In May 2006 an epidemic caused by Abalone Viral Ganglioneuritis (AVG) began infecting wild stocks of abalone in the Victorian western zone, rapidly spreading through the zone causing mortality rates of 40-95%. In response infected reefs have been closed since infection and to date remain closed resulting in the zonal TAC being reduced by >90%. It is the observation of WADA’s divers that, having been closed to fishing for several years, the reefs that suffered relatively lower mortality rates (75%) are, to this time, recovering well. Supported by an FRDC TRF project ‘Indicators and strategies for resumption of harvesting following catastrophic loss of abalone’ WADA members agreed that these ‘lightly’ impacted reefs should be closed for at least threes closure before being re-opened (some in 2009) with conservative size limits and catches.

In contrast to reefs that suffered relatively low mortality rates WADA’s divers observe that a number of formerly important reefs which suffered high mortality rates (>90%) do not appear to be recovering. Worryingly Californian studies suggest disease related reductions of abalone grazing pressure can lead to overgrowth of suitable settlement surfaces which retards natural rates of re-colonisation. WADA estimates one ‘high mortality’ reef, Kilarney, lost 100-200t of biomass and members are concerned that without intervention there will be a semi-permanent loss of productivity from some important reefs.

To prevent this WADA’s members are discussing initiating in 2009 rehabilitation projects for heavily impacted reefs by alternatively:
• Re-seeding of hatchery produced juveniles,
• Translocation of adults from other reefs in the western zone
• Long term closure to allow natural recruitment processes.

A cost-benefit analysis of alternative rehabilitation techniques is needed to inform members of the relative merits of alternative rehabilitation techniques and the likely magnitude of cost for rehabilitating at the scale of entire reefs.