since both species are largely competitors for the same foodo In 

 that case it is possible that a satisfactory protection of the 

 plaices will decrease the density of the soleo This would be an 

 argTjment to include the sole in the protection scheme,, A stronger 

 argviment is raised, if an infraction of the 8 centimeter minimum 

 mesh-width regulation is to be prevented, a size will have to be 

 set for the sole to correspond with this mesh width. This is 

 probably 25 centimeters; although exact data of the selectivity of 

 the 8 centimeter net for sole are not available. There can be very 

 few objections against this size. Shortly before the last war 

 large quantities of small sole were landed. During 1938 the smallest 

 group varied between 15 to 27 centimeters with an average of 21 

 centimeters. However, it is very uneconomical to land such small 

 sole. More than any other species the sole brings in a considerably 

 higher return if left to grow for a few years. 



The sol© has a high rate of growth, higher than that for plaice. 

 It appears that up to now this rate of growth is not inversely 

 proportional to the density of the stock. 



Probably due to a very efficient method of finding food, 

 the sole still manages to get a sufficient amount of food for a 

 maximum growth speed, even at the density it has now reached. 

 The natural mortality is low and is fully compensated for by 

 the growth. Ifhile the plaice suffers a disadvantage by the 

 migration of older fish from the coast, thereby getting outside 

 the reach of the fishermen who have protected it at a younger age, 

 the older sole return in great quantities to the coast to spawn. 

 Moreover, although the small sole has a comparatively high value, 

 the older ones bring a considerably higher price per kilogram. 

 The prices werer 



79 



