Fishery Bulletin 90(4), 1992 



20 

 10 



l^ 



5 - 



CLASS 3 

 n = 975 



40 



20 



> 15 



S ^ 



lU 



c 



u. 



% 



I I I I I I I I I I I I M I M I I M I I ] I I I I M I 1 I I I I M I I I I I 



200 400 600 800 1000 1200 



CLASS 4 

 n = 950 



I I I I I I I I I I ' " I I I I fi "I I I ' I ' I I I ' ' ' I ' I I I ' ' ' I " I I 

 200 400 600 800 1000 1200 



I I I i| II i| 

 1000 1200 



'I " 'I 

 200 400 600 800 1000 1200 



OOCYTE DIAMETER {urn) 



Figure 2 



Percent frequency of oocyte diameters for swordfish Xiphias 

 gladius collected during the spawning season off southeast 

 Florida with ovaries in Classes: (3) Maturing, (4) Mature. (5) 

 Gravid, and (6) Spawning/Partially Spent (see "Methods and 

 materials"). 



group of oocytes proceeds through final maturation and 

 represents the clutch (Wallace and Selman 1981) to be 

 shed during the next spawning event. 



The reproductive season for swordfish is protracted. 

 Mature or actively spawning females were found dur- 

 ing each month sampled, except January. Gravid or ac- 

 tively spawning males were found during all months 

 sampled (Fig. 3). The greater numbers of spawning fish 

 taken from late-spring to midsummer suggests in- 

 creased spawning activity then. In addition, mature 

 swordfish show a sharp increase in their maximum 

 oocyte diameters to >800^m beginning in April and 

 extending through July, indicating peak spawning 

 activity then (Fig. 4). 



Histological features (postovulatory follicles and 

 hydrated oocytes) provide evidence for active sword- 

 fish spawning off the Atlantic coast of Florida from 

 about 24°40'N in the Straits of Florida southwest of 



Duck Key to about 28°25'N just west of Cape Canaver- 

 al (Fig. 1). The easternmost location where fish in 

 spawning condition were collected was 16 km east of 

 Grand Bahama Island at 480 m depth. About 25% of 

 the fish collected at the westward extent of our sam- 

 pling area (about the 200 m contour) exhibited evidence 

 of recent or imminent spawning. 



There was a preponderance of smaller males in our 

 spring and summer samples. Overall, males significant- 

 ly dominated the catch (345 M:216 F; x'- 29.7, df 1, 

 P<0.001); although at sizes >200cm, females signifi- 

 cantly outnumbered males (22 M:67 F; x" 22.8, df 1, 

 P<0.001). There was no histological indication of 

 hermaphroditism throughout the 72-281 cm length 

 range. During spring and summer, males were domi- 

 nant (266 M:152 F; r 31.1, df 1, P<0.001); but dur- 

 ing the fall and winter there was no significant differ- 

 ence in abundances of sexes (79 M:64 F; x" 1.6, df 1, 

 P>0.05). 



The batch fecundity of the seven swordfish sampled 

 was 1.4-4.2 million eggs for swordfish 177-281 cm 

 and 69-268 kg (Table 4). There was no obvious rela- 

 tionship between our estimates of batch fecundity 

 and length or weight. The correlation coefficients 

 between batch fecundity and length (r 0.21) and be- 

 tween batch fecundity and weight (r 0.64) were not 

 significantly different from zero (table of critical values 

 for correlation coefficients, df 5, P>0.05, Rohlf and 

 Sokal 1981). 



Discussion 



Sizes-at-maturity have been reported for swordfish in 

 the Atlantic and Pacific Oceans and Mediterranean 

 Sea (Ovchinnikov 1970, Berkeley and Houde 1984, 

 DeMetrio et al. 1989). However, in these reports 

 maturity was determined by visual inspection of 

 gonads, and no explanations were given as to whether 

 the sizes reported were for first maturity or for 50% 

 maturity. Berkeley and Houde (1984) reported that 

 western Atlantic male and female swordfish mature at 

 ~21kg and 74 kg, respectively. This corresponds 

 closely to the lengths-at-50%-maturity we present for 

 swordfish off southeast Florida. Using equations in 

 Table 1, we determined 50% maturity of males at 18 kg 

 (112 cm LJFL converted to whole weight) and 50% 

 maturity of females at 77kg (182cm). Ovchinnikov 

 (1970) reported that male swordfish "reach maturity" 

 in the Atlantic at about 100 cm (type of measure 

 unknown). However, he reported a smaller size-at- 

 maturity for females (70cm). DeMetrio et al. (1989) 

 reported that male swordfish in the eastern Mediter- 

 ranean Sea first begin to mature at 82- 105 cm LJFL 

 and that nearly all are mature when > 135cm. Females 



