Brodziak and Macy. Growth of Loligo pealei 



225 



3.97=F 005 (1,74)). The best curve for pooled-sex 

 samples hatched during June-October was the case- 

 II curve which was selected over the case-IV curve 

 because the hypothesis a=0 was rejected (/= 18.64 > 

 3.91=F 005 ( 1,142)). The best curve for pooled-sex 

 samples hatched during November-May was the 

 case-Ill curve which was selected over case-IV curve 

 because the hypothesis a-0 was rejected (/"=6.82 > 

 3.89=F 005 ( 1,205)). For each of the 6 other subsets of 

 length-at-age data, case IV yielded the best growth 

 curve (Table 9). 



For the weight-at-age data, case-II growth curves 

 were chosen for pooled-sex samples (Fig. 4B) and 

 pooled-sex samples hatched during June-October 

 (Fig. 5B). Although these curves are sigmoidal and 

 eventually approach an asymptote (cf. Schnute, 

 1981), it is important to note that the asymptotes 

 are not approached within the range of data for the 

 estimated curves and that growth is nearly exponen- 

 tial for the observed ages. In contrast, a case-Ill 

 growth curve was chosen for pooled-sex samples 

 hatched during November-May (Fig. 5B). This 

 growth curve is not asymptotic and consists of an 

 initial period of decelerated growth followed by a 

 period of accelerated growth after a certain size is 

 reached. 



Case-IV growth curves were chosen for every data 

 set where the weight-at-age data were partitioned 



by sex, with one exception. Growth in weight was 

 exponential for female and male samples (Fig. 7B). 

 Similarly, exponential growth was evident for female 

 samples hatched during June-October and during 

 November-May (Fig. 8B) and for male samples 

 hatched during June— October and during November- 

 May (Fig. 9B). In contrast, a case-II curve was cho- 

 sen for indeterminate-sex squid (Fig. 6B), although 

 growth rate was effectively exponential for the ob- 

 served ages. In this case, the estimated curve would 

 approach an asymptote outside the range of possible 

 sizes for L. pealei that lack identifiable sexual char- 

 acteristics. 



For adult squid, the estimated growth curves in- 

 dicated sexual dimorphism. Length-at-age curves for 

 female (L F ) and male (L M ) samples were 



L F (d) = 2.3343e 



u.nmd 



L M (d) = 0.7470e 



1)1114",/ 



(10) 



where L is mantle length in centimeters and age (d ) 

 is measured in days (Fig. 7A). Similarly, weight-at-age 

 curves for female (W F ) and male (W M ) samples were 



W F (rf) = I.1446e 



0.0182d 



W M (d) = 0.1316e 



(UOllrf 



(11) 



