YABBY INFORMATION

 

THE YABBY - Cherax destructor

Rob McCormack

.

The Yabby is a freshwater crayfish native to Australia.  Also known as a crawchie, crawdad, craybob or even lobbie, it's all dependent on where you come from.  Yabbies as a name can refer to any number of different crayfish species (small smooth shelled species) but as a rule it generally refers to Cherax destructor. This species is a native of the Murray Darling system (west of Great Divide – eastern states) and has the broadest distribution of any species in Australia.  In fact the yabby Cherax destructor is one of the few species other than man which is increasing its distribution across the planets surface.  Unfortunately, it is an invasive species and is becoming established along the eastern drainage of Australia in streams that it is not endemic to.  The repercussions of this and the effects to the native crayfish species and animals that live in these streams are unknown.

 

Yabbies are also known as the western blue claw yabbies, basically because they mostly have blue claws.  Yabbies can be any colour blue, black, white, brown, red, green or any combination, they will change colour to that which is most suitable for camouflage in the wild.  Yabbies grow to a maximum size of 350 gram, however, the common large size is 120 – 150 gram.  Yabbies have a life span of only 5 – 7 years under average conditions, in the wild their life expectancy is much shorter as they are towards the bottom of the food chain and a vast amount of animals consume them.  Some of their main predators are insect larvae, fish, eels, turtles, birds and water rats.

Aquarium Pets – Yabbies make great aquarium pets, they are easy to fed and keep without any problems compared to fish.  They eat any of the sinking fish food plus meat, fish, fruit and vegetables so just about anything.  They have gills just like fish so breath oxygen from the water so must be kept in the water just like a fish.  Fill the tank completely with water, they do not need to get out of the water unless the water goes bad.  An aerator or filter in the tank will keep your water fresher longer.  Usually you don't have to change the water until it becomes smelly. Water quality is directly related to the amount of food placed into the water, most people kill their yabbies with kindness, they place too much food in the water and it is not eaten so goes rotten, polluting the water.  For further information check out “Keeping Pet Yabbies” or go to www.rbmaqua.com.au to purchase.

Farm Dams – Yabbies are great for farm dams as they don’t need anything except a good dam.  Yabbies thrive in farm dams.  Best dams are those without large numbers of predators in them, i.e., fish, eels, turtles, etc.  Also best results will be in very turbid (Muddy ) dams, yabbies don't like clear water.  Average farm dams produce 50 - 100 kgs of yabbies per year without any effort.  To stock your dam use dam stock breeders 50 - 100mm head to tail, these are yabbies large enough to look after themselves, too large for most predators to eat and ready to breed.  Minimum required to start a population is 100, maximum is 1,000.  The more you put in the greater your chances of successfully starting a viable population.  Technically you only need two to start a population, one male and on female, however the chances of something happening to one is high.  Plus the chance of that boy finding that girl in the dam again is astronomical.  Best results are achieved by stocking with a minimum of 100 yabbies. No feeding required, yabbies eat grass, leaves, seeds, whatever blows or washes into the dam plus whatever grows in the dam, weeds, algae, insects, worms, etc.  You can capture them via meat on a string or commercial yabby traps.  To buy yabby  traps go to www.rbmaqua.com.au

Commercial Aquaculture Farms – You do not need any permits to grow yabbies for your family and yourself, however, if you want to sell yabbies then you will need an aquaculture permit from your states Fisheries Department.

Yabbies grow well in farm dams and some commercial aquaculture operations are extensive farm dam harvest operations where yabbies are just trapped from farmer’s dams.  If you have a group of farmers with lots of farm dams full of yabbies then this is a viable option.

Generally most commercial farms are located on rural properties in specially designed yabby ponds.  Commercial yabby farms consist of large numbers of shallow ponds designed specifically for the yabbies.  This maximizes the growth and numbers of yabbies that the pond produces.  It also allows for easy management and less costs in construction and ongoing maintenance.  For all you need to know on commercial yabby farming purchase “The Commercial Yabby Farmer” a 250 page book.  www.rbmaqua.com.au

Commercial farming is generally conducted either as extensive or intensive farming.  Extensive is where the yabbies basically fend for themselves with little in the way of management or food added.  The yabbies just live and breed in the pond and the farmer just catches them out with traps.  Production is low to medium and all production is based on pond surface area.  A hectare is 10,000 square metres in size and it is hectares that commercial farmers use to talk production.  For example a pond that is 20m x 50m is 1000m² so is one tenth of a hectare.  Good production by extensive methods is 800kgs of yabbies per hectare.  Therefore our 20m x 50m pond can produce 80kgs of yabbies per year.

Intensive yabby farming is where a greater level of management is used to produce larger numbers of yabbies.  This involves stocking ponds at optimal levels, feeding and protecting the crop and using good genetic stock.  This type farming will produce higher levels of crayfish at 2500kgs per hectare per year but at a lot higher cost in food and labour, etc.  Yabby farming is something that you can do at your pace and at your level of input so very attractive to most people.  For a 250 page book on commercial yabby farming go to www.rbmaqua.com.au

 

Markets – Yabbies are used for a mass of different purposes and this is great for commercial farmers as they have a market for every size, shape and colour yabby they can produce.  In NSW the demand for yabbies is phenomenal and all commercial farmers have more markets and far greater demand then they can possibly supply.  All the members of the NSWAA work together to help each other out and attempt to keep their customers supplied.

For further information on Commercial Yabby Farming power point presentation or go to www.rbmaqua.com.au

Sexing Yabbies

 

 

Determining the sex of your yabbies is easy.  You need to check the underside of the yabby.  Male yabbies have small projections on the inside base of the last walking pair of walking legs.  The female yabbies are smooth on the back legs without any projections but have 2 round openings on the inside base of the third pair of legs, they are hard to discern but these are the openings from which the females will lay her eggs under her tail.