Lozano-Alvarez et al.: Fishery, growth, and movements of Panulirus argus 



83 



A 



(a) 

 D Males n = 2074 

  Females n =18 19 



^ •  



10 30 50 70 90 110 130 150 



Carapace length (mm) 



10 20 30 40 50 60 70 80 90 100 110 120 

 Carapace length (mm) 



Figure 4 



Size-frequency distribution of Panulirus argus caught in Bahfa 

 de la Ascension for tagging purposes in (a) 1985 and (b) 1986. 

 Tags were applied to lobsters >44mm CL, as indicated by 

 arrow. 



range 22.0 - 113.1 mm). However, the tagging opera- 

 tion in 1985 occurred one full month earlier than in 

 1986. 



The means of CL of lobsters caught in each of the 

 six sampling zones during 1985 and 1986 (Figs. 6, 7) 

 were significantly different (P<0.05, approximate 

 test of equality of means when the variances are 

 heterogeneous; Sokal and Rohlf 1981, Box 13.2). An 

 unplanned comparison among pairs of means (Sokal 

 and Rohlf 1981) shows three groups of mean sizes in 

 each year (Table 1). This result implies that the distri- 

 bution of lobsters by size in the bay is not random. 

 Smaller lobsters occupied the more interior of the six 

 sampling zones (zones II, III, and IV), and larger 

 lobsters occupied zones closer to the reef (zones I, V, 

 and VI). 



Growth and recruitment 



Of the 849 lobsters recaptured during 1985-86 and the 

 407 recaptured during 1986-87, only 372 and 268, 

 respectively, were returned with accurate CL informa- 

 tion. All but two showed growth between tagging and 

 recapture. 



During the first three months of the 1985-86 season, 

 the modal CL of recaptured males increased 10 mm. 

 Growth of individuals was highly variable (Fig. 8) and 

 in some cases indicates more than one molt occurred. 

 For females (data not illustrated), the mode increased 

 8mm. 



Fabens' method (1965) for estimating growth param- 

 eters was used for both sexes and both years separately 

 (Table 2a). The estimates of asymptotic length and 

 the growth coefficient k by this method show great 

 variability. 



On the other hand, the EM algorithm needs some ini- 

 tial estimates before it can begin iterating, and the 

 Fabens estimates were used for this. A set of data for 

 males and females for each year was thus obtained 

 (Table 2b). Combining the data over both years, for 

 each sex, did not lead to a significant increase in the 



