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



06 



0-5 ^ 04 



UJ 02- 



1978-1982 

 N = 455 



65 95 125 155 

 SIZE (mm) 



Figure 3.— Size-frequency distribution of red abalones found in the 

 destruct quadrats summed for 1978-82. The scaled data from Figure 

 2 were summed across each 5 mm size category (A). Proportion of the 

 total number of abalones found in the destruct quadrats which were 

 emergent, visible to a diver without turning rocks or the use of a light, 

 as a function of size class. These data were also scaled for differences 

 in effort between years (B). The dashed lines indicate sport (178 mm) 

 and commercial (197 mm) legal minimum sizes. 



Yield-Per-Recruit Analysis 



A program was written to calculate yield-per- 

 recruit from equation 10.20 of Ricker (1975). 

 Asymptotic weight W^ was set to 1,500 g, based 

 on length-weight data collected from Johnsons Lee 

 in 1974 (CDFG, unpubl. data), and an L„ of 201 

 mm. Maximum age A was arbitrarily set to 25. K 

 was set to 0.269, based on the tagging results 

 (Haaker fn. 3). Two values of natural mortality rate 

 M were used: 0.10 and 0.15, based on the results 

 of this study. 



To obtain isopleth diagrams, the instantaneous 

 fishing mortality rate F was varied systematically 

 from 0.0 to 2.0. The minimum size at first capture 

 was varied from 140 to 200 mm. 



Yield estimates were also made for pink abalones. 

 Doi et al. (1977) reported growth parameters for 

 males and females from two sites. We used the 

 values for females from Cedros: L„ = 186.0 mm, 

 K = 0.233, and t^ = 0.096. These authors estimate 

 that M = 0.35 at that site. We used this value and 

 also M = 0.20 based on the estimated survival curve 



from Tutschulte (1976, p. 250). W^ was set at 

 1,216 g, based on the biometric data of Doi et al. 

 (1977). Minimum size was varied from 100 to 180 

 mm, and F from 0.0 to 2.0. 



Fecundity 



Egg-per-recruit analysis requires knowledge or an 

 estimate of the way that average fecundity varies 

 with length. Because the procedure compares egg 

 production under specified conditions with egg pro- 

 duction in the unfished condition, the absolute num- 

 ber of eggs is not required; only the form of the rela- 

 tion is important. 



Four sets of red abalone fecundity data were ex- 

 amined. These were Giorgi and DeMartini (1977), 

 two sets from Ault (1982, 1985), and a set furnished 

 by E. E. Ebert". The first set of data in Ault (1982, 

 1985) was from a field collection; the second was 

 from laboratory-conditioned animals. 



■"E. E. Ebert, Marine Culture Laboratory. California Department 

 of Fish and Game. Monterey, CA 93940, pers. commun. 1986. 



318 



