Australian Aquatic Biological

Australian aquatic biodiversity research and consultancy

The Narrow Dwarf Crayfish Euastacus angustus

Photo Euastacus angustus

The Narrow Dwarf Crayfish Euastacus angustus

A new Euastacus species has been described from NSW. Jason Coughran and Kathryn Dawkins have described the new species from the Border Ranges National Park of north eastern, NSW. It is a dwarf species that is cryptic in nature and seemingly exceptionally rare.

Photo Euastacus angustus

The Narrow Dwarf Crayfish Euastacus angustus

The species is described from just one specimen collect in 2002 by Jason and he has never found another since. Then back in 2010 during routine biological surveys as part of the Australian Crayfish Project, Paul Van der Werf and myself found a solitary specimen and to the best of our knowledge these are the only two specimens in existence. At this time that makes this species the rarest Euastacus species in Australia.

The narrow dwarf crayfish Euastacus angustus

The narrow dwarf crayfish Euastacus angustus

It is very similar to other dwarf crayfish species found in the region except it has a laterally compressed carapace giving it the narrow or slender look and a small expodite on 3rd maxilliped. The specimen in the photos are of a male 11 gram in weight and 28.02 mm OCL, this represents the largest specimen on record. To date no females of this species are recorded.

The Sydney Crayfish Euastacus australasiensis

 

The Sydney Crayfish Euastacus australasiensis

The Sydney Crayfish Euastacus australasiensis (this old man crayfish is heavily covered in commensal worms)

Surveys in April 2013 of creeks in the Blue Mountains of NSW in partnership with Blue Mountains City Council have been very productive. Among other species we have been researching the Sydney Crayfish Euastacus australasiensis from the Leura area.

Euastacus australasiensis

Euastacus australasiensis

Euastacus australasiensis is a protected crayfish and it is illegal to have one in your possession. They are only for looking at and photographing rather than collecting and eating. Overfishing, illegal collection and translocation of invasive species are usually a result of lack of knowledge-people just have no idea they are doing anything wrong. Better education of general public is what’s needed and we will continue to strive towards better education.

Leura Falls Creek

Leura Falls Creek

We found them to be abundant in the local streams and our research increased the knowledge base on the species. Previously the largest specimen we the Australian Crayfish Project had on record was 130 gram and 60 mm OCL. That was just larger than that recorded by Morgan (1997) at OCL of 59.4 mm OCL.

From Leura Creek we recorded an Euastacus australasiensis of 143 gram and 64.75 mm OCL. That’s a new record for the Australian Crayfish Project for now, but we know from the size of the burrows we have seen that larger individuals must occur. The trouble is that these huge adults are 20 plus years old and some indications they may be over 50 years old. They have been just too smart to be captured by us (hopefully we will get smarter or luckier and catch a monster).

Conservation of Imperiled Crayfish, Euastacus dharawalus

 

The Fitzroy Falls Crayfish Euastacus dharawalus

The Fitzroy Falls Crayfish Euastacus dharawalus

Our conservation paper on Euastacus dharawalus has been published in the Journal of Crustacean Biology which is published by The Crustacean Society. This is the second conservation paper I’ve published with them and hopefully we will do many more in the future. For the last 30 years the Crustacean Society has published four journal issues per year, but since 2012 they are doing 6 issues per year. They are a non profit organisation and I’m a happy member who recommends if you have an interest in crustaceans you should join.  www.thecrustaceansociety.org/  The mission of the Crustacean Society is to advance the study of all aspects of the biology of the Crustacea by promoting the exchange and dissemination of information throughout the world. This latest paper is titled:

McCormack, R.B. 2013. Conservation of Imperiled Crayfish, Euastacus dharawalus(Decapoda: Astacidea:Parastacidae), from the southern highlands of New South Wales, Australia. Journal of Crustacean Biology, 33(3), 432-439, 2013.

