FISHERY BULLETIN: VOL. 87, NO. 3, 1989 



3.0 



2.0 



1.0  



2.0 



1.0 



3.0 



2.0 



1.0 







1973 



Po=0.509 

 a=0.057 

 n=52ij 



1977 

 Po=0.159 



a=o.om 



n = 158 



1981 



Po=0.321 

 0=0.049 

 n=131 



1983 



Po=0.329 

 a=0.049 

 n = 568 



Po=2,500 

 a=0.091 



n--9 



1981) 



Po=0.596 

 01=0.058 

 n = 165 



1975 



PO=0.605 

 a=0.081 

 n=331 



1982 



Po=0.579 

 a=0.070 

 n=505 



1985 



Po=0.154 

 "=0.041 

 n=355 



1975 



Po=0.198 

 a=0.114 

 n=57 



Po=1.791 

 a=0.074 

 n=458 



10 20 30 40 50 10 20 30 40 50 10 20 30 40 50 10 20 30 40 50 



AGE IN DAYS 



Figure 5. — Mortality curves of individual spawning years. Po is the Pacific saury larval production at 

 hatching, a is the daily IMR, and n is the number of tow samples. 



(Watanabe et al. 1988), the total catch in a fish- 

 ing season must come from larvae produced in 

 the spawning period of the same year. For ex- 

 ample, the 1973 catch is related to larval produc- 

 tion at hatching and daily IMR of the 1973 

 spawning year (from September 1972 to August 

 1973). 



Larval production at hatching and the daily 

 IMR have fluctuated somewhat concordantly 

 from 1973 to 1986. The Spearman's Rho is 0.704 

 (n = 14, P < 0.05), indicating a positive correla- 

 tion between Pq and IMR among years. The 



exception to this trend was 1976. The production 

 value of 1976 was one of the lowest in 14 years 

 whereas the daily IMR was very high, probably 

 resulting in a minimum catch of < 100,000 t in 

 1976. 



Mesh Retention of Larvae 



The low values of larval production for the 

 first two size classes precluded their use in the 

 estimation of larval mortality. Since the mesh 

 size of the anterior 3.0 m of the net is 2.0 mm, we 



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