Calkins, T.P. 1961. Measures of population density 

 and concentration of fishing effort for yellowfin 

 and skipjack tuna in the eastern tropical Pacific 

 Ocean, 1951-1959. Inter-Am. Trop. Tuna Comm . 

 Bull. 6:69-152. 



Tuna catch data were analyzed to demonstrate 

 seasonal changes in the geographic distribu- 

 tion of catch per unit effort in the skipjack 

 fishery. Pronounced seasonal fluctuations 

 were noted in density with higher values in 

 the third and fourth quarters of each year 

 for skipjack. This pattern was not present 

 in yellowfin indices. Mentioned unusual 

 oceanographic conditions of 1957, 1958, and 

 1959 coinciding with abnormal range varia- 

 tions of the fishery with increased catches 

 at the north and south extremes and decreased 

 catches in the middle. 



KEY WORDS: tuna, skipjack, yellowfin, catch, 

 area, season, oceanography. 



Caviedes, C.N. 1973. Secas and El Nino: Two simul- 

 taneous climatical hazards in South America. Proc. 

 Assoc. Am. Geogr. 5:44-49. 



El Ninos off Peru and Secas (droughts) off 

 northeast Brazil appeared simultaneously and 

 a linkage between them seems to exist. Both 

 depend on the position of the intertropical 

 convergence and the subtropical high pressure 

 cells of the Pacific and Atlantic Oceans. 

 Cloud analysis of satellite pictures of 

 normal years suggested that a mechanism of 

 linkage is the reason for the simultaneous 

 occurrence of the two events. 



KEY 

 sphe 

 rents . 



WORDS: oceanography, meteorology, atmo- 

 re, sea surface temperature, season, cur- 

 s. 



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