple of million years and, though as a rule these species do not interbreed, they do in many instances co-exist with each other. It is not uncommon to find 2 or even 3 different species living in the same drainage basin or sharing the same habitat.

As a general rule, the different species of crayfish have developed individually due to four distinct factors. These are geographic barriers, water availability, temperature and predators. There has been, over the years, a lot of concern about introducing species of crayfish from one area and those crayfish escaping into the wild and taking over from the native species. Though this is always a concern, however, unless all the four criteria are met, then a non-indigenous species will not survive.

The majority of Native Australian species have very specific environmental requirements and will not survive outside those narrow limits. This is an extremely worrying fact that will have dire consequences for many Australian species of crayfish as we enter a period of continental-wide climate change. A few of the Australian species, like the yabby Cherax destructor, have extremely wide environmental tolerance limits and this makes them very dangerous as they can survive just about anywhere on the planet.

All these species can be very similar in appearance to other related species. All the species have different colour variations and many have morphological differences between populations. Add that there are differences in appearance between juveniles and adults and that all adds up to one enormous identification difficulty. The Field Guide to the Freshwater Crayfish of Australia will help alleviate this problem.

There is a desperate need for a guide of this type, so many people catch freshwater crayfish as pets yet are unable to identify the species they have captured so are unable to look after them in the required manner and they eventually kill them. Additionally, with the trade in Native species increasing worldwide, there is a desperate need for a ready guide to identify species for Fisheries and Customs personnel.

This survey is also identifying previously unidentified and undescribed species – this in itself is an essential task. Many of the unidentified species are endangered and will not be considered in developments as they are unrecognized as endangered species. By identifying them and notifying the authorities of their existence may see their continued existence.

The Australian Crayfish Project is a long term project that was started in early 2005 and is not due for completion till late 2010 when the Field Guide to The Freshwater Crayfish of Australia will be completed. Stage I is a Field Guide to the Freshwater Crayfish of NSW and this is due for publication early 2007.

Additionally, any information you may have on unusual crayfish species in your area would also be appreciated. This project is being helped by researchers, university staff, National Parks Officers, aquaculture association members, crayfish enthusiasts and the general public.

Over the last 20 years plus as a crayfish farmer, TAFE lecturer, President of the Aquaculture Association, and author of various crayfish books, I have had the privilege of meeting and talking to a vast number of crayfish researchers and fellow enthusiasts from around the world.

Over the years I have taken in every hint and comment about weird or unusual crayfish from around Australia and recorded them in a journal. Now, with 25 years of information on locations and species to check out, I am slowly checking them all.

So far I have discovered three confirmed new species currently undescribed, and another two suspected to be new that are awaiting DNA testing. I have only just started, who knows how many others are out there and what will be discovered over the next two years. If you have something unusual in your area let me know and let's get together and check it out.

Rob McCormack

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