In 2017 the Hunter Region of NSW was suffering from the worst drought in 50 years. In late 2017 my local creek at Port Stephens dried up for the first time in the last 18 years since I’ve been here.
As the water dried out, I took the opportunity to investigate all the species that occur in my creek. The shallows of the creek dried rapidly but the deeper pools retained water through most of the 2017 period.
Interestingly, I observed freshwater mussels moving from the shallows into the deeper water. They use their foot which is tongue like to push themselves along. This leaves a trail in the sediments which you can easily follow to the mussel.
I was quite surprised by the sheer number of them that were in my deeper pool that I would normally use as a fishing and swimming hole. Typically its over 3 metres deep but the drought saw it shallowing to less that 300mm. Freshwater mussels are great indicators of your streams health. They are sensitive to pollution and sedimentation so if you have healthy populations, your stream is more than likely healthy.
The water in the bottom of my pool was clear, warm and shallow so I decided to survey the freshwater mussels in it. I systematically, worked my way by hand through the bottom sediments, feeling for mussels and counting them.
Interestingly, I found around 2600 mussels in the pool. That’s great news and indicates my creek is generally health and has been so for quite some time. Mussels are very long lived 20-40 years and these were a good mix of small to large old mussels that I was finding, indicating healthy conditions for many years.
Unfortunately, I’m not a freshwater mussel expert but I have spent some time over the years with experts helping them collect mussels for identification. The mussels I found were all very similar in size, colour and shape. However, if you looked closely, occasionally, I would find something different.
The most common and abundant freshwater mussel was Hyridella drapeta.
Interestingly, in amongst the 2600 mussels were around 160 different ones, these were Hyridella australis.
They look very similar but if you look closely they have v-shaped sculpturing on the beaks of the shells.
Freshwater mussels are natural biofilters processing large volumes of water. They remove large quantities of nutrients, algae, bacteria and organic matter which helps to clean water bodies. Both H. australis and H. drapeta are classed as river mussels. They need permanent and flowing water to breed and survive so generally found in permanent flowing streams.
Many people want freshwater mussels for their fish ponds or farm dams to help keep them clean. River mussels are not suitable and will eventually die in a static water dam or pond. However, there is one species that thrives in static water dams and ponds. That’s the flood plain mussel Velesunio ambiguus. This mussel will live and breed up to huge numbers in your ponds and helps to keep your water clean. This is a commercially, cultured species so available for purchase from aquaculture farms like AustSilvers or if you just want one or two for a fish tank then check with your local aquarium shop.
BTW, If you want to start a sustainable population going in a farm dam you will need several hundred as initial stock.
Freshwater blood and fluid sucking leeches can pose a serious problem for freshwater crayfish. Typically it’s the common yabby (Cherax destructor) that you find leeches attached to or they have a nasty round scar indicating a leech has had a feed. The scar remains until the crayfish moults but the scar itself can create difficulty in moulting and can lead to the death of the crayfish. From an aquaculture perspective, leeches in your ponds are a big NO-NO and every effort should be made to catch and remove them as the unsightly scars on crayfish make them unsellable.
Most leeches can ingest several times their own weight in blood at one feeding and swell to a large fat size. Leeches attach to their hosts and remain there until they become full, at which point they disengage and fall off to digest their huge feed. Crayfish are most vulnerable when they are freshly moulted. Freshly moulted crayfish are already stressed out and weakened by the moult process, the additional blood loss from a leech feeding could be fatal. This risk of mortality is greatly increased if the crayfish is small and the leach large.
The example Marron with a leech attached was found in the swimming hole below North Dandalup Dam, WA.
Images compliments of Tegan & Josh Moylan
SORRY – THIS SYSTEM HAS BEEN SOLD
A complete fish hatchery and grow out recirculating aquaculture system is currently for sale. If you are thinking of entering the Recirculating Aquaculture Industry and can’t afford the $500K price tag for a brand new system, then purchasing a second hand system at 30% of the new price may be the perfect option for you.
