tends to decrease, or even, on occasion, to in- 

 crease during the last few months of the peak 

 period. The longitudinal standard deviations 

 exhibit a maximum value while the latitudinal 

 standard deviations tend to exhibit minimal 

 values during the peak period. Thus, during the 

 peak fishing season the catch andCPUE exhibit, 

 simultaneously, a maximum latitudinal con- 

 traction and maximum longitudinal expansion. 

 The correlation coefficients of both catch and 

 CPUE decline throughout the peak periods. 



The longer term trends based on the Feb- 

 ruary index for catch and CPUE are shown in 

 figures 12 and 13. The 1949 intercept for the 

 longitudinal moment of catch is long. 154.9° E., 



and that for CPUE is also long. 154.9° E. Over 

 the 13-year period the catch tends to move 

 toward the west at a faster rate than the CPUE 

 (0.69 degree or about 41 miles or 76 km. per 

 year versus 0.17 degree or about 10 miles or 

 19 km. per year). The intercepts for the lati- 

 tudinal moments are lat. 30.6° N. for catch and 

 lat. 30.8° N. for the CPUE. The CPUE tends 

 to move to the south at a greater rate--0.13 

 degree (about 8 miles or 15 km.) per year-- 

 than the corresponding index for catch, which 

 moves south at only 0.08 degree (about 5 miles 

 or 9 km.) per year. The 1949 intercept for the 

 longitudinal standard deviation of catch is 14.9 

 degrees, whereas that for CPUE is 14.3 degrees. 



Figure 10. --Spatial statistics for CPUE 19')9-6l on the North Pacific albacore 

 longline grounds. The heavy line represents the peak fishing period from 

 December to March. 



\k 



