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



477 



Age (years) 



Figure 5 



Von Bertalanffy growth curves for kelp bass (Paralabrax 

 clathratus) and barred sand bass (P. nebulifer) from south- 

 ern California. Dotted curves are the 95^ prediction lim- 

 its about the von Bertalanffy regression lines. 



just one set of parameters. A nonsignificant F-value 

 (F 3397 =0.60, P>0.05) indicated that no significant 

 additional variation was explained by assuming dif- 

 ferent values for the three von Bertalanffy param- 

 eters for each species. 



In their early years, both species grew fairly 

 quickly, a few reaching 20 cm TL in their first year 

 (Fig. 5). Growth rates declined at around age 5. The 

 von Bertalanffy parameters for all kelp bass (with 

 standard errors in parentheses) were/ ,=69.8 (3.76), 

 6=0.06 (0.008), t o =-3.50 (0.48); those for all barred 

 sand bass were I =66.2 (5.08), 6=0.08 (0.014), t =2.63 

 (0.63). The oldest kelp bass aged was 33 yr, and the 

 oldest barred sand bass was 24 yr; however, most 

 fish sampled were less than 15 yr old. 



Length and age at first maturity 



Both male and female kelp bass matured within a 

 relatively narrow length range and at about the same 

 age (Figs. 6 and 7). While a few males and females 

 matured at 18 cm, 50% of males matured at 22.0 cm 

 and 50% of females at 22.6 cm. All males were ma- 



ture by 26 cm, all females by 27 cm. Males matured 

 between the ages of 2 and 4 years; females between 

 2 and 5 years. 



The smallest mature male barred sand bass that 

 we found were 19 cm, the smallest females were 21 

 cm (Figs. 8 and 9; Table 2). All males were mature 

 by 26 cm, all females by 27 cm. Length at 50% matu- 

 rity was 21.9 cm for males and 23.9 cm for females. 

 As with kelp bass, male barred sand bass matured 

 between the ages of 2 and 4 years, and females be- 

 tween 2 and 5 years. 



Discussion 



Recruitment and annual abundance 



In the annual recruitment pattern, kelp bass is a late 

 spring to early fall spawner. Because this species has 

 a pelagic larval phase lasting at least one month ( But- 

 ler et al., 1982), most of this recruitment pattern 

 would be expected. The peak of recruitment seen in 

 December may represent an artifact of slower win- 



