474 



Fishery Bulletin 94(3), 1996 



covered by additional resin. After curing, the hard- 

 ened resin bar was taken from the mold. 



We used a Buehler Isomet saw with two low-den- 

 sity diamond blades separated by a thin (0.3-0.5 mm I 

 metal shim to section each otolith. Otolith sections 

 were placed in a 50% solution (by volume) of glycerol 

 in water and cleaned in an ultrasonic bath for 2-3 

 minutes. After cleaning, sections were dried and 

 stored in labelled plastic bags. Sections were later 

 placed on a glass slide, cleaned with 2-3 drops of 

 toluene, and mounted with enough cytoseal to cover 

 the structures and ensure permanent storage. 



Many fishes lay down annually an opaque and a 

 hyaline (translucent) zone in their otoliths. Seasonal 

 variations in calcium deposition may be responsible 

 for this zonation (Irie, 1960). By calculating the per- 

 centage offish with otoliths with opaque margins in 

 our monthly samples, we attempted to validate that 

 the bands were formed annually. It seems reason- 

 able to assume that band deposition was seasonal if 

 the bands were present during one part of the year. 

 Kelp and sand bass do appear to lay down seasonal 

 bands, beginning in spring and continuing into fall 

 (Fig. 2). In both species, the first three annuli were 

 usually readable. The fourth one was often more dif- 

 ficult to distinguish; however, bands subsequent to 

 number four were clear. 



Lengths at ages were estimated by direct observa- 

 tion of otolith annuli from 261 kelp bass and 137 

 barred sand bass. Growth was assumed to be de- 

 scribed by the von Bertalanffy growth curve model 

 (von Bertalanffy, 1938): 



100  



B0 

 70 

 60 



'•0 

 40 



30 



20 



10 







Kelp bass 



1 IC 

 • 



80 



70 - 

 BO 

 50 



40 - 

 30 

 00 

 10 

 



11111111 I I — 

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



Barred sand bass 



.On 



"1 1 ' ' I ' ' I ' ' I — " 



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



Month 



Figure 2 



Seasonal deposition of opaque edges in kelp bass 

 (Paralabrax clathratus I and barred sand bass (P. nebulifer) 

 otoliths from southern California ikelp bass, n =204; barred 

 sand bass, n=238). 



l l= l„(l- e - k " ). 



where l t = length at time t; 



l a = theoretical maximum length; 



k = constant expressing the rate of approach 



to I j, and 

 t = theoretical age at which l t - 0. 



Growth equation constants for the von Bertalanffy 

 growth model were calculated from length-at-age 

 data for each species by using the Marquardt method 

 of iteration in a least-squares, nonlinear regression 

 (SAS, 1988). We were unable to accurately fit these 

 functions separately by sex for either species because 

 of our relatively small sample sizes and, in particu- 

 lar, because of the absence of smaller-size fish that 

 could be unambiguously sexed. We did test the hy- 



