FISHERY RESEARCH 335 



tions have been wiped out ; several species of whales have 

 come dangerously near complete extermination and what 

 were once nourishing whale fisheries practically no longer 

 exist. And it seems certain that sooner or later there 

 will be even a risk of depleting the stock of certain fish. 

 It has been mentioned previously that the plaice, for 

 instance, appear to be being fished out of the North Sea to 

 a dangerous extent. 



What might be regarded as one of the largest experiments 

 ever carried out was a direct result of the great war. For 

 five years the North Sea was virtually closed to the steam 

 trawlers ; anyone who went out to fish did so at his own 

 risk. Consequently it can be said that the great plaice 

 grounds of the North Sea were almost completely rested. 

 This afforded a real opportunity to see whether man's 

 efforts as a fisherman could actually have any effect on the 

 stock of fish present in so vast an area of water. 



The statistics of the landings of plaice at the big fishing 

 ports in the years right up to the beginning of the war were 

 known. The landings in the years immediately following 

 the end of the five years' rest brought about by the war 

 were watched with the very greatest interest. Would the 

 catches be still exactly the same as in the years before the 

 war, or would the stock of plaice have become recuperated 

 and so afford undeniable evidence of the effects of fishing ? 

 The findings were instructive indeed. 



In the first year after the war the catches were very much 

 greater than in the years before the war. The catches were 

 also characterized by the presence of very great numbers 

 of old, poorly nourished fish, the grounds being over- 

 crowded. But in the succeeding years the numbers of 

 plaice caught became less and less until now we are once 

 more down to, or even below, pre-war figures. The average 

 size of the fish too is much smaller than that of those caught 



