SEX COMPOSITION OF THE TUNA CATCHES 



There was a preponderance of males among the yellowfin taken 

 during 1953. As in past samples (Murphy and Shomura 1955), the 

 sexes were about equally represented in the 1953 yellowfin catches up 

 to 137 cm. (110 lbs.), and above this size males clearly predominated 

 (fig. 11). 



175 ry^ 



The bigeye 

 (fig. 12) also showed 

 an unbalanced sex ratio 

 but the 1953 samples 

 include too few fish to 

 yield a satisfactory 

 description. There is 

 a tendency, however, 

 for males to dominate 

 among fish larger than 

 122 cm. (85 lbs.). 

 Among the larger alba- 

 core, males definitely 

 dominate (fig. 12), but 

 again the samples are 

 too small to describe 

 the sex ratio adequately 

 at all sizes. Of the 66 

 skipjack taken in 1953, 



30 were females, and there was about even representation throughout the 



lengths captured (47-85 cm. = 5-34 lbs.). 



107 117 127 



LENGTH (CM ) 

 50 75 100 



APPR0X WEIGHT (LBS) 



150 175 200 



Figure 1 1. --Yellowfin size distribution by sex, 

 1953 (data in appendix table 15). 



CHANGES IN LONGLINE GEAR 



Three basic innovations were made to the longline gear during 

 1953 (Mann MS). The first was shortening the droppers in order to 

 reduce construction costs and handling labor. The second was the 

 insertion in the mainline of a wire link to which the dropper is snapped, 

 an improvement designed to reduce the number of tangles. Finally, an 

 attempt was made to discover the optimum hook spacing along the main- 

 line. These changes are interrelated and their development was to 

 some extent simultaneous, but for the sake of clarity we will consider 

 each separately. 



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