yabby

Although the name Yabby is often used to describe any Australia freshwater crayfish, it most properly belongs to the Cheerax destructor.

Yabbies can live in virtually any body of fresh water, running or still. They burrow into muddy banks and sleep during drought, only to emerge when the rains come. 

Yabbies grow to be about 16cm long in total, with the carapace measuring approximately 7cm.
They are brown, blue, green, or almost red in colour, depending on where they live. Yabbies are found naturally in much of South Western Queensland, central and western New South Wales, the majority of Victoria and the eastern part of South Australia.

An enjoyable way to pass an afternoon is sitting on the edge of a dam with a piece of string with a small piece of meat tied to the end, waiting for a yabby to bite the meat and be caught. While most people take the yabbies home and cook them like little lobsters, I'm afraid we always took them home and put the in an unused aquarium with mud and dam water, and watched them for a week or so, them let them go again.

Yabbies (Cherax albidus or Cherax destructor) are a form of crustacean, more specifically a freshwater crayfish, originating in the eastern parts of Australia. They are often incorrectly called koonacs (Cherax plebejus or Cherax glaber), gilgies (Cherax quinquecarinatus or Cherax crassimanus) or marron (Cherax tenuimanus).

In the 1930s, a farmer from Narembeen, Western Australia, brought back a few yabbies from Victoria, and put them in one of his farm dams. The yabbies thrived on the muddy water and warm water temperature. Other farmers have since put yabbies in their own dams, more for the novelty of being able to catch their own seafood even though they live hundreds of kilometres from the coast, rather than for any practical purpose.

In the 1990s farmers began to realise the potential of yabbies, and started selling them. Nearly all of them were sold to distributors, who exported them all over the world, though mainly to Europe and Asia. Today, yabbies are being farmed and sold in increasing numbers.

In Western Australia (which easily accounts for more than half of Australian yabby production), yabbies are usually grown in farm dams. This is convenient, as farm dams are already there for the purpose of watering stock. Some farmers use specially built yabby ponds, which are usually 1.5-2 metres deep, and 40x25 metres in length and width. Yabbies prefer fresh water, and above salinities of one quarter that of seawater, they cease growing. Above half seawater, they start dying. Muddied waters are not a problem, and are often useful as predators (such as cormorants) cannot see them. The optimum water temperature for production is 28ºC, so in W.A. the growth of yabbies slows almost to a stop over winter.

Yabbies mostly eat organic material that is washed into the dams by rain. Better yields are achieved by feeding the yabbies. Suggested feeds are grains such as wheat, barley and lupins, as well as straw. The feed is simply thrown into the dam for the yabbies to eat off the bottom.

Yabbies are best caught in traps. Drag-netting pulls the yabbies through the mud at the bottom of the dam, which contains bacteria that will kill the yabbies if it gets in their gills. The most popular and effective trap used in W.A. is the Mulataga trap. Before the Mulataga trap, box traps were used. Diagram of Mulataga trap:

Side view:
              bait pipe
                 |   
                 V 
         ________o_________
        /                  \    <- shadecloth sides
       /                    \
      /______________________\
              ^
              |
           thin metal mesh floor

Front view:
        ________
       /        \
      /          \
     /____________\
    

The Mulataga trap consists of a frame made of steel rod (approx. 8mm diameter), with a bottom made from thin steel mesh, sides made from shadecloth (or any other type of waterproof, tight-knitted netting), and a top made from thin plastic. When not in use, the net folds flat, when about to be used, the top of the frame is lifted upwards, and held open by a piece of P.V.C. pipe, which is filled with bait. The best bait is generally considered to be any type of whole fish, such as sardines. The idea behind the nets is that the yabbies are attracted by the bait, they climb the sides of the net, and then fall in through the top.

The first step in catching the yabbies is to set and bait the traps and then put them into the dam. Traps must be far enough from the edge of the dam so that they sink to the bottom where it is around 1.5 metres deep. This is the depth that yabbies usually live, as the water temperature is suitable. Traps are generally placed approximately 5 metres away from each other, but this is dependent on the population of the dam. The traps are left for 24-48 hours before they are retrieved. If they are left for too long, the yabbies tend to start eating each other. Once the traps are pulled out, the yabbies are sorted by size immediately into two groups - sellable (above 30 grams) and unsellable. The unsellables are thrown back into the dam, while the sellables are gill-washed. This involves placing them in a bucket full of clean water, where any mud that was caught in their gills as the net was pulled out will be flushed from their systems. The yabbies are then packed into cooled eskies for transport. Yabbies can be trapped every month or more often, it is, of course, dependent on the yabby population and conditions.

Yabbies are a useful side-project for many farmers. Due to the small amount of yabbies available to consumers, prices are quite decent. The below table shows farm-gate prices (i.e. price received by the farmer for his sales) for yabbies:

  ______________________________
  | Weight (g) | Price (AU$/kg |
  |   < 30     |    not sold   |
  |   30-40    |    5.00       |
  |   40-50    |    7.00       |
  |   50-60    |    8.00       |
  |   60-70    |    9.00       |
  |   70-80    |    10.00      |
  |   70-100   |    12.00      |
  |   > 100    |    13.50      |

As for taste, yabbies lack the taste of saltwater crayfish. They are a little more bland. One presumes that they only sell so well in foreign countries because there are yuppies in every part of the world, and they love to sound intelligent and cultured by ordering something off the menu that their fashionable friends haven't heard of before.