DeMartini et al.: Maturity, size, and sex composition o\ Xiphias gladius 



491 



250 



Females 



150 - 



I 1 Total 



Mature 



^^ Acliue 



Spawners 



Jan Feb Mar Apr May Jun Jul 

 Month 



B 



Aug Sep Oct Nov Dec 



Males 



Total 

 Q2S^ Mature 

 Active 



.Ob- 



JU 



ri- 



Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

 Month 



Figure 1 



Numbers of (A) female and (Bi male swordfish iXiphias gladius) that were 

 immature, mature, active, or imminent spawners (females onlyt. which were 

 caught on occasional research cruises and by the Hawaii-based pelagic long- 

 line fishery each month during March 1994^une 1997. Maturity and repro- 

 ductive activity were assessed based on gonad developmental stages scored 

 histologically. 



yolked oocytes undergoing a-, or p- and later atresia (Table 

 1). Female individuals were designated as "immature" 

 if their most advanced oocytes were unyolked or only 

 partly to moderately yolked without substantial atresia, 

 or as "mature" if their most advanced oocytes were fully 

 yolked with or without atresia ("active-mature") or if their 

 most advanced oocytes were less than fully yolked but 

 with alpha or beta atretic stages present. Developmental 

 stages were further described according to the diameters 

 of the largest size class mode of oocytes present. Among 

 mature females, fish were deemed "ripening mature" if fully 

 yolked but lacking HYDs or POFs. "ripe mature" (immi- 

 nent spawners) if POFs or HYDs were present, or "resting 

 mature" if a majority of yolked oocytes were atretic. 



Oocyte diameters were measured by using formalin- 

 fixed whole oocytes or oocyte cross sections on histolog- 

 ical slides. For formalin-fixed specimens, diameters of 

 25 of the largest oocytes were measured with a dissect- 

 ing microscope (random axis, 25-50x). The median of 

 25 random diameters provides a cost-efficient estimator 

 of average maximum oocyte size for multiple-spawning 

 fishes ( Lau and DeMartini. 1994 ); swordfish are multiple- 

 spavvners (Uchiyama and Shomura. 1974; Arocha. 1997). 

 Histological slides were prepared for a random subset 

 of these specimens; diameters of oocyte cross sections 

 on slides were measured at 60-.300x and for each fish 

 ovary examined, maximum and minimum diameters were 

 averaged for 5-10 of the largest oocyte sections present 



