In studies of blacklip abalone (Haliotis rubra) in Tasmania conducted during 1983 to 1987, Jeremy Prince and his research team made several important findings concerning the biology and fishery management of this species. These include:

• Rate of deposition of growth layers in the shell is closely related to age, and may be used to determine the relationship between age and size (Prince et al., 1988a). Sampling of populations may then be made to determine age structure and other demographic features.
• Experimental evidence was provided which suggests that larval dispersal is very limited, perhaps on the scale of tens of metres (Prince et al. 1987, 1988b).
• Catch rates are not closely related to abalone abundance except at high levels of exploitation (Prince 1992). Hence, monitoring of catch-effort statistics is not a useful means of detecting population changes (particularly declines).

When reviewing the findings of his work, Prince (1989: 145-6) concluded that an understanding of the population dynamics of H. rubra and of the sustainable levels of fishing might best be achieved by elucidating the relationship between spawning stock biomass and recruitment. It was as a result of this belief that the present study was proposed by Prince, and an application to the Fishing Industry Research and Development Council (FIRDC) for the funding of a stock-recruitment study was submitted shortly after I assumed the position of abalone biologist after Prince's departure.

When preparing the application, it was immediately apparent that the accuracy of measurement of the stock-recruitment relationship (SRR) depends on the accuracy with which abundance (or biomass) of both stock and recruits can be measured. The research proposal submitted to FIRDC therefore was intended to address the question of how accurately abalone abundance can be measured. (See below for the objectives of this study.)

The study was designed as a multi-State study: methods would be developed in Tasmania, and these methods would then be applied in other abalone-producing States (at least two of Victoria, South Australia and New South Wales). At each study site the accuracy with which abundance could be measured would be determined; these sites would then be used to measure the relationship between stock and recruitment.

The general experimental procedure was to manipulate abalone densities at each of three sites (final densities to be high, medium and low) within a region, then to monitor subsequent recruitment rates at these sites. This would be repeated at four regions around Tasmania, and at a single site in other States. This experimental design relies critically on the validity of the finding of Prince et al. (1988b) that larval dispersal is limited to a scale of metres or tens of metres; if this were not the case then the abundance (or density) of the parental population from which recruitment was derived would be impossible to determine.