Tasmanian giant freshwater crayfish
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| Astacopsis gouldi (Clark, 1936) |
The Tasmanian giant freshwater crayfish is the largest freshwater invertebrate in the world. The species in only found in Tasmania, and is listed as a vulnerable species due to habitat loss and over fishing. It is also severely threatened by siltation and de-snagging of streams as decaying wood forms the favourite part of its diet. It is not known if the animals are nourished by the wood, the bacteria, algae or invertebrates living in the rotting logs. They also eat leaves, fish and other meat including other lobsters. They are territorial.
Individuals of over 5 kg in weight and over 80 cm long have been known in the past, but now, even individuals over 2 kg are rare. The species is only found in Tasmanian rivers flowing north into the Bass Strait (with the exception of the Tamar) below 400 m above sea level. The specific epithet gouldi commemorates the Australian naturalist John Gould.
A. gouldi is very long-lived, 40 years. Their main predators are humans, platypus, river blackfish and water rats. It reproduces slowly, with the result that unregulated recreational fishing of this species has had a great impact on its abundance, and also explains why the largest individuals now found are smaller than previously. This species was listed as "vulnerable" under Australian law, in 1995 and it is now illegal to catch A. gouldi without a permit, carrying a maximum fine of AU$10,000.
[edit] Interesting facts:
- Males maintain a harem of several females
- They can regrow lost limbs
- Their blood is clear, turning blue on contact with oxygen
- They moult in December/January and the hormone that prevents continuous moulting is found in their eyes
- They can survive out of water for sometime if it is not too hot or windy
- Calcareous gastroliths can be used to age a deceased crayfish
[edit] References
- Crandall (1996). Astacopsis gouldi. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Listed as Endangered (EN A1ace, B1+2abce v2.3)
- Inland fisheries, fact sheet
- "Giant freshwater lobster - protecting its future" Inland fisheries service publication
- "Wet Ones - the giant freshwater crayfish" information sheet, Dept. Primary Industry and Fisheries, Tasmania
- Flowerdale Lobster Haven, Tasmania
