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



from 1978 through 1982 are illustrated in Figure 

 2. The size-frequency distributions are signifi- 

 cantly different (G test, P < 0.001). By inspec- 

 tion, it is apparent that 1978 and 1979 are 

 dominated by smaller animals. The best year for 

 settlement (defined as young-of-the-year or <31 

 mm) was 1978 (Table 3), when the settlement 

 rate was about three times the average of the 

 other four years. These animals form a prominent 

 mode in 1979 but the mode is not distinguishable 

 in 1980. 



the method of Pennington (1983). Assuming no 

 changes in density between years, all data were com- 

 bined with appropriate weighting for sample size dif- 

 ferences to generate average densities of 0.179 

 m^^ (SE < 0.066) for the total number of aba- 

 lones, 0.027 m-^ (SE < 0.013) for sport minimum 

 legal sized, and 0.005 m-^ (SE < 0.0035) for com- 

 mercial minimum legal-sized animals. Due to un- 

 estimable correlation between annual data, standard 

 errors are given in terms of an upper bound. Despite 

 intensification of the red sea urchin fishery during 



Table 3.— Results from the destructively sampled quadrats, 1978-82. 



The densities of different size categories of red 

 abalones and of red and purple sea urchins in the 

 destruct quadrats for 1978 through 1982 are pre- 

 sented in Table 3. There were no significant changes 

 in the densities of the total number of abalones, 

 young-of-the-year, sport legal minimum (>178 mm), 

 or commercial legal minimum (>197 mm) sized 

 animals based on 95% confidence intervals around 

 the mean densities. Unequal sample sizes between 

 years and the large number of quadrats with no 

 abalones precluded analysis by ANOVA or the 

 Kruskal-Wallis test. By separating those quadrats 

 that contained abalones from those in which no 

 animals were found, a conditional distribution for 

 the nonzero valued samples could be proposed and 

 tested. Several tests of normality did not reject the 

 hypothesis that the natural log of the nonzero values 

 is normally distributed. Annual total average den- 

 sities and their variances were then estimated by 



this period (Kato and Schroeter 1985), there was no 

 change in red sea urchin density (Kruskal-Wallis 

 test, 0.05 < P < 0.01). In contrast, there was a sig- 

 nificant increase in purple urchin density (Kurskal- 

 Wallis test, P < 0.001). 



Abalones occupy different microhabitats as their 

 length increases (Cox 1962; Shepherd 1973, Tegner 

 and Butler 1989), and microhabitat selection affects 

 vulnerability to fishing (Witherspoon 1975). The 

 proportion of emergent abalones from the destruct 

 quadrats (1978-82 pooled, n = 455) is plotted in 

 Figure 3 as a function of size class. There is an in- 

 crease in percent emergent with increasing size 

 which appears to level off at about 150 mm and 70% 

 emergent and then decline as the animals attain 

 legal size and emergent animals are apparently 

 fished. Thus a substantial proportion of the largest 

 animals in the population remain cryptic. Neverthe- 

 less, the low proportion of the population constituted 



322 



