198 THE PRODUCTIVITY OF THE SEA [PART II 



North and Irish Seas ceased to be as profitable as in the middle 

 decades of the century. If all that man could do had been 

 inoperative in reducing the fish population of the North Sea, then 

 this fishing area would have been sufficient. But it was discovered 

 that profitable " voyages " could no longer be made there, and so 

 year by year, since the beginning of the 'nineties, the steam 

 trawlers have forsaken the North and Irish Seas for more 

 lucrative fishing grounds in the Bay of Biscay, off the coasts of 

 Ireland, off Iceland, and lately in the White Sea. 



This is the " practical " argument in favour of the depletion of 

 the North Sea fishing grounds. A complete and rigid demon- 

 stration of the decreased abundance of fish on this ground has 

 apparently still to be made. If we had an absolutely exhaustive 

 system of collection of fishery statistics it would be an easy matter 

 to shew what is the condition of the North Sea relative to its 

 condition fifty years ago. But so imperfect are our fishery 

 statistics that no attempt at such a demonstration of depletion 

 has yet been made that has not been unfavourably criticised. In 

 1900 Garstang^ shewed (1) that the total quantity of certain 

 classes of fish landed from this area had not increased very greatly 

 during the decade 1889-98 ; (2) that the catching power of the 

 vessels employed in fishing there had greatly increased ; and (3) 

 that, as a consequence, the average catch made by each vessel had 

 gradually decreased. Fulton^ had previously adopted the same 

 line of argument with reference to the Scottish trawl fisheries. 

 But it has been contended^ that this method of shewing the 

 depreciation of the fishing grounds is a fallacious one, though I 

 cannot see in what manner the method fails. 



Many attempts, both in Great Britain and on the Continent, 

 have been made to shew that the fishermen catch a very notable 

 percentage of the fish present on the grounds. Numbers of 

 living plaice have been marked by means of various kinds of 

 labels, and these fishes have been liberated in the sea. After a 

 year has elapsed a certain percentage of these marked plaice are 

 always recaptured by the fishermen, and it is claimed that the 



1 Journ. Mar. Biol. Association, vol. vi. 1900-3. 



- Ann. Kept. Scottish Fishery Board for 1891, Pt. 3, p. 171. 



2 Ann. Rept. Inspectors of Fisheries for England and Wales for 1900, p. 5. 



