RALSTON and WILLIAMS: AGEING OF TROPICAL FISHES 



400 



o 



c 



V 



c 



V 



1 50 200 



250 



300 



350 



400 



450 



500 



Fork Length (mm) 



Figure 7.— Combined length-frequency distribution for all gindai sampled. 



CO 





E 

 E 



en 



c 



0) 



o 



Li_ 



c 



D 



500 



380 390 400 410 420 430 440 450 460 470 

 Full Vulnerability Cutoff Point (mm) 



Figure 8.-Wetherall et al. (1987) regression of I, on f ,, (see text for further discussion). 



mated to be 2.39 and L„ = 466 mm FL. Confi- 

 dence intervals for these estimates are P(1.94 < ZIK 

 < 2.62) = 0.95 and P(458 < L„ < 474) = 0.95. 



With the results presented earlier, it is possible 

 to decompose the ZIK ratio and estimate total 

 mortality rate (Z). Fori^T = 0.234 yr"' (increment 

 microstructure), Z = 0.56 yr', and for ii" = 0.156 

 yr-^ (annual marks), Z = 0.37 yr-^ 



Spawning Season 



Gonadosomatic indexes for male and female gin- 

 dai are summarized by month of capture in Figure 

 9. The relative size of gindai ovaries was consider- 

 ably greater than the testes. More importantly, 

 there was a distinct seasonal trend in the monthly 

 mean gonadosomatic indexes of females, which 



