280 



Mr. W. H. Pearsall. 



account of the Lake District fisheries is based on that of "Watson,* supple- 

 mented and modified by the opinions of local fishermen and a long personal 

 acquaintance with the fishing on some of these lakes. 



Fish are undoubtedly most abundant in the more evolved lakes and least 

 so in the primitive ones ; but this condition is due almost entirely to the 

 numbers of coarse fish, perch {Perca Jluviatilis), and pike {Esox Iv.cius), which 

 are especially abundant in Ullswater, Windermere, and Esthwaite, where they 

 are increasing rapidly. The fish of the primitive lakes is undoubtedly the 

 trout {Salvia fario), of which the largest numbers of well-grown fish probably 

 occur in Crummock, Derwentwater, and Hawes Water. Pike and perch are 

 absent from Wastwater, though the former were introduced some years ago 

 without success. There are said to be a few perch in Ennerdale, but trout 

 are the only abundant fish. On the other hand, trout are apparently 

 decreasing rapidly in numbers in Ullswater and Windermere, and are practi- 

 cally extinct in Esthwaite. Char (Salmo Willuglibii) occur in the deeper 

 primitive lakes, and professional char-fishers say they also are decreasing in 

 Windermere, as is known to be the case in Ullswater. Eels {Anguilla vulgaris) 

 and minnows (Zmciscus plioxinus) are present in all the evolved lakes, and 

 perhaps in Wastwater and Ennerdale also. It is certain, however, that there 

 is a general progression in the lake series from the trout community to the 

 perch-pike community, and the succession of these animal communities, 

 therefore, closely parallels the development of the lake and its vegetation, as 

 follows : — 



Trout. Perch— Pike. 



Primitive lakes. Evolved lakes. 



The economic value of fisheries may be assumed, roughly, to depend on 

 two factors, the quantity of fish present, and their value from a commercial 

 aspect, chiefly as food. From the former point of view, lakes like Windermere, 

 Ullswater and Esthwaite rank first, since they undoubtedly contain the 

 greatest numbers of fish per unit area. But, in food value, trout are the 

 most important of the lake species, and, in this respect, the more primitive 

 and intermediate lakes represent the more valuable fisheries, notably 

 Derwentwater, Crummock and Hawes Water. 



An increase in the abundance of fish is normally correlated with an 

 increase in the abundance of plankton organisms, the phytoplankton 

 forming the ultimate source of this increase. This correlation is so well 

 established that we may regard the increase of fish in the more evolved 

 lakes as being due to the physico-chemical conditions, which induce a more 



* ' The Lake District Fisheries/ London, 1898. 



