Most jurisdictions have developed and used various combinations of indicators in stock assessment and TAC setting of their abalone fishery. Applications often use a time series of commercial catch rate or FIS density to detect trends and identify reference points of stock status. The use of fishery dependent indicators from logbooks and GPS loggers have been criticized for their potential to be biased and insensitive (‘hyper-stable’) because of commercial selection of all observations that are made. As a consequence, Fishery Independent Surveys (FIS) have also been used in stock assessment, with varying coverage in all state’s abalone fisheries. However, FIS have also been criticized for their large cost and considerable uncertainty about how representative and useful the data is for intensely spatially-structured abalone fisheries (e.g. spatial mismatch of the FIS and the stock). FIS reviews in several states found variable relationships between FIS estimates and other indicators of the fishery.

Alternatively, both GPS loggers and FIS have considerable complementary strengths. GPS logger information has strengths of extensive fine-scale detail about catch (e.g. allowing spatial standardisation, that represents one of the main challenges to fishery dependent data) with good coverage of the fishery, while FIS have strengths of repeatable and local scale detail that is independent of the fishery.

The project will review data available from GPS loggers, catch records and FIS in WZ Victoria, with possible extension to other fisheries depending on data access and funding. Methods to calculate density and biomass from different sources of data will be consolidated and applied at different spatial scales, and the precision and statistical coherence of estimates compared. These comparisons will enable the development of criteria to improve design of FIS, logger programs and related observations, and recommendations and guidance on the use of indicators of legal density and biomass in fishery harvest strategies.

Local abalone populations can be severely depleted by a range of impacts, including loss of habitat from the spread of sea urchins, diseases such as AVG and Perkinsus, environmental change and theft. Many of these impacts have been increasing for over a decade, although impacts of sea urchins on abalone and reef habitats in the last 5 years have been spreading in eastern Victoria, and appear related to climate change. Similarly, impacts remain from the spread of AVG through western Victoria.

There is evidence that production from commercial abalone fisheries continues to be reduced by the ongoing increase in external impacts to local abalone populations. While tools have been developed at a small-scale to help recover abalone populations, there is a strong need to investigate, implement and assess these at a larger scale to be able to minimise further impacts and recover productivity of abalone populations.

VicFRAB this year rated its highest priority to facilitate the investigation of translocating abalone to address declines caused by urchins and disease. Similarly, the NSW DPI strategic research plan identifies a priority to "determine methods to restore depleted reefs of abalone through techniques such as transplants, habitat rehabilitation and reseeding". The ACA Strategic Plan also details actions to plan and support remedial action to reduce the impact of pests, disease and theft on abalone.

The ongoing spread of impacts to local abalone populations is having a broad impact on shallow reef habitats. Small-scale research has demonstrated the potential of recovery techniques, but have not been implemented at a broad scale to actually attempt to recover lost productivity. This project will address the need to investigate the scaling up of recovery techniques, and their costs and long-term benefits, in an attempt to recovery lost productivity from abalone populations in south east Australia.

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.