496 



Fishery Bulletin 98(3) 



150 r 



100 



50 



00 



Stage I 



Pre-vltellogenic 



n= 138 



1 6 



Diameter (mm) of largest oocyte size mode 



Figure 4 



Size distribution of oocyte stages in ovaries of swordfish iXiphias 

 gladius) caught by the Hawaii-based pelagic longline fishery 

 during March 1994-June 1997, which were examined histologi- 

 cally. Diameters (mm) are for the largest size class mode of viable 

 (not atretic) oocytes present. Sample sizes refer to the numbers of 

 specmiens with ovaries in each stage. 



f=23.1: df=l; P<0.001). The relative numbers of active 

 females and imminent spawners were independent of 

 moon phase i Table 4 ), although indicating no lunar spawn- 

 ing periodicity. Eighty-two percent of all reproductively 

 active (stage 4) males were caught during March-July. 

 Many imminently spawning females were caught within 

 several hundred km of the Hawaiian Archipelago (Fig. 6), 

 not far beyond the borders of the 75- and 50-mile closures 

 to pelagic longlining in the main Hawaiian and North- 

 western Hawaiian Islands, respectively. 



Size, sex, and maturity composition of catches 



The size and sex composition of swordfish catches were 

 related (Table 5; Fig. 7). Most (0.55) of the swordfish caught 

 that were <140 cm were male, most (0.(i4) of those >150 

 cm were female, whereas the sex ratio (females/total) of 

 fish between 140 and 150 cm EFL was indistinguishable 

 from 0.5 (Fig. 8). Sex ratios fluctuated around 0.5 without 

 pattern at lengths <1()0 cm, were, an increasing power 



function of fish length between 100 and 220 cm (propor- 

 tion female=0.0018£FLi '^i«: r-=0.87; ;i=24 5-cm classes; 

 P<0.001) and were consistently >0.9 at lengths >220 cm 

 EFL (Fig. 7). Overall, males represented about 39.5'^f of 

 the March 1994-June 1997 observer-sampled swordfish 

 catch by weight. The female catch by weight was 60.59^ . 



The maturity composition of swordfish catches differed 

 between the sexes. During March 1994-June 1997, mature 

 fish represented about 56'/, and 77'r of the sampled female 

 catch in terms of numbers and weight, respectively. Mature 

 fish comprised 88'7f (numbers) and 96'7( (weight) of the 

 sampled male catch. Overall, 71*7, and SS'Tr of the total 

 sampled catch (both sexes) were mature by numbers and 

 weight, respectively. 



Both the sex and size composition of swordfish catches 

 varied spatially (Fig. 9; Table 6). Latitude had a stronger 

 influence on sex ratio and size composition than did longi- 

 tude (Table 6, A and B). A large majority (61'f ) of all sword- 

 fish caught south of 27"N were males. The body size (hence 

 sex) of swordfish caught might vary with depth and time 



