FISHERY BULLETIN: VOL. 70, NO. 3 



than 0.00 in 1969. Some positive index values 

 of less than 0.005 will be recorded as 0.00. 



QOO 



1963 



1964 



1965 



1966 



1967 



1968 



1969 



Figure 4. — Total catch and average index value for the 

 Pacific sardine. 



night; therefore, the night index should be the 

 best measure of apparent abundance. The night 

 index declined from 2.98 in 1963 to 1.36 in 1965; 

 however, the index level showed an increase in 

 1968 to 2.25 and a sharp decline in 1969 to 0.65. 



300 



2O0 



1.00 



0.00 



1963 



1964 



1965 



1966 



1967 



1968 



1969 



Pacific mackerel (Figure 5) — Data show that 

 Pacific mackerel are observed in greater fre- 

 quency and abundance during the night; there- 

 fore, the night index should be a better indi- 

 cator of apparent abundance. The night index 

 declined sharply from 0.91 in 1963 to 0.14 in 

 1966 and continued the decline to less than 0.00 

 in 1969. 



20 



z 

 o 



I 10 

 u 



I- 

 < 

 o 



_J 

 < 



fe 5 



PACIFIC MACKEREL 



INDEX 



DAY 



NIGHT 

 TOTAL CATCH 



v_... 



00 



050; 



1963 



1964 



1965 



1966 



1967 



1968 



■—'000 

 1969 



Figure 5. — Total catch, average index values for the 

 Pacific mackerel. 



Jack mackerel (Figure 6) — Observation of 

 data show that jack mackerel is sighted more 

 frequently and in greater abundance during the 



Figure 6. — Total catch and average index values for the 

 jack mackerel. 



Pacific honito (Figure 7) — Bonito are ob- 

 served in greater frequency and abundance dur- 

 ing the day; therefore, the day index better 

 represents any changes in apparent abundance. 

 The day index showed only a slight decline dur- 

 ing the 1963-1967 period, declining from 1.62 to 

 1.34. However, since 1967 the index has de- 

 clined rapidly to a low in 1969 of 0.18. 



300 



2 50 



2.00. 



> 

 ui 



1.50 



z 



00 



0.50 



000 



1963 



1964 



1965 



1966 



1967 



1968 



1969 



Figure 7. — Total catch and average index values for the 

 Pacific bonito. 



1016 



