LOVE ET AL.: LIFE HISTORY AND FISHERY OF WHITE CROAKER 



Table 3. — The 1 most abundant fish species taken by otter trawls 

 in three depth intervals off Southern California, 1972-80. 



where L, 

 k 



sanddab dominated in waters between 59 and 109 m, 

 declining in numbers both inshore and offshore. 

 California tonguefish exhibited an abundance pat- 

 tern like white croaker, with numbers peaking in 

 inshore waters and declining with greater depth. 



Most juvenile white croaker (50% mature by 15 cm) 

 were limited to the inshore (18-27 m) stations (Fig. 2). 

 Larger individuals inhabited greater depths. In fact, 

 the mean size of white croaker was successively 

 larger as depth increased (ANOVA, F = 284.2, P < 

 0.001). 



Age and Growth 



Lengths at ages were estimated by direct observa- 

 tion of otolith annuli and through the von Bertalanffy 

 growth curve model 



L t = L x [1 - exp -k {t-t )\ 



= length at time t 

 = theoretical maximum length 

 = constant expressing the rate of ap- 

 proach to L x 

 = theoretical age at which L, = 



to the direct observation age-length 



was fitted 

 data. 



We transformed male and female growth equations 

 to linear form (Allen 1976) and compared these by 

 analysis of variance. Females were found to grow 

 significantly faster than males (F = 16.8, P < 0.05), 

 hence we separated growth data by sex (Table 4). 



TABLE 4.— Parameters of the von Bertalanffy equation for 

 white croaker off southern Calfornia. 



The oldest male and female white croaker we 

 examined were 12 yr old (Fig. 3). Females grew 

 slightly faster than males and reached a greater size. 

 Females from age 1 (at which over 50% of the fish 

 were mature) outgrew males. 



White croaker grew at a fairly constant rate 

 throughout their lives, exemplified in their very low/? 

 values. No asymptote was reached within the observed 

 12-yr life span. Thus, the maximum predicted 

 lengths were longer than both published (41.4 cm 

 TL, Miller and Lea 1972) and unpublished (44.2 cm 9 ) 

 records, although the r values for the von Bertalanffy 

 equations were high (0.84 for both sexes). 



Length - Weight Relationships 



A total of 58 1 males and 665 females from southern 

 California and a total of 94 males and 161 females 

 from Monterey Bay were weighed and measured. 

 The relationships between total length and weight fit 

 the relationship W = aL h , where W = weight in 

 grams, L = total length in centimeters, and a and b 

 are constants, with values determined using log 10 

 transformation and fitting the values to a straight line 

 by least squares (Figs. 4, 5). In southern California, 

 males tended to be heavier at a given length than 

 females (analysis of variance, F — 10.18, P < 0.01), 

 whereas off Monterey no significant difference was 

 found (analysis of variance, F = 0.67, P > 0.4). To 

 test whether this difference was an artifact caused by 

 seasonal and gender-related factors, we subtracted 



'R. N. Lea, California Department of Fish and Game, 2201 Garden 

 Road, Monterey, CA 93940, pers. commun. May 1982. 



183 



