50 



TbE IMPOVERISHMENT OF THE SEA. 



estimating the increase in the total catches as from 33 per cent, to 

 50 per cent, the catch of round fishes alone having been even doubled. 



The relative efficiency of the otter and beam trawls as worked by- 

 steamers can be measured, however, in a reliable manner without 

 recourse to personal opinions. It liappens that the trawlers landing 

 fish on the East Coast of Scotland have been exclusively steamers for 

 some years past, and the aggregate catches of these boats, together with 

 the number of vessels at work, are given in the Annual Eeports of the 

 Scottish Fishery Board. There are usually about a hundred steam 

 trawlers working annually from Aberdeen and other East Coast ports. 

 The otter trawl having been introduced at Granton in 1894, and rapidly 

 adopted by steam trawlers in general during the course of 1895, the 

 changes wrought by its adoption can be clearly determined by com- 

 paring the average catch per trawler for a year or two prior to 1895 

 with the average catch per trawler for the years immediately following 

 1895, the year of transition being of course omitted. 



Table XI., shoiving the Total Catches of Scottish Steam Trawlers for two 

 years hefore and after the introduction of the Otter Traivl in 1895. 



Aggregate Catch (cwts.). 



Table XI I., showing the Average Annual Catches jjer Boat (cwts.) of 

 Scottish Steam Trawlers, 1893 to 1897, and the Relative Efficiency of 

 the Otter and Beam Trawls deduced therefrom. 



Relative efficiency of Otter 2-12 ISo 095 MO 137 



The results of a comparison on these lines are set forth in Tables XI. 



and XII. 



It will be seen that the aggregate total catches in 1893 and 



