From the beginning of the expedition until June 14, a total of 36 striped 

 marlin and 7 broadbill swordfish were taken. These were measured from 

 length, girth, and weight by Mr. John Manning and Mrs. Thuet. Gonads 

 were also measured and samples preserved for microseopical examination. 

 Surface water temperatures and meterological data were taken during the 

 entire time spent at sea. 



Mr. Luis R. Rivas took charge of the field work June 5, and with the 

 assistance of Mrs. Thuet, continued to make morphometric studies of the 

 billfish in greater detail and initialed a series of otTshore cruises for the 

 purpose of taking plankton samples for the purpose of life history studies. 

 On June 15 and 16, five stations were occupied, about 20 miles apart on a 

 line running due west of Iquique for about 100 miles. Plankton samples 

 were rich and surface temperatures fairly uniform between 16°C and 

 17.5°C. All billfish sighted were recorded. 



Towards the end of June the number of billfish sighted dropped rapidly 

 and the next offshore traverse was accordingly made from Arica. Plankton 

 and hydrographic samples were taken at stations about 5 miles offshore, 

 about 40 miles apart, between Iquique and Arica; at stations 20 miles apart 

 along a line extending 100 miles due west of Arica; two, about 40 miles 

 apart on a 20° course from a point 100 miles west of Arica; and at a point 

 about 25 miles due west of Punta Pichalo. Surface temperatures were 

 almost entirely within a range of 15^C to IT^'C. Additional specimens of 

 billfish were obtained from commercial fishery operations at Arica. 



A third offshore cruise was made during June 30 to July 2 to the south 

 of Iquique. Two stations were occupied at points about 40 miles apart on 

 a course of about 245° extending from Iquique to a point approximately 

 100 miles due west of Punta Lobos. Six stations were occupied at points 

 about 20 miles apart on the line due west of Punta Lobos. A further station 

 was located about 5 miles west of Punta Banancos. The plankton samples 

 obtained during this cruise were particularly rich in larval and juvenile 

 fishes and adult lantern fishes (myctophids) up to three inches long were 

 captured. Surface temperatures were within a range of 14.5°C to 17°C. 

 Observations were made on billfishes, whales and giant squid, which are 

 very abundant in this area. 



Among other interesting observations, the feeding habits of the thresher 

 shark (Alopias) were studied at close range oft' Arica. The presumed use 

 of the long tail for slapping and stunning fish (bonito) was actually con- 

 firmed by direct observation. Through the cooperation of Messrs. Scheib 

 and Navarro of the fish cannery at Iquique, specimens of various species 

 of scombrid fishes from adjacent waters were donated to the expedition 

 for study. These included various species of tuna and bonito whose racial 

 characteristics were hitherto unknown. While the Explorer was underway 



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