48 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Table 1. — Weight and stage of maturity of 112 yelloiofln tuna from the Hawaiian longline fishery, January-December 1950 



1 For classification of the stages of maturity, see p. 51. B Maturing ovaries in which some ova had been lost through previous spawning earlier in the season. 

 * Fish weights unavailable. ' Ovaries not Intact. 



Longline gear appears to select the larger, adult 

 fish; hence, the smaller, sexually immature fish 

 are not represented in the collections, which in- 

 clude the size range 36.3 to 94.3 kilograms (80 to 

 208 pounds) . 2 



"Yellowfin tuna weighing between 15 and 60 lbs. are caught 

 rather infrequently in Hawaiian waters. Longline gear, which is 

 specifically designed to capture large fish, seldom takes yellowfin 

 tuna smaller than 60 lbs. Trolling gear, which is less selective 

 of fish size, catches very few of the 15-to-60-lb. size group, even 

 though the amount of fishing effort is substantial throughout the 

 year. Small yellowfin tuna from 2 to 20 lbs., but no larger, some- 

 times are captured in great numbers by the pole-and-line bait 

 fishery for skipjack. The virtual absence of the maturing size 

 group (15 to 60 lbs.) in the Hawaiian tuna landings suggests 

 that most members of this segment of the population migrate else- 

 where to mature, and only the adult sexually mature fish frequent 

 local waters. 



The date, weight of fish, locality of capture, 

 and state of sexual maturity, based on the criteria 

 established by Marr (1948), were recorded for 

 each sample. The ovaries, together with attached 

 peritoneal and vascular tissues, were carefully 

 removed from the fish. The posterior end of each 

 ovary was severed at its juncture with the oviduct, 

 and after all superfluous tissues were removed, the 

 ovaries were weighed on a triple-beam balance 

 to the nearest 0.1 gram and placed in 10-percent 

 formalin. 



Preliminary test measurements were made on 

 samples of 300 ova from the anterior, central, and 

 posterior parts of both ovaries from a near-spawn- 



