21 



the Maldive Islands chain. Albacore were taken only in waters 

 south of approximately latitude 15° S. but its distribution ex- 

 tended to the southern limit of the area surveyed, approxi- 

 mately latitude 37° S. 



The total catch from cruise 2 was 185 tunas, 35 billfishes, 

 87 sharks, and 70 miscellaneous fishes, including the un- 

 common pelagic ray and the moonfish. 



Zooplankton samples also were collected on the three 

 cruises of the Anton Bruun for use in studies related to our 

 secondary missions on the Indian Ocean Expedition. Although 



the tuna larva distribution studies have not begun, some pre- 

 liminary results are available from the study of copepods. 

 Some interesting distribution patterns have been noted in 

 several species of copepods of the family Candaciidae from 

 cruises 1 and 2. The presence or absence of these species 

 indicated that on the first transect of cruise 1, along longitude 

 70° E., three types of water were encountered. Moving from 

 north to south along the transect, Arabian Sea Water extended 

 from Bombay to latitude 9° N., Equatorial Water from latitude 

 9° N. to approximately latitude 11° S., and South Indian Ocean 

 Central Water from latitude 11° S. to the southern end of the 

 transect at approximately 37°S. The second transect (cruise 2) 

 along 80° E. did not present as clear a picture of the water 

 masses as the first, but the distribution of species of Candaci- 

 idae indicated that there was much mixing of all three water 

 types. 



The examination of zooplankton samples collected by the 

 Lament Geological Observatory on a cruise around the tip of 

 South Africa resulted in some new discoveries on the distri- 

 bution of certain species of copepods. Comparisons of the 

 morphology of the Atlantic and Indo-Pacific specimens of 

 Candacia pachydactyla indicated marked differences, suggest- 

 ing that these specimens represent two genetically separate 

 populations. The existence of two reproductively isolated 

 populations would suggest that equatorial species of Candaci- 

 idae from the Indo-Pacific are not transported into the Atlantic. 



In 1964 the data-collecting phase of the United States Pro- 

 gram in Biology will continue with the collection of biological 

 material and physical and chemical data on cruises 5 to 9 of 

 the Anton Bruun . On cruise 5 longline fishing will be carried 

 out along longitudes 55° E. and 75° E. Upon the completion of 

 cruise 5 we will analyze the data and samples from this and 

 from our earlier cruises and will then publish our findings. 



Figure 24. — Landing a large yellowfin tuna taken 

 by longline on the Anton Bruun (cruise 2). 



