~r 



■30°N 



-20° 



LONG DISTANCE MOVEMENTS OF 



TAGGED STRIPED MARLIN 



1963 TO 1968 



160° ^Christmas I 



J I 1 l_ 



140° 130° 



_l I I 



120° 



110° 



J L_ 



1968 RECOVERIES OF 

 TAGGED STRIPED MARLIN 



-20° N 



Revilla Gigedo Islands 



115° 



100° 



L 



MEXICO 



Figure 7. — Movements of tagged striped 

 marlin in the eastern Pacific Ocean. 



western Arabian Sea (Fisheries Agency of Japan, 

 Research Division, 1969-72). 



3.52 Schooling 



Striped marlin, like the other istiophorids, do not 

 form dense schools like the tuna, and the individuals 

 are usually dispersed at wide intervals (Nakamura, 

 1949). Frequently, however, several fish are seen 

 together; sometimes following one another, especially 

 during the spawning season. 



Surfacing is apparently more common when the 

 wind and waves are high. When wind and current are 

 moving in the same direction, the surface is calm and 

 few fish are seen at the surface. When the wind runs 

 counter to the current, high waves result, and fish are 

 most often seen at the surface and are usually swim- 

 ming in the direction of the wind, at least in Formosan 

 waters (Nakamura, 1938). 



When surfaced, the striped marlin usually is swim- 

 ming very slowly with the upper caudal lobe above the 

 surface and the dorsal fin retracted and not showing. 

 This characteristic reportedly distinguishes them 

 from swordfish which are unable to depress the dorsal 

 fin and show both the dorsal and caudal fins when 

 surfaced. Striped marlin swim faster and are less easi- 



ly approached when surfaced than the swordfish 

 (Philippi, 1887). 



Little is known about how far the fish move ver- 

 tically. Saito et al. (1972) report that striped marlin 

 have been caught at 150- to 290-m depths by vertical 

 longline experiments in Fiji waters. 



For composition of stocks by size see also section 

 2.22. As mentioned previously, there is considerable 

 variation in size composition between various regions 

 and particularly between the northern and southern 

 groups in the Pacific (see, for example, Howard and 

 Ueyanagi, 1965; Koga, 1967; and Kume and Joseph, 

 1969b). As mentioned earlier, southern fish tend to be 

 larger than northern fish throughout the Pacific. Size 

 composition of striped marlin in the Indian Ocean 

 resembles the North Pacific size distribution more 

 than the South Pacific. 



Striped marlin "schools" occur in waters in com- 

 mon with the schools of most of the Indo-Pacific 

 scombroids, particularly albacore, yellowfin tuna, and 

 bigeye tuna, Thunnus obesus. 



3.53 Responses to stimuli 



Very little is known of this subject as it relates to 

 striped marlin. The possible response to temperature 



148 



