TEGNER ET AL.: BIOLOGY AND MANAGEMENT OF RED ABALONES 



total mortality rate over most of the size and age 

 range, we believe that the method gives an estimate 

 of the total mortality rate which is not much greater 

 than the natural mortality rate. 



Initial values and bounds, and their rationales, are 

 shown in Table 1. We forced the estimation proce- 

 dure to produce estimates of growth rate param- 

 eters consistent with the tagging results from 

 Johnsons Lee (P. Haaker^). The lower bound on K 



was set at 0.269, resulting in an estimated X equal 

 to this; and the last mean length was constrained 

 so as to obtain an estimated L„ of 201 mm. Bounds 

 on the standard deviations of lengths-at-age around 

 their means were based on inspection of the length- 

 frequency data (Figs. 2, 3). 



'P. L. Haaker, California Department of Fish and Game, 330 

 Golden Shore, Long Beach, CA 90802, pers. commun. 1986. 



1978 

 N = 53 



 If J l 



95 125 

 SIZE (mm) 



Figure 2.— Size-frequency distributions of red abalones recovered in the destruct 

 quadrats by year, 1978-82. The data were scaled for differences in effort between 

 years as follows. Each 5 mm size category for each year was divided by the respec- 

 tive total number of animals found for that year and then multiplied by the densi- 

 ty for that year to yield a density at each 5 mm size category for that year. As 

 the resulting numbers are small, each entry was multiplied by 100. The dashed 

 lines indicate sport (178 mm) and commercial (197 mm) legal minimum sizes. 



317 



