Catch statistics for 13 species from commercial and research trawls conducted between 1979 and 1984 in the southern areas of the South-East Trawl fishery are examined. Catch and catch per swept area from demersal trawls were stratified by position, depth and month and shots were subsequently amalgamated into statistically different groupings. It is suggested that these groups be targeted by fisheries managers for particular attention when conducting biological studies of the fish stocks. A novel management regime based on deliberate over exploitation of selected discrete stocks is proposed and it is argued that only a combination of biological studies and experimental manipulation can lead to a reliable management strategy. It is suggested that catch per unit effort of trawl could never be refined to the extent required by any reasonable population model and that CPUE is valid only for models of that part of the fishery that exists above sea level, such as the economic component. This report was prepared for the Tasmanian Department of Sea Fisheries FIRTA Grant 86/45.

The scientific literature has generally accepted that abalone populations are characterised by low levels of settlement and recruitment (Tegner in press), that mortality is relatively low (Doi et al. 1977; Beinssen and Powell 1979; Sainsbury 1982; Shepherd et al. 1982; Fournier and Breen 1983) and uniform throughout life (Shepherd et al. 1982), and correspondingly that the natural productivity of these stocks is low (Tegner in press). In some studies it has been noted that one or more year classes are apparently missing (Forster et al. 1982; Sainsbury 1982) and this has led to the conclusion that abalone recruitment is relatively sporadic and irregular. It has been generally assumed that larval dispersal is relatively widespread (20-50km; Tegner & Butler 1985). No relationship had been observed between the abundance of breeding stock and the abundance of recruitment. On the basis of these observations and laboratory studies, together with genera lly held assumptions, it has been accepted that oceanographic and other environmental factors would be the major determinants of settlement and recruitment density (Fedorenko & Spout 1982; Tegner in press).

It was these widely held views which led to the original rationale for this project, which was to develop an index of settlement or recruitment abundance which could be used to predict broad scale trends in the future abundance of the fishable stock.

In addition, there was also no scientifically proven method of ageing abalone prior to this study, and it was generally accepted that the Australian species of abalone could not be aged. The FIRTA-funded review of Ward (1986) found that this was a major impediment of research into and assessment of abalone stocks in Australia.

This report concludes investigations into the economic and biological viability of scallop culture in Tasmania. Research into spat settlement and ongrowing methods has continued from the 1970's and the current TFDA and FIRTA funded programmes (1980-84) have successfully cultured scallops to legal, marketable size. The purpose of this report is to examine the economic feasibility of a scallop farming venture based upon traditional methods of culture.