476 



Fishery Bulletin 94(3), 1996 



Adults and subadults 

 Young ol year 



74 75 76 77 78 79 80 81 82 83 84 85 86 87 



74 75 76 77 78 79 80 81 82 83 84 85 86 87 



Year 



Figure 4 



Mean abundance per transect of adults or subadults, or 

 both, and young-of-the-year (YOY) kelp bass (Paralabrax 

 clathratus) and barred sand bass (P. nebulifer) along the 

 King Harbor (Redondo Beach, California) breakwater 

 1974-90. Error bars are ± one standard error. Each point 

 represents mean of 96 five-minute diver surveys (8 sta- 

 tions and 3 depths surveyed quarterly). 



remained low for the rest of the decade. The abundance 

 of adults and subadults peaked from 1980 to 1983, prob- 

 ably reflecting the successful year classes of the previ- 

 ous few years, then declined somewhat in the mid- 

 1980's. The abundances of barred sand bass at all life 

 stages increased in the late 1970s (Fig. 4). Although 

 the numbers of YOY declined soon after, the popula- 

 tion of older fishes increased continuously, reaching a 

 peak in 1985. 



Age and growth 



For each species, we combined age-at-length data for 

 both sexes. We did this because we were unable to 

 accurately fit the von Bertalanffy growth functions 

 separately by sex because of our relatively small 

 sample sizes and, in particular, because of the ab- 

 sence of smaller-size fish that could be unambigu- 



ously sexed. We do not feel that by combining this 

 data undue bias was introduced into our results be- 

 cause the numbers of males and females comprising 

 the combined samples were approximately equal (kelp 

 bass, males = 86, females = 100; sand bass, males = 36, 

 females = 55) and because the separate fits for each 

 sex failed to show a significant difference in growth 

 rates for either species (kelp bass, t =0.059, df=182, 

 P>0.05; barred sand bass, r=0.004, df=87, P>0.05). 



We tested the hypothesis that there was no differ- 

 ence between the growth rates of kelp bass and 

 barred sand bass by constructing a "complete" least- 

 squares, nonlinear regression model that fit 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 



