and the longitudinal standard deviations exhibit 

 relative or absolute minima during the peak 

 periods. The correlation coefficient for effort 

 is similar to the latitudinal moment in that it 

 tends to be near a maximum at the beginning of 

 a peak period and then declines throughout the 

 peak period. 



The longer term trends in effort are shown 

 in figure 11. The longitudinal moment tends to 

 move toward the east, on the average, 0.42 de- 

 gree (about 25 miles or 46 km.) per year. The 

 latitudinal moment tends to move toward the 

 south. 0.52 degree (about 31 miles or 57 km.) 

 per year. The longitudinal standard deviation 

 tends to increase 0.75 degree (about 45 miles 



or 83 km.) per year whereas the latitudinal 

 standard deviation increases at the lesser rate 

 of 0.27 degree (about 16 miles or 30 km.) per 

 year. The correlation coefficient decreases, 

 on the average, from a value of near to nearly 

 -0.4 over the 13-year period. 



Catch and catch-per-unit-of-effort .--The spa- 

 tial statistics for catch and CPUE are, in gen- 

 eral, similar and therefore do not warrant sep- 

 arate discussion. 



Again referring to table 3 and to figures 9 

 and 10. we see that the maximum longitudinal 

 moments for catch and CPUE are centered on 

 the third quarter of the year whereas the most 

 typical time for the minimal value for the lon- 



St 



o 



s 



< 



> 



z 



10 



5 







-5 



-10 



Figure 9. --Spatial statistics for catch ig'tS-fel on the North Pacific albacore 

 longline grounds. The heavy ] i ne represents the peak fishing period from 

 December to March. 



\Z 