Second hand systems coming on the market are rare so you need to act quickly when they do come up. Now due to retirement of the owners a complete RAS system is currently offered for sale.
The system belongs to Glencoe Fish Hatchery (GFH) which supplied weaned pellet feeding Murray Cod fingerlings to other RAS grow-out systems of the commercial aquaculture industry, plus grown out Barramundi for the restaurant and market trade in Melbourne. All fingerlings produced in the RAS by GFH came with a veterinary certificate to guarantee their health. Glencoe Fish Hatchery are proud to be one of the first hatcheries to have inside brood stock of Murray Cod which guarantees when they breed, their offspring will be of a high quality and health standard as the internal brood stock are not live caught but born and bred in tanks which means their natural instincts have changed and they live wholly on a pellet feed diet.
Glencoe Fish Hatchery was aimed at the commercial market with the system’s capacity around 100,000 fish per batch and several batches per year. Glencoe Fish Hatchery strived to have the best fish on the market in both health and appearance.
The complete system as a single unit is for sale.
The system is currently intact and complete available for viewing. The owners will dismantle and make it ready for transport by the purchaser. Each section would be labelled ready for reassembly by the purchaser.
For Further Information Contact: Andre Henry Phone: 0427 640 844 Email: email@example.com All equipment is viewable by appointment only, at: Glencoe Fish Hatchery 2333 Loddon River Road, Appin South Victoria 3579
Research Project 100007 initiated in 2008 has finally been completed. This project has been ongoing for the last 10 years, but has at last culminated in the publication of a description of a NEW Euastacus species for the western drainage of New South Wales, Australia.
The Cudgegong Giant Spiny Crayfish Euastacus vesper is described from the upper reaches of the Cudgegong River, east of Kandos NSW. The description was published in May 2017 in the international journal Zootaxa.
Euastacus vesper sp. nov., a new giant spiny crayfish (Crustacea, Decapoda, Parastacidae) from the Great Dividing Range, New South Wales, Australia ROBERT B. MCCORMACK & SHANE T. AHYONG DOI: https://doi.org/10.11646/zootaxa.4244.4.6
This new species seemingly has a very small distribution and faces a large range of serious threats. The next Project will to systematically survey the surrounding area and accurately define the exact distribution of the species and then publish a paper of its conservation status, something we consider based on the available information, would be “Critically Endangered”.
Research Project 100084 has been generated to designate a conservation status for this new Euastacus species.
For another article on E. vesper, see:
This species is endemic to Victoria with a relatively small distribution known at this time (estimated extent of occurrence of approximately 200 km2). Found in the upper Yarra, Acheron, Yea and Big Rivers. An area roughly from Kinglake to Eildon to Jamieson to Noojee to Hoddles Creek. Central Highlands Burrowing Cray Engaeus affinis has been assessed on the IUCN Red List as Data Deficient.
It’s a robust species and at many sites relatively abundant. Typically, it’s a communal burrower, both type 2 & 3 burrows with multiple surface entrances (20 or so) over a square metre. Both fans shaped entrances and chimneys. Surface openings descend into large central burrows. Central burrows are relatively large in diameter (150 to 200 mm), typically water filled and tending horizontal and descending and converging into a larger chamber.
Typically, the easiest way to capture is to excavate down to the water level, usually from 200 to 600 mm deep. Once water is found, wait, (patience required), larger males will come to investigate the disturbance and you can grab them, otherwise, every 5 minutes or so, shove your hand down the burrow and feel around in the water. If you are lucky and have good feeling in your fingers you should be able to grab one every 5-10 minutes. That’s the way we collected the specimens for this article.
Those from Healesville were in a yellow clay on the slope beside a creek approximately 1.2 metres above the creek water height (7 metres from creek bank) but had water at 650 mm in the burrow system. Those from Badger Creek were in a fine silty material in a seepage area in the tree fern forest with water only 100 mm below ground level and over 100 m from Badger Creek.