Table 7. —Number of NMFS area-month strata in which single 
samples were obtained or substituted. 
Number Strata sampled Strata with one sample 
Species - Year of once (including substitutions) 
Strata! Catch (tons) Catch (tons) 
Yellowfin 
1968 
1969 
1970 
197] 
1972 
1973 
1974 
Skipjack 
1968 
1969 
1970 
197] 
1972 
1973 
1974 
u Only strata in which a catch was made are included. 
x 
WwW 
S 
a 80; 
ao ma 
Ot ad Y a SEPTEMBER 
aire 
ao 
= ° 40) 
= 
w 
w 20 
6 r) 
JUNE 
OCTOBER 
NOVEMBER 
ESTIMATED NUMBER OF FISH (x103) 
AUGUST 
3 6400=C 550—i60—s 7N—sBO—is90—st00—sF'0—s 120s 30 40S 150s 60—s—s170—Ss« 180 30 40 50 60 70 80 90 00 110 20 130 40 150 160 170 180 
FORK LENGTH (cm) FORK LENGTH (cm) 
Figure 6.—Estimated length composition of yellowfin tuna by month caught by American seiners in 1970. (Solid line — stratified procedure with 
substituted samples; dashed line—stratified procedure without substituted samples and strata with one sample.) 
10 
