Fish and the Weather 



In his Trade Wind Zone Oceanography Pilot Study of 

 1964-65, oceanographer Gunter R. Seckel compiled 18 

 months of data on oceanographic changes in the vicinity 

 of the Hawaiian Islands. He is now seeking to relate these 

 changes to conditions in the atmosphere. He has computed 

 heat exchange between the sea and atmosphere from the 

 Equator to lat. 35° N., and between long. 30° and 170° W. 

 This is a region dominated by the trade winds. He has 

 found that because of the prevalence of the trade winds, 

 the Hawaiian area is chiefly one in which heat is lost from 

 the ocean by the process of evaporation. Thus when the 

 ocean waters warm significantly, they do so not primarily 

 because of seasonal atmospheric changes in the immediate 

 area but because of advection — warmer waters have en- 

 tered the area from the south and southeast. 



The scale of this advection is related to the intensity of 

 the trade winds and the location of their center, he says. 

 These vary from season to season and from year to year. 



For the 12-month periods July 1963 to June 1964 and 

 July 1964 to June 1965, there were net heat los-ses from 

 the sea surface in the trade wind zone, although these 

 losses were different for the 2 years. Since the amount 

 of radiation from the sun and sky varies little from 

 year to year, the differences were due primarily to differ- 

 ences in the rates of evaporation and these, in turn, were 

 primarily due to differences in wind speed. 



FIGURE 18. The olbocore fishery based in Americon Samoa has grown 

 rapidly and spread over a vast area in the South Pacific Ocean. 

 Catch per unit of effort, however, is declining. This decrease, which 

 is appearing in other major tuna fisheries, makes it all the more 

 imperative that the central Pacific skipjack tuna resource be brought 

 into production. 



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