Finally, an instantaneous predation coefficient was computed: 



c = Jin (1 - C/B^_^) ik) 



Spawning stress mortality (s) was prescribed from Laevastu (1983). In some 

 runs it is made a function of fishing mortality for the quantitative study of 

 the inverse relations between fishing and spawning stress mortality effects: 



5 = 5- ^^w (5) 



tw 



Pollock, r = 0.0175 



Yel lowf in, r = 0.01 



In the first set of runs (see Section 5) where juvenile recruitment was not 



affected by fishing, the values for r were: pollock 0.6 and yellowfin 0.85. 



In the second set of runs (see Section 6) where the juvenile recruitment was 



affected by fishing and some fishing occurred on not fully recruited year 



classes, the values for r were: pollock 0.^4, yellowfin 0.65. 



Fishing mortality (f ) consists of "constant" catch (F ) and/or different 

 ^ tw c 



stock density dependent fishing (F.) and/or a combination of both. The constant 



catch was converted to fishing mortality coefficient (fc) : 



F = F /B^ ,; fc = £n (l-F) (6) 



c t-1 



The blomass of previous time step (B .) is used for the same reason as in 

 Formula 3 above. 



fd - f (fd' '7) 



%„ ■ 'c ^ fd <8> 



2 



Pollock, F = 32 kg/km , f > = 0, increment 0.006, 



^ ° max. 0.018 



2 

 Yellowfin F = 32 kg/km , f , = , increment 0.003, 



'^ max. 0.009 



