-11- 



Experiment 2 (Figures 5 to 8) , spawning stress mortality compensated at 

 different fishing intensities; growth is not compensated. 



The lowering of spawning stress mortality with increased fishing causes 

 considerable compensation in biomass losses (compare F igures I to ^ with Figures 

 5 to 8) . There is less spread of resulting biomasses with time at high and low 

 fishing levels than in the uncompensated experiment (Experiment 1). This is due 

 to increased compensation at more intense levels of fishing (i.e., the spawning 

 stress mortality decreases at a higher rate than the increase of fishing mortality). 

 The biomass changes in Figures 7 and 8 are smaller than those in Figures 5 and 6. 

 This is due to lower fishing mortality in Figures 7 and 8. 



Experiment 3 (Figures 9 to 12), growth is compensated for effects of fishing; 

 spawning stress mortality is not compensated. 



The effects of fishing on growth produce quantitatively similar results on 

 biomass dynamics to those caused by spawning stress changes (compare Figures 5 

 and 6 with 9 and 10), except in the case of density dependent fishing only 

 (Figures 11 and 12) where the resulting biomasses are slightly higher. (At very 

 high levels of fishing, (e.g., F greater than 0.3) this increase of biomass might 

 not occur . ) 



Experiment h (Figures 13 to 16), both biomass growth and spawning stress 

 mortality are affected by fishing. 



The biomass changes are heavily compensated - both biomasses increase with 

 time and this increase is greater at the higher levels of fishing used in this 

 experiment. The spreading of biomasses between low and high fishing is less in 

 pollock that in yellowfin (Figures 13 and 14). (More biomass removed in pollock, 

 thus higher compensation.) In case of density dependent fishing only (Figures 15 

 and 16), the increase of biomass is less than in Figures 13 and ]h . This difference 

 is due to less fishing and less compensation of biomass in Figures 15 and 16. 



