FISHERY BULLETIN: VOL. 87, NO. 1 



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Figure 6.— The seasonal occurrence of hyaline and opaque markings on the margins of gindai otoliths. 



parameters of the von Bertalanffy growth equation 

 by means of a Walford plot (Ricker 1975), wherein 

 results from a regression of FL at time t + 1 against 

 FL at time t provide the basis for estimates of K 

 = 0.156 yr-' and L„ = 537 mm FL. 



Length-Frequency Analysis 



The combined length-frequency distribution for all 

 gindai sampled (Fig. 7) shows that the mean size was 

 368 mm FL (standard deviation = 48.1 mm). Fish 

 ranged in size from 190 to 490 mm FL and the modal 

 size was 380 mm FL. Thus, l^j„^„ was estimated to 

 be 385 mm FL. There is evidence to show that, 

 above this size, fish were equally vulnerable to the 

 gear (Ralston 1982, unpubl. data), although smaller 

 individuals were almost certainly underrepresented 

 in the catch because of the selective sampling ac- 

 tion of the fish hooks. As f^.i increased from^385 

 to 485 mm FL, the corresponding value of f, in- 

 creased (Table 4). Due to a sample size of one, 

 estimates of the variance and standard error of the 

 mean could not be calculated when f ^, = 485 mm. 

 Without a statistical weight, the point was excluded 

 from the analysis. 



The regression of f, on f,, (Fig. 8) was highly 

 significant (P « 0.0001), although there was an 

 increasing lack of fit as t ^^ increased, especially 

 beyond 435 mm FL. This result was due to the 

 diminished statistical weights accorded these points 

 (Table 4). Estimates of the slope and intercept of 

 the regression were 6 = 0.7051 and i = 137.31, with 

 standard errors of 0.0200 and 8.138, respectively. 

 Thus, the mortality to growth ratio (ZIK) is esti- 



Table 4.— Length-frequency data fitted to the W/etherall et al. 

 ( 1 987) regression model for estimating ZIK and L^ (fork length in 

 mm). 



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