Bacterial infections (currently Vibrio harveyi) are emerging as mortality episodes related to stress events which are out of abalone farmers’ control. Data for appropriate antibiotic use is unavailable. Inappropriate unregulated use in shellfish including abalone has led to antibiotic resistance and residue problems in several countries. Legal antibiotic access is limited, will worsen with proposed legislative changes, and in the longer term would require at least MUP registration.

MUP would require data on a range of parameters, including tissue levels achieved with various dose rates and how this varies with size, species, temperature and physiological state, duration of residues in tissues, acute and longer term toxicity, and efficacy against the pathogens of concern under the proposed conditions. Environmental safety data requirements would limit the choice of antibiotics to those already available for other aquatic animals, that is oxytetracycline, amoxycillin, potentiated sulphonamides (trimethoprim / sulphadiazine combination), and possibly quinolones such as oxolinic acid. Each of these has major potential limitations in either stability or bioavailability under marine conditions, efficacy against current pathogens, or acceptability for aquaculture use (quinolones). Volumes required for bath treatments, leaching from feeds, and cessation of feeding in infected abalone may all limit practicality.

To address all these parameters for MUP application in not warranted unless sufficient stability, bioavailability, and tissue levels are achieved, hence this preliminary study of the practicality of administration and in vitro and in vivo bioassay of bioactivity. The techniques developed for in vitro assessment of abalone antibacterial defenses and the in vivo infection model will also indicate the role of stress and whether alternate approaches to disease control also warrant investigation. Industry appreciates avoidance is preferable to treatment, and though stress may be unavoidable, understanding its role and being able to measure the effect may assist in developing alternate strategies.

A major problem facing abalone farmers in temperate Australia is the high operating costs associated with holding animals for 4 years until they reach market size. In other shellfish, selective breeding has substantially improved a number of traits (particularly growth rates & disease resistance), however no such program exists for abalone. An appropriately designed selective breeding program could produce abalone with growth rates enhanced by up to 30% over 3 generations of selection (6--8 years). This could shorten the production cycle by over a year, and thus substantially reduce farm operating costs.

With the continuing enthusiasm for abalone aquaculture both on-shore and off-shore across southern Australia, as well as developing in northern Australia, significant growth of the industry can be expected. Within the next decade it is possible that abalone aquaculture production will exceed the wild fishery in value.

(For FRAB Information repeated from Background)
How the Priority was determined –

The FRDC Board will remember that last year large, high cost approach was submitted that attempted to integrate all aspects of genetic development across all states. The FRDC Board rightly indicated that this was an expensive approach and concern was expressed at the time that all parties had not been properly integrated into the application. The FRDC Abalone Aquaculture Subprogram Steering Committee re-determined the critical R&D priorities with regards to development of a genetic improvement program for the abalone farming industry. The output was a defined plan that had 3 critical areas that needed to be developed. These were:

1) Development of a practical selective breeding protocol
2) Development of a R&D Genetic Business Plan
3) Commence the establishment of on-farm family lines and data collection

An expression of interest was called by the Steering Committee that addressed these three key research areas, for a set budget (approximately $130k), was national in its approach and for no more that 18 months. The application was seen as part of an ongoing research program that was to be established in abalone genetic breeding, with these three areas needing to be addressed before the next stage could commence. It also took advantage of the capacity of the industry to manage on farm selection both technically and physically.