FISHERY BULLETIN: VOL. 75, NO. 4 



29 



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 Q. 



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1962 



FIGURE 8. — Christmas Island temperature, 1962-67: A. Long-term variation produced by 12-mo moving average and by 

 harmonic function (n = 1-19). B. Short-term variation (monthly input values minus long-term values). Solid line — 12-mo moving 

 average; dashed line — harmonic function (n = 1-19). 



every second year. After harmonic analysis and 

 separating the hypothetical curve into a long- 

 term and a short-term variation, the latter would 

 exhibit an annual periodicity during every year. 

 Thus, the mathematical procedure cannot an- 

 swer the questions posed above. The procedures 

 illustrated in Figures 7 and 8 as well as other 

 procedures, separate the scales of variability but 

 there is no basis for inferring that the long-term 

 changes are related with, possibly, ocean-wide 

 processes and short-term changes with local proc- 

 esses. Only if the local processes are measured 

 is there a physical basis for the separation into 

 different scales of change. 



Speculations About Temperature 

 and Salinity Variations 



It is not the purpose of this paper, and the infor- 

 mation is not available, to investigate the causes 

 for the temperature and salinity variations that 

 have been described. Nevertheless, such an inves- 

 tigation would further an understanding of the 

 fishery environment as well as the ocean-atmo- 

 sphere linkages. It is useful, therefore, to specu- 

 late about the processes affecting changes in 

 surface properties. 



In Hawaiian waters air-sea interaction pro- 

 cesses and advection appear to dominate the local 



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