Abstract.- Catch and effort data 

 for the abalone Haliotis rub7-a fish- 

 ery off Victoria, Austraha, revealed 

 that catches were alHed to incentive 

 (price); annual catch was proportion- 

 al to effort. The robustness of the 

 fishery can be attributed to low fish- 

 ing mortality (F around 0.1) and a 

 relatively high minimum length of 

 capture (120 mm). Exploitation 

 models showed that egg production 

 was at least 50% that of unfished 

 stocks. The analyses also showed 

 that egg production was sensitive to 

 variation in the growth parameters; 

 fast-growing populations were more 

 vulnerable to recruitment overfish- 

 ing than slow-growing populations. 

 For slow-growing populations, yields 

 could be considerably increased 

 without endangering recruitment. It 

 is suggested, from the available 

 evidence, that overfishing has been 

 overemphasized in the collapse of 

 abalone fisheries. 



Exploitation modeis and catch 

 statistics of thie Victorian fisliery 

 for abalone Haliotis rubra 



Paul E. McShane 



Marine Science Laboratories, Fisheries Division, Ministry for Conservation and Environment 

 P.O. Box 1 14, Queenscliff, Victoria 3225, Australia 



Present address: Fisheries Research Division, Ministry of Agriculture and Fisheries 

 P.O, Box 297, Wellington, New Zealand 



Manuscript accepted 18 December 1991. 

 Fishery Bulletin, U.S. 90:139-146 (1992). 



Recent and comprehensive descrip- 

 tions of the state of the world's aba- 

 lone {Haliotis spp.) fisheries include 

 reviews of the abalone fisheries in 

 California (Tegner 1989, Tegner et 

 al. 1989 and 1992), British Columbia 

 (Breen 1986, Sloan and Breen 1988), 

 Australia (Prince and Shepherd 1992), 

 Mexico (Guzman del Proo 1992) and 

 Japan (Mottet 1978). A unifying 

 theme of these reviews is that aba- 

 lone fisheries are characterised by 

 initial high productivity followed by 

 irreversible decline. Australia has 

 developed an abalone fishery only 

 recently by world standards. In Vic- 

 toria, the fishery for the abalone 

 Haliotis rubra is productive, valu- 

 able, and apparently stable (McShane 

 1990). The government limits the 

 number of operators in the fishery 

 (71), the annual catch (1460 metric 

 tons) since 1988, and minimum 

 length of capture (120 mm). 



A fundamental objective of fish- 

 eries science is to predict the produc- 

 tion from a fishery under varying 

 management strategies. A common 

 approach is to consider the yield from 

 an individual or year-class of in- 

 dividuals under different fishing con- 

 ditions (Beverton and Holt 1957, 

 Ricker 1975, Gulland 1988, Megrey 

 and Wespestad 1988). Such exploita- 

 tion models treat populations as the 

 sum total of their individual mem- 

 bers; yield is expressed as yield-per- 

 recruit because the absolute level of 

 recruitment is rarely known. Yield- 

 per-recruit models have been applied 

 to several abalone fisheries including 



those for H. discus discus (Ishibashi 

 and Kojima 1979), H. iris (Sainsbury 

 1982a), H. laevigata (Sluczanowski 

 1984), H. kamtschatkana (Breen 

 1986, Sloan and Breen 1988), H. rufe- 

 scens and H. corrugata (Tegner et al. 

 1989), and the Tasmanian fishery for 

 H. rubra (Nash 1992). 



Although yield-per-recruit models 

 can provide information on appropri- 

 ate harvest strategies to maximize 

 yield, the results provide no indica- 

 tion of the sustainability of a par- 

 ticular harvest regime. Because of 

 the historical tendency of abalone 

 fisheries to collapse, increasing atten- 

 tion has been focused on manage- 

 ment strategies which maintain egg 

 production as well as yield (Sluc- 

 zanowski 1984 and 1986, Breen 1986, 

 Sloan and Breen 1988, Tegner et al. 

 1989, Nash 1992). 



In the present paper, the produc- 

 tivity of the fishery for abalone Ha- 

 liotis rubra off Victoria, Australia, is 

 described. To investigate the effect 

 of growth rate, the relative yields of 

 weight and eggs for two hypothetical 

 populations of H. rubra, fast- and 

 slow-growing, are examined. Man- 

 agement implications of my results 

 are discussed for H. rubra as well as 

 for other abalone species generally. 



Materials and methods 



Fishery statistics 



Data on annual catch, effort, and 

 price (whole weight) for the Victorian 

 abalone fishery were obtained from 



139 



