Love et al Life history aspects of Paralabrax clathratus and P. nebulifer 



475 



pothesis that there was no difference between the 

 growth rates of kelp bass and barred sand bass by 

 constructing a "complete" least-squares, nonlinear 

 regression model that fitted the three von Bertalanffy 

 parameters t , l m and k separately for each species. 

 We then used an F-test to compare the amount of 

 variance explained by this separate species model 

 with that explained by a "combined-species model," 

 fitting the data for both species to just one set of pa- 

 rameters. A nonsignificant F- value indicated that no 

 significant additional variation was explained by 

 assuming different values for the three von Berta- 

 lanffy parameters for each species. 



Length and age at first maturity 



We sampled kelp and sand bass in July-August 1988- 

 89, July 1991, and June-August 1992. As we have 

 noted previously in rockfishes (Sebastes spp., Love 

 etal., 1990), white croaker (Genyonemus lineatus, Love 

 et al., 1985), and California halibut (Paralichthys 

 californicus, Love and Brooks, 1990), it is often diffi- 

 cult to distinguish immature from mature fishes 

 during their nonreproductive seasons. Thus, we con- 

 centrated our sampling on the summer months, well 

 within the spawning seasons of the two species. Most 

 of the sand bass were taken by a 7.6-m semiballoon 

 trawl, by hook and line, or by gill nets between Ma- 

 rina del Rey and San Diego. Kelp bass were taken 

 by hook and line and gill nets between Redondo 

 Beach and Newport Beach and at Santa Catalina and 

 San Clemente islands. Fish were frozen until ana- 

 lyzed, when they were measured (TL) and both sag- 

 ittal otoliths and gonads were removed. Gonads were 

 examined without magnification to determine sex and 

 gonad state. Annuli from otolith sections were counted 

 under water with a dissection microscope. Sixty-eight 

 male ( 16-36 cm TL) and 84 female ( 14-35 cm TL) kelp 

 bass as well as 66 male ( 12-33 cm TL) and 85 female 

 ( 13-35 cm TL) barred sand bass were examined. 



The relationships between length and maturity 

 and age and maturity were established by using a 

 natural log transformation of the equation 



In 



(1-1) 



P x = 



1 



l + e ax+b 



(Gunderson et al., 1980) to yield 



In 



(1-1) 



ax + b, 



where p x is the proportion mature at length or age x, 

 and a and b are fitted parameters. We then plotted x 

 against 



using simple linear regression (SAS, 1988) to esti- 

 mate values for a and b. Fifty-percent maturity was 

 calculated by using fitted values of a and b, and by 

 using/? = 0.50 to solve for x. 



Results 



Recruitment and annual abundance 



Kelp bass showed considerable seasonal variation in 

 recruitment at the King Harbor breakwater (Fig. 3). 

 A few newly settled recruits were found in April, more 

 in May, but most were observed during transects con- 

 ducted in the fall and winter. Surveys of young of 

 the year ( YOY), subadult, and adult kelp bass in King 

 Harbor showed a distinct temporal pattern (Fig. 4). Low 

 in the mid-1970s, YOY abundance increased sharply 

 from 1977 to 1979, decreased in the early 1980s, and 



Kelp bass 



n = 1 ,396 recruits 

 432 transects 



J±l 



I 



Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

 Month 



Figure 3 



Monthly recruitment of kelp bass, Paralabrax clathratus, 

 ( 1986-92 1 at the King Harbor ( Redondo Beach, California I 

 breakwater. We considered recruitment to any month to 

 have occurred between the 16th day of the current month 

 and the 15th of the next month. Means are based on 

 monthly data from 1986 to 1990. Error bars represent ± 

 one standard error. 



