FISHES AND MANKIND 403 



science to give a definite opinion on the all-important question 

 as to whether or no modern intensive fishery operations are 

 affecting the composition of the stock of edible fish in the sea. 

 Speaking generally, however, it may be said that, as far as the 

 pelagic species are concerned, fears of over-fishing are ground- 

 less, and that the stocks of such fishes as the Herring may 

 actually be increasing. The case of some of the demersal fishes, 

 inhabiting comparatively restricted areas of fairly shallow water, 

 presents a different problem, and it may be that in places 

 like the North Sea a greater weight of fish is being removed 

 each year than can be fully replaced by the natural processes 

 of reproduction and growth. It must be borne in mind that 

 the area of the North Sea is little more than 130,000 square 

 miles, and that more than one million tons of fish are taken 

 from it every year. Further, the area covered by the nets of 

 British trawlers alone has been estimated at about 1 10,000 square 

 miles, and one authority has pointed out that every square foot 

 of the Plaice grounds of the North Sea is trawled over on the 

 average two or three times every year. 



The Plaice is, of course, one of our most important demersal 

 species, and apprehensions as to the stability of the stocks were 

 first entertained in the latter years of the last century, following 

 the introduction and spread of steam trawling, but the pressure 

 on the home grounds was relieved for a time by the spread of 

 trawling to more distant regions, and the matter did not become 

 acute until recent times. The late war provided a very interest- 

 ing scientific experiment on a large scale, and one which was 

 watched with some interest by scientific investigators. During 

 the period 1914-1918 the North Sea was virtually closed to 

 trawlers, and as a result the Plaice grounds were almost com- 

 pletely rested. Immediately afterwards trawling was resumed, 

 and the catches of Plaice during the first year after the war 

 were very much greater than those recorded in 1913, but 

 included large numbers of old and poorly nourished fish, due 

 to the overcrowding of the grounds. In succeeding years the 

 weight of fish became progressively less and less, and the figure 

 to-day is just about the same as that of 191 3. At the same 

 time, however, the average size of the fish is distinctly smaller 

 than in the year immediately after the war, suggesting that 

 the fish are being caught before they have a chance to grow 

 to a reasonable size. It would seem, therefore, that there are 

 some grounds for alarm as far as the Plaice of the North Sea 

 are concerned, but in \'iew of the legislative measures that 



