so far as known none have been taken there by anglers. However, inter- 

 views with commercial fishermen revealed that at least a few specimens are 

 taken by them every year. These men can distinguish well between the 

 striped and black marlin and refer to the latter as "pez zuncho." 



Twenty-six specimens of black marlin were measured by the expedition 

 in Peruvian (Cabo Blanco) waters, thanks to the splendid cooperation of 

 various other anglers whose catches were kindly donated for study. 



All of the 26 specimens of black marlin available for study in Peru were 

 measured and dissected. Vertebrae were obtained for age studies and the 

 gonads and stomach contents analyzed. These specimens ranged from 418 

 to 1085 pounds in weight (average 770 pounds) and 2755 to 3475 mm. in 

 fork length (measured from tip of lower jaw). Of the 26 specimens sexed, 

 only 1 (4 per cent) was a male, and 25 (96 per cent) females. All the 

 gonads examined appeared to be in a resting condition far from the ripe 

 or recently spent stage. This would seem to indicate that black marlin were 

 not in the process of spawning off northern Peru during the period of 

 operation of the expedition. The females were considerably heavier (aver- 

 age 783 pounds) than the single male (445 pounds). 



The sex ratio found in black marlin from Cabo Blanco and the apparent 

 much larger size of the females suggest that the latter might not occur in 

 company with the males except during the as yet unknown spawning sea- 

 son. In this connection, it is interesting to note that three specimens ex- 

 amined in Panama during July 14-16, 1953, ranged in weight from 200 

 to 366 pounds and were all males. In addition, interviews with local com- 

 mercial fishermen and anglers familiar with the area, reveal that black 

 marlin are much more abundant in the Cabo Blanco area during June 

 through November, and very scarce or absent the rest of the year. The 

 simultaneous occurrence of mostly females in Peru and mostly males in 

 Panama during July is suggestive. 



Whether or not the black marlin occurring in Peru form part of the same 

 race or population as those occurring in more northern waters has not as 

 yet been established. It is hoped that the biometric data obtained in Cabo 

 Blanco may help in the solution of this problem. In addition, the oceano- 

 graphic data obtained correlated with the occurrence of the fish in Peru- 

 vian waters and nearby areas, is expected to throw light on their migratory 

 movements. 



Examination of the stomach contents of the black marlin studied 

 revealed a wide variety of food. Jack crevalle (Caran.x hippos) were found 

 in 7 stomachs and was the fish most frequently occurring in the stomach 

 contents. Sometimes the stomachs would contain only this species and as 

 many as 4 large jacks would be found in a single stomach. It is interesting 

 to note that the occurrence of jack crevalle in Cabo Blanco waters was 



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