The yabby industry in consultation with researchers from the Fisheries Department of WA have identified the following areas of research required to sustain the continued growth of this relatively new form of aquaculture
1. FEEDING AND NUTRITION
The previous FRDC project demonstrated that there was considerable scope for improvement in feeding practises by farmers. Increased feed rates and the inclusion of animal based protein sources in diets result in faster yabbie growth. Industry now requires the evaluation of alternative feeds using on-farm sources of low cost feeds. In addition to types of feed, the optimum feeding rates need to be determined.
Due to the large distances between farm dams, industry also requires the evaluation of alternative feeding practises such as automatic feeders.
A number of new diets are either being produced or currently being formulated by small business, farmers and universities. Industry requires trials to determine the effectiveness and economic viability of these new diets.
Feeding experiments for yabbies cannot be achieved in farm dams due to the variability of production between dams and lack of ability to measure stocks precisely. These experiments need to be run at the Avondale Farm Dam Aquaculture Research Station, where controlled conditions prevail, providing sound replication, with established controls, repeatability and known variation between ponds.
2. OXYGENATION
Increased feeding rates result in decreased dissolved oxygen levels on the bottom of dams where yabbies live. In addition, the centre of most dams acts as a nutrient sink resulting in anaerobic conditions avoided by yabbies. Previous experiments have demonstrated that growth is highly density dependant. Therefore, the rejuvenation of these anaerobic areas will effectively lower density (yabbies/m2) by providing more area to inhabit and thus increase growth. The connection of power to widely dispersed and isolated farm dams for mechanical aeration is not economically feasible.
In preliminary experiments at the Avondale Farm Dam Aquaculture Research Station it was shown that dissolved oxygen levels can be increased using a cheap chemical additive, while at the same time converting anaerobic sediments to aerobic sediments. The optimal application rate of this chemical for increased yabbie production needs to be quantified.
3. HUSBANDRY
Industry is investigating the potential for winter production, using shallow purpose built ponds. In order to assess whether these ponds are feasible an economic evaluation is required.
To increase farm dam production, farmers require methods of identifying the most productive regions of the south west and indices of which dams are the most productive. This continues our previous extension work investigating factors limiting production and the variation in yields between farm dams.
The previous FRDC project demonstrated that trap harvesting may be having a negative selection impact upon the yabby gene pool. Trapping selectively removes faster growing animals and males, while leaving slower growing animals and females to breed. The application of alternative harvesting methods needs to be evaluated.
4. POLYCULTURE
Predator polyculture was proposed by researchers in WA over three years ago and farmers are currently stocking either silver perch or black bream into yabby dams, to harvest both fish and yabbies. To determine the viability of this approach, industry requires an economic evaluation of polyculture. This needs research data on survival rate, growth rate, feed cost and yield of both fish and yabbies.
