THE IMPOVEKISHMENT OF THE SEA. 



21 



enabling a greater stock of these fish to live on the same extent of 

 ground. Moreover, from their smaller size, there is reason to believe 

 that the numerical increase in dabs would be greater than the numerical 

 decrease of the plaice and lemon soles which they may be held to have 

 supplanted. This explanation derives support from the reported in- 

 crease of dabs in the open, as well as the closed waters of the regions 

 investigated. 



It is, however, sufficient for my present purpose if I have demon- 

 strated that changes have taken place in the abundance of fish in 

 Scottish waters, which are attributable in all probability to the effect 

 of man's operations ; the decrease of plaice and lemon soles to the 

 reduced supply of fry caused by the excessive destruction of these 

 species by over-fishing in the offshore waters, the increase of dabs and 

 long rough dabs either directly to the protection of their spawning 

 grounds, or indirectly to the natural consequences, in the struggle for 

 existence, of the reduction in the numbers of their competitors. 



THE STATISTICAL EVIDENCE. 



I. Annual Catches of Grimsby Sailing Trawlers, 1860-92. 



Two Grimsby smack-owners have submitted statements concerning 

 the annual catches of their vessels during the last forty years. 



At the request of the Sea Fisheries Commission of 1863, Mr. Henry 

 Knott provided a statement of the weight and value of fish caught by 

 an average Grimsby trawler during the years 1860 to 1864, which is 

 printed as an appendix to the report of the Commissioners (p. 46), 

 and is quoted in Holdsworth's Deep -Sea Fishing, 1874, p. 88. The 

 original statement gives the weight in tons, hundredweights, and 

 quarters, and the value in pounds, shillings, and pence. I give below 

 a copy of this statement, omitting unnecessary details, and adding 

 an average of the five years' records. 



Table III., showing the Weight and Value of Fish caught hy one 



Grimsly Travjler during the years 1860 to 1864. 



(From a Return submitted by Mr. Knott to the Sea Fisheries Commission in 1865). 



