aquaculture

The Australian Rural Industries Research and Development Corporation has published The New Rural Industries – A handbook for Farmers and Investors. Of interest to prospective yabbie farmers and aquaculturalists in general is the chapter on yabbie farming. The web page does not include some of the graphics but the full document is available as a .pdf. From the introduction:

Yabbies (Cherax albidus and Cherax destructor) are indigenous to central and eastern Australia and have received considerable aquacultural interest. Although some yabbies are produced from ponds on purpose-built farms, the vast majority of commercial yabbie production in Australia comes from trapping in farmers’ dams what are essentially wild yabbies. This use of existing farm dams originally built to water stock has enabled rapid expansion of the industry because of the low entry cost. The yabbie industry currently harvests around 4000 farm dams in Western Australia. The rapid growth experienced by the industry is expected to continue, with processors reporting an increase this year of up to 400% in the number of farmers harvesting yabbies.

Australian yabbies are in demand internationally due to their high quality, larger size than crayfish produced by overseas competitors, acceptance by European markets as a replacement for diminishing stocks of their own native crayfish, freedom from major diseases and ability to be landed live in the major international markets.

Research has been undertaken to develop better performing varieties – often unmanaged populations become stunted because of overpopulation. Quantum – ABC Television reported in 1999 about the development of cross-breeding yabbies to produce all male offspring.

Dr Ian W Purvis of the Australian Government’s Rural Industries Research and Development Corporation has published Breeding Bigger Yabbies – Developing a genetically improved yabby to facilitate farm enterprise diversification. From the summary:

Aims of the Research
The objective of the research was to establish the best wild strains for aquaculture by discovering the heritability of desired characteristics, such as fast growth and large meaty tails. These strains were then selectively bred to develop a strain of yabby better suited to aquaculture.

Once such a yabby exists in an aquaculture environment, the yabby farmer can better control growth and quality of the livestock, important factors to maintaining a reliable and continuing market for this product.

Methods Used
Superior performing broodstock yabbies, from various geographic populations, identified by a strain comparison trial were combined to create a new “commercial” strain and subjected to four generations of within family selection. Faster growth was the primary selection goal. At the beginning of the trial the program was based on the evaluation of 100 full siblings from each of 30 families. Poor survival of three families reduced the total number in the program to 27. A control line consisting of randomly bred individuals from the 30 families was also maintained to allow assessments of genetic gain to be made through selective breeding.

Results
Of the four generations of selection, significant differences in mean liveweight at harvest were observed between select and control lines. The difference represented an average response to selection in both sexes of 12% per generation and a realized heritability for liveweight of 30%.

These results demonstrate that response to selection for liveweight in the yabby, Cherax destructor, can be successfully achieved. By selecting within families, significant gains were achieved in generations F2 and F3 that averaged around 15%. Coupled with the initial gains achieved by selecting the F1 founder generation, the select animals in generation F3 grew at 60-70 % faster than the average of all strains taken from the wild to initiate this study.

The full report is available as a .pdf.