FISHERY BULLETIN: VOL. 74, NO. 1 



Table 6. — Total landings in metric tons (MT) of skipjack tuna in Hawaii, catch per stan- 

 dard day fished, relative fishing intensity, catch per standard effective trip, and relative 

 effective fishing intensity, 1948-70. 



z 

 o 



2 t- 



o £ 



to Q. 



in Q 



=) ir 



X 



o 



O o 



2 2 



u> 



-^ — I — I — I — i — I — 1 — I — I — 1 — I — \ — r 



TOTAL CATCH 



CATCH/STANDARD DAY FISHED 



RELATIVE FISHING INTENSITY 



28 



2 6 



10 

 Q. 



(O 



to 



< 



24 



CO 



o 



z 

 < 

 <o 



z> 

 o 



22 f 

 W 



z 



I- 

 z 



-20 



I 8 



16 



J I 1 1 L. 



1950 



1955 



I960 

 YEAR 



1965 



1970 



o 



z 

 I 



(O 



UJ 



> 



< 



UJ 



Figure 6. — Total catch, catch per standard day fished, and the 

 relative fishing intensity for skipjack tuna in Hawaii, 1948-70. 



in the environment, and to the strength of the 

 year classes. 



Catch per standard effective trip {CI SET) and 

 relative effective fishing intensity, the two indi- 

 ces used in previous studies (Uchida 1966, 1967, 

 1970), are also given in Table 6. As expected, both 

 CISDF and CISET fluctuated similarly in 1948- 

 70 (r = 0.998; df = 21; P<0.01). Likewise the 



correlation between relative fishing intensity and 

 relative effective fishing intensity was sig- 

 nificant, indicating that changes in one paral- 

 leled changes in the other (r = 0.982; df = 21; 

 P<0.01). It can be concluded that although the 

 use of effective trips in previous studies produced 

 biased results, which deviated from more precise 

 estimates calculated from days fished, its use did 



160 



n — \ — \ — \ — I — I — \ — r 



CLASS 2 VESSELS 



_J \ 1 L_ 



1950 1952 1954 1956 1958 I960 1962 1964 1966 1968 1970 

 YEAR 



Figure 7. — Average number of days fished per vessel per year 

 among class 1 and class 2 Hawaiian skipjack tuna vessels, 

 1948-70. 



68 