Conservation of Imperiled Crayfish Euastacus dharawalus

Conservation of Imperiled Crayfish Euastacus dharawalus

Members receive online access to Ecdysiast plus online and print version of Journal of Crustacean Biology.

This was an important paper as the New South Wales Fisheries Scientific Committee has listed Euastacus dharawalus as Critically Endangered. This is the first Euastacus crayfish to be listed as critically endangered by any state or the federal Government. It is illegal to catch and keep, buy, sell, possess or harm Fitzroy Falls Spiny Crayfish (Euastacus dharawalus) without a specific permit, licence, or other appropriate approval, and significant penalties apply. For critically endangered species, these penalties can include fines of up to $220,000 and up to 2 years in prison (Fisheries NSW).

Fitzroy Falls plunging 80 m into the valley below

Fitzroy Falls plunging 80 m into the valley below

Euastacus dharawalus has a very restricted distribution only known to occur above the Falls. If you are one of the 300,000 visitors/year that visit the walks and viewing platforms above Fitzroy Falls then take the time to have a look in the creek. If you’re lucky you may see one of these critically endangered crayfish scavenging along creek bottom.

The Giant Spiny Crayfish (Euastacus spinifer) from the Blue Mountains

The early morning view from one of the lookouts at Wentworth Falls

The early morning view from one of the lookouts at Wentworth Falls

A quick survey of some of the mountain streams in collaboration with Blue Mountains City Council proved most enlightening. The local streams draining through suburban areas seemed to have abundant numbers of freshwater crayfish and fish. We were very satisfied with the aquatic health of the streams we surveyed and following is a precis of the main species we encountered in abundance.

Photo Euastacus spinifer

Photo Euastacus spinifer

Euastacus spinifer is a Giant Spiny Group Crayfish was abundant in the Wentworth Falls area. They are a giant species that grow to a huge size of 1 kg or more and can have spectacular colours. The adults prefer the permanent clear flowing sections of streams and rivers and are active both day and night and can generally be seen wandering the creeks during the day, especially mid-afternoon onwards. In the clear mountain streams if you are quiet and patient you will see them wandering along the creek bed forever in search of tasty morsels.

The Giant Spiny Crayfish Euastacus spinifer

The Giant Spiny Crayfish Euastacus spinifer

Also in the same stream were large numbers of native fish. Both the Mountain Galaxias Galaxias olidus and the Australian Smelt Retropinna semoni were abundant in the streams with schools of 100 fish very common.

The Mountain Galaxias Galaxias olidus

The Mountain Galaxias Galaxias olidus

The Australian Smelt Retropinna semoni

The Australian Smelt Retropinna semoni

 

 

 

 

Engaeus sericatus from south western Victoria

 

Engaeus sericatus from the Gellibrand River drainage

Engaeus sericatus from the Gellibrand River drainage

Engaeus sericatus is a small burrowing crayfish from the lowland regions of western and south western Victoria. We found most of our specimens along the edge of the rivers and streams or in small seepages and creeks. As a species it seemed locally abundant at most sites we surveyed, the sites where areas that water seemed permanent and all the burrows had water filled chambers at the bottom. Burrows did not seem to extend far away from the streams into the forest floor and most burrows seemed relatively rudimentary with only 1 or 2 surface entrances down only 500 mm to small water filled chamber.

Small roadside drains/seepages had very high populations of bothe Engaeus sericatus and Geocharax gracilis

Small roadside drains/seepages had very high populations of both Engaeus sericatus and Geocharax gracilis

Engaeus sericatus is found in sympatry with a number of different species. We found Geocharax crayfish within 50 mm and Euastacus bispinosus, Euastacus yarraensis, Cherax albidus and Engaeus fultoni all within 1 metre of the species. Commonly we found that Geocharax crayfish also seemed to prefer the same habitat and at many sites we found them both together at relatively high densities of 2-3/m2 for each species.

Geocharax gracilis from the lower Gellibrand River area found living beside Engaeus sericatus

Geocharax gracilis from the lower Gellibrand River area found living beside Engaeus sericatus