NOTE Rom^n-Rodriguez and Hammann: Age and growth of Totoaba macdonaldi 
621 
Figure 1 
Location of sampling sites in the northern upper Gulf of California. (▲) = adults; juve- 
niles were collected within the 40-m depth contour. 
tral arm of the sulcal groove. The relation between 
otolith radius and fish length was fitted by using the 
Gompertz function (Ricker, 1979) and the computer 
program Fishparm 3.0 (Prager et al., 1989). To de- 
termine size at ages that were not collected, we 
backcalculated past ages following Bagenal and Tesch 
(1978) and Jerald (1983), using the Gompertz relation 
between OR and SL, not the otolith length to fish length 
regression. 
A von Bertalanffy growth model (VBGM) was fit- 
ted to the observed SL at the midpoint of each age 
group represented in our sample (n=101) and also to 
the back-calculated sizes (n= 346) determined from 
81 otolith thin sections, by using the computer pro- 
gram Fishparm 3.0 (Prager et al., 1989). The growth 
equation was calculated for pooled sexes because ju- 
veniles can be sexed only by using histological tech- 
niques; age and length differences between males and 
females have not been reported in the literature. 
Three juveniles captured in trawl nets during July 
and August 1989 were kept alive and transferred to 
the Centro Ecologico de Sonora Research Aquarium 
(Hermosillo, Sonora, Mexico); (see Almeida Paz et al. 
[1990] for more details). One fish died after almost 
12 months of captivity; the other two were sacrificed 
24 months after capture. Lengths and weights of 
these fish were taken every month beginning five 
months after capture. These lengths and the ring 
counts found in the otoliths of these fish were used 
to validate annual otolith ring deposition. 
