448 ^- Vedel Taning 



post-larval stages have been taken, we may assume that the spawning fish do not go 

 any deeper. 



In the southwestern North Atlantic Ocean surface temperatures between about 

 23-5° C and 28-1° C have been encountered at all localities where postlarval stages 

 have been taken. Surface temperatures of 24-5°-25-5° C are found during the breed- 

 ing season from February-April, and this temperature seems accordingly to be the 

 actual lowest spawning temperature. With the approach of summer the temperature 

 rises to 27° to 28° C or a httle higher, and then about October it begins to fall again 

 to about 25° C. 



In the Mediterranean Sea, the surface temperature where the one postlarva was 

 taken was 23-8° C (late September). As already mentioned, spawning apparently 

 takes place in the Mediterranean much later in the year than in the West Indies. 

 The reason for this is apparently that the temperatures favourable for spawning are 

 not high enough until somewhat later (in August it is about 23-3° C-26-5° C). 



In Indo-Malaya, the surface temperature at the places where postlarval specimens 

 were taken was generally higher than in the Atlantic (namely about 28°-29° C). In 

 the Pacific at the Marquesas it was however only about 26° C. 



Salinity. Young fry are known to exist at localities where the surface sahnities range 

 between about 33'8°/oo and 37-4°/oo; but the adult fish is found at very different 

 salinities, e.g. at 39°/oo in the Mediterranean and at 6°/oo in the Baltic. The species 

 thus tolerates a wide range of salinities, but it is not possible with the material at 

 hand to determine any correlation between salinity and the breeding habits of Xiphias, 

 other than that the salinity must apparently be higher than 34-00°/oo- Thus, in the 

 general area of the Caribbean, most of the fry have been taken in water with salinities 

 of about 35-9°/oo-36'7°/oo and in Indo-Malaya of about 33-9°/oo-35-5°/oo. 



Light. Since fry up to 4-5 cm in length have been taken at the surface of tropical 

 seas on clear, sunht days, and have also been taken there at night with artificial light, 

 this species lives close to the surface under varying light conditions in a manner 

 contrary to many other oceanic species. It is not definitely known how deep they can 

 live and thrive. 



GROWTH AND FOOD 



Very httle is known about the growth of the swordfish. So far as I am aware, 

 no one has made age analyses from the bones or otohths even in areas such as the 

 Mediterranean where small specimens are regularly caught. Sanzo (1922) has 

 reported on the growth under laboratory conditions of newly hatched larvae for a 

 period of ten days. 



A review of the postlarval specimens from West Indian waters (Arata's and the 

 Danish material combined), although based on fewer than 100 specimens, gives some 

 indication of the growth rate (Table III). Although the method of collection was not 

 the same and the intensity of fishing varied from month to month, it appears that 

 spawning as already mentioned is particularly intense during the early spring. Table 

 III seems to give a rather clear indication of the growth from the early stages (about 

 8 mm) in March-April to rather larger fry (approximately 23 mm) in July, and to 

 fry of about 70 mm in length by the next spring. To what extent the latter represent 

 the smallest of a larger and far more numerous 1-year group cannot be determined 

 without more material. If specimens of 5-8 cm are representative of the 1-year olds, 



