152 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



ALBACORE 

 YELLOWFIN 



1954 



1955 



1956 



1957 



959 



I960 



Figure 1. — Total annual albacore and yellowfin landings 

 (tons) at the cannery in Samoa: 1954-60. 



The fishing grounds, which in 1954 and early 

 1955 were chiefly in the vicinity of Samoa and 

 to the north, have expanded to more distant and 

 southerty waters. This shift in fisliing grounds 

 has been accompanied by a shift in species com- 

 position of the catch from predominantly yellowfin, 

 Neothunnus macropterus (Temminck and Schlegel), 

 to albacore (fig. 1). The boats range great dis- 

 tances in all directions from Samoa (fig. 2). 



In August 1957, arrangements were concluded 

 with the management and staff of the Van Camp 

 Tuna Company to obtain gonad samples at the 

 cannery from 7 randomly selected albacore from 

 each landing. The fork length of each sampled 

 fish was measured to the nearest millimeter, using 

 a standard 1 )^-meter fish cahper, and the fish was 

 weighed to the nearest ji pound. The gonads 

 were removed and placed in plastic bags, appro- 

 priately labeled, then kept frozen until received 



by our Honolulu laboratory. Additional informa- 

 tion accompanj-ing each gonad sample included 

 the date of sampling, the fishing period (from 

 which it was possible to tell the probable month 

 of capture), and the locality of capture. 



Although emphasis in this study was placed on 

 the examination of ovaries, since previous studies 

 had indicated that testes are generallj' unsatis- 

 factory for the determination of developmental 

 stages (June, 1953; Otsu and Uchida, 1959b), 

 gonads of both sexes were collected in order to 

 msure complete randomness in sampling. 



The samples of gonads collected and shipped 

 to Hawaii comprised 1,772 pairs; the approximate 

 capture dates of the fish covered the period Jtily 

 1957 to September 1958 (table 1). The sampled 

 albacore ranged in size from 72 to 110 cm. (15 

 to 64 lbs.) (fig. 3). 



Table 1.- 



-Gonads collected at the cannery in Samoa, July 

 1957 to September 1968 



Date 



1957 



July 



August 



September 



October 



November 



December.- 



1958 



January 



February 



March 



April 



May 



June 



July 



August 



September 



Total 



Number of 

 testes 



118 

 77 

 81 

 73 

 58 

 91 

 95 



120 

 7 



LABORATORY PROCEDURE 



Upon arrival of the frozen samples from Samoa, 

 they were thawed and preserved in 10-percent 

 formalin. Laboratory examination of the for- 

 malin-preserved samples followed much the same 

 procedure used and described in detail by Otsu 

 and Uchida (1959b) in their study of North Pacific 

 albacore spawning. Each pair of gonads was 

 trimmed of extraneous tissue and weighed to the 

 nearest 0.5 gram. No furtlier work was done on 

 testes. The ovaries were sectioned and examined 

 under a microscope. The results of the previous 

 study of ova sizes and characteristics of the al- 

 bacore by Otsu and Ucliida (1959b) indicated that 



