False spider crabs Amarinus lacustris are a widespread and relatively abundant small crab species inhabiting low salinity and freshwaters waters in south eastern and eastern Australia, New Zealand, and Lord Howe and Norfolk Islands. They are a small freshwater crab species only reaching 10 mm in body width, with a distinctive H-shaped groove on their back. They are a slow growing species that can be covered with weeds or algae growing on their shell which makes them harder to see and for predators to find. It’s a small vulnerable species that is cryptic in nature and rarely seen or captured, spending most of their life hiding in thick reeds and roots or under rocks that offer protection and shelter from predators. Though widespread and when present they can be abundant (the ACP has found them at over 100/m2) they are a cryptic species that makes finding them difficult. The knowledge base on this species is relatively small, additionally, little has been done on the taxonomy and genetics of this widespread crab species and it is currently proposed that the current description may in fact represent three or more distinct species.
The ACP is intensifying research on this species and continues to collect specimens from across Australia. As we collect more specimens we are getting to know their habitat preferences and it’s becoming easier and easier to find these elusive creatures.
We have finally finished our aquatic surveys of the lower Clyde River, NSW. It’s an exciting area with mostly pristine clear flowing streams full of aquatic life. The results of the survey have been extremely interesting and have resulted in some significant findings. We have identified 3 different freshwater crayfish species in the lower Clyde River and they all match the known descriptions for all three species. Interestingly, the specimens of Euastacus crayfish previously collected from the upper Clyde are generally morphologically different to those in the lower Clyde. Eventually we will get the genetics done on all the specimens collected and then work out whether the upper Clyde specimens are a morphological variation or a separate species. Stay tuned for further updates. The full results of the aquatic biological surveys will be complied into a report and issued to the Southern Rivers Catchment Management Authority.
We surveyed 57 sites and at 43 of those we captured freshwater crayfish. A total of 149 Euastacus yanga were captured, examined, weighed, measured, and released during this survey. Euastacus yanga has the third largest distribution of any Euastacus species in Australia after E. spinifer and E. armatus. Found in south-eastern New South Wales from Robertson all the way south to north-eastern Victoria. It’s distribution extends from the Shoalhaven River in the north, then south through the Clyde, Deua, Tuross, Brogo, Murrah, Bega, Towamba, Womboyn, Wallagaraugh and Genoa rivers, as well as all the smaller coastal rivers and creeks running into all the inlets, lakes and bays down the coast. Found from 50 m to 895 m a.s.l it is a widespread and abundant species.
We observed Euastacus yanga to commence breeding in mid May in water temperatures between 11.3-12.1°C. The berried females nurtured their eggs and young till mid November to mid December when they released their brood into the streams. A huge amount of information was gathered as part of the surveys and this will be compiled into a peer reviewed scientific manuscript.
Whilst surveying a coastal stream near Batemans Bay last week, I was sprung by the local Fishing Inspector. I was extremely happy that a passing Fisheries NSW officer saw me near a creek and took the time to bail me up and see what I was doing. I had all the correct permits and was OK but let that be a lesson to all those that are thinking of doing the wrong thing in NSW, Fisheries NSW inspectors are out there actively looking for those doing something they shouldn’t, you will get busted, so do the right thing.
If you see something occurring that’s wrong then let your local Fisheries inspector know and they will take action.
My congratulation to Fisheries NSW, it’s reassuring to know they are actively out there patrolling the creeks and streams, protecting our native crayfish and fish, ensuring the fisheries laws and regulations are obeyed.
A Guide to Australia’s Spiny Freshwater Crayfish wins a coveted Whitley Award. The winners were announced by the Royal Zoological Society of NSW at a ceremony held in the foyer of the Australian Museum in Sydney on Friday 11th of October 2013. The Whitley Awards are for outstanding publications dealing with the promotion and conservation of Australasian fauna.
We were successful in receiving an award for our latest book. A Guide to Australia’s Spiny Freshwater Crayfish published by CSIRO Publishing was awarded a Certificate of Commendation for Best Book in its Category, Invertebrate Guide. This was a great honour and we thank all those that nominated the book and voted for it to win the award.
To purchase a copy go to: http://www.aabio.com.au/products-page/
Membership to the Crustacean Society in now due. I’m a member and recommend if you have an interest in Crustaceans you should also join up. The mission of the Crustacean Society is to advance the study of all aspects of the biology of Crustacea by promoting the exchange and dissemination of information throughout the world.The Crustacean Society publishes The Journal of Crustacean Biology with free access to members. For the last 30 years they have published four issues per year, but since 2012 they have been publishing six issues per year. Check out the website http://www.thecrustaceansociety.org/ and join up.