FISHERY BULLETIN: VOL. 87, NO. 2, 1989 



FISHING MORTALITY RATE 



Figure 9.— Relative values of various combinations of minimum size limit and fishing mortality rate, 

 using the procedure described in the text and the parameters of Figure 7. Values have a range of 



able stocks because animals this size would have a 

 high probability of attaining legal size. 



One of the goals of the limited entry legislation, 

 which went into effect in 1977, was to reduce the 

 turnover rate of fishermen; presumably fewer divers 

 with more experience would reduce the frequency 

 with which sublegal abalones are picked and re- 

 placed. Similarly, the reduction in the sport daily 

 bag limit in 1976 was accompanied by a requirement 

 that the first four legal-sized abalones taken must 

 be kept; exchange for larger abalones was forbid- 

 den (Cicin-Sain et al. 1977). The shell size-frequency 

 data (Fig. 5) clearly indicate that bar cut mortality 

 is continuing in the 1980s. The low density of com- 

 mercial-legal minimum-sized abalones (Table 3) sug- 

 gests that bar cuts also reflect intense pressure on 

 a scarce resource; many animals must be picked and 



measured to sort out the few legal-sized individuals 

 (Burge et al. 1975). 



Sea stars are the most abundant of the potential 

 abalone predators at Johnsons Lee, but their role 

 is not clear. A large study of sea star foraging at 

 the Hopkins Marine Life Refuge in central Califor- 

 nia reported no observations of abalone being eaten 

 by sea stars (Harrold 1981 reported in Hines and 

 Pearse 1982) but Pycnopodia is known to have very 

 different diets in different habitats (Mauzy et al. 

 1968). Montgomery (1967) demonstrated that young 

 (<100 mm) red abalones exhibit strong flight 

 responses to Pycnopodia in aquaria experiments. 

 Similarly, Hines and Pearse (1982) observed that 

 contact with Pycnopodia caused abalones to rapid- 

 ly move 5-20 cm deeper into crevices at Hopkins. 

 This behavior, plus the large number of juvenile 



332 



