Most, if not all, previous studies based on 

 the Japanese longline data — e.g., Koto (1969); 

 Mather, Jones, and Beardsley (1972); Saka- 

 moto (1967) — have tacitly assumed that all 

 observations are of equal value in delimiting 

 distribution and abundance of the species 

 taken by the fishery. The assumption probably 

 is not correct because of the grossly unequal 

 amounts of fishing in different parts of the 

 Atlantic. For example, there were a total of 

 some 7 million hooks fished in 1956-68 in 

 each of the two most heavily fished 5° x 5° 

 squares, vs. a total of only about a thousand 

 hooks fished in the most lightly fished square 

 in the course of the 13 years, a difference of 

 nearly four orders of magnitude. 



For this reason, we show the relative 

 amounts of fishing in Figure 3. The shaded 

 areas include 99% of the fishing effort in each 

 quarter during 1956-68. Within the shaded 

 area the darkest portion includes squares 

 which total cumulatively 75% of the effort; 



the intermediate shading plus the darkest 

 portion includes 95% of the effort. Table 4 

 shows the range of the percentages. The total 

 fishing effort was approximately equal in 

 each of the four quarters — first quarter 120.5 

 million hooks, second quarter 131.6 million 

 hooks, third quarter 120.7 million hooks, 

 fourth quarter 109.0 million hooks. 



Thus, all of the squares outside of the shaded 

 areas in any quarter taken together include 

 no more than 1% of the fishing effort for that 

 quarter, and no one unshaded square in- 

 cludes more than about 0.05% of the fishing 

 for that quarter — at the maximum about 

 5,000 hooks total in 13 years (131.6 million 

 hooks X 0.05% /13). Most of the squares out- 

 side the shaded area include less than 0.05% 

 of the fishing; the average is less than 0.02%, 

 or less than 2,000 hooks total in 13 years. 



A recent publication by Shiohama (1971) 

 shows graphically the distribution of Japanese 

 longline fishing effort for each year in the 

 1956-68 period. 



Table 4 .--Distribution of percentages of fishing effort for each quarter. 



Effort 

 level 



First quarter Second quarter 



Range Number Range Number 



of % of of % of 



squares squares 



Third quarter Fourth quarter 



Range Number Range Number 



of % of of % of 



squares squares 



75% 



95% 



99% 



5.894- 



34 



5.075 



0.924 





0.766 



5.894 



78 



5.075 



0.176 





0.225 



5.894- 



115 



5.075 



0.055 





0.046 



48 



88 



124 



5.169- 



44 



4.070 



0.814 





0.584 



5.169- 



101 



4.070 



0.163 





0.208 



5.169- 



141 



4.070' 



0.049 





0.048 



55 



109 



144 



100% 



176 



193 



203 



200 



Note: The number of squares shown for each effort level is cumulative--!. e . , in the 

 first quarter 95% of the fishing is included in the 34 squares which include 

 75% of the fishing, plus 44 others, or 78 squares. 



