On the breeding areas of the Swordfish (Xip/,ia.,) 44^ 



a specimen taken in May of 192 mm (Arata, 1954) should be about 2 years old 

 Th,s appears however to be far too slow a growth rate for a voracious species such as 

 the swordfish. Unfortunately, Nakamura (1951) did not record the nK-asuremcnts 

 of a rather large number of individuals of roughly this size found in the stomach 

 contents of spearfish, measurements which would have provided some useful supple- 

 mentary data on the growth rate of Xiphias. No further information is available on 

 the growth although it is probably very fast, for such a predator, which, in the Pacific 

 may weigh up to 680 kgs. 



The 



Table HI 

 size of swordfish fry in different months based on the data 0/ Arata (1954) 



and the Danish material 



Size 

 mm 



Month 



I If III IV V VI VII VIII IX X XI XII I II III n y y, 



80-84 

 75-79 

 70-74 

 65-69 

 60-64 

 55-59 

 50-54 

 45-49 

 40-44 

 35-39 

 30-34 

 25-29 

 20-24 

 15-19 

 10-14 

 5-9 



I 



2 1 



2 2 3 



2 9 13 



I 



3 

 3 

 9 

 1 



2 

 2 



1 1 2 

 1 2 



I I 



The stomach contents of young stages indicate that the fry in the postlarval stages 

 very soon progress from a copepod to a pure fish diet. Indeed, they often prey on 

 close relatives (Arata, 1954). To show how greedy this species is even in very early 

 stages, we need only refer to Fig. I. It shows a postlarval specimen of about 8 mm 

 which has swallowed another fish larva, almost as large, so that the specimen appears 

 to have eyes at both ends. The prey was swallowed head first. This was also the case 

 in three other Xiphias specimens from the same haul with the prey in various stages 

 of digestion. This exceptional catch of 5 postlarval specimens of 7-9 mm in one net, 

 four of which were stuffed with food, suggests that they had become sluggish as a 

 consequence. Thus, this may explain why so many were taken at one time. Normally, 

 the majority would have escaped the net. Thus, it appears that even such small 

 individuals must be very swift swimmers. 



From our study, it is apparent how little is known of the breeding places, although 

 it is clear that spawning takes place over all oceans where the surface temperatures 

 are more than 23^-24' C. Little is known of the fry's migration away from the 

 principal breeding areas and of the mature fish's migrations except in certain coastal 

 areas. For example, it is not known whence come the migrants to northwest Euro- 

 pean waters during the summer and fall months, whether from the stock in the vicinity 

 of the Iberian peninsula and the Mediterranean or from that of the western Atlantic. 



