FISHERMEN AND FISHERIES. 167 



application of these contrivances to river navigation, and 

 many streams which had hitherto been free from obstruc- 

 tions of this kind were invaded. The navigation interest, 

 which had hitherto demanded the removal of fishing weirs, 

 and which had thus been such a powerful ally of the fishing 

 interests, now encouraged the construction of still more 

 serious obstacles to the ascent of fish. But this was not all. 

 Not merely did the new locks present almost insuperable 

 obstructions to the ascending salmon, but they changed the 

 character of many rivers, transforming their natural reaches 

 of rapid running water into a succession of comparatively 

 stagnant pools. Thus was laid the foundation of the real 

 scarcity of salmon which, first experienced towards the end 

 of the last century, was more and more severely felt as the 

 nineteenth century grew old. The frequent abstraction 

 of water from the rivers for the purpose of feeding the Neglect of 



fisheries by 



numerous canals, into the construction of which the whole other 



r i - ... industries. 



energies of the country were thrown, was another incident 

 in the revival of navigation interests which added still 

 further to the difficulties of the salmon. The growing 

 manufacturing activity of the country,* with the consequent 

 pollution of the rivers, was a fresh source of mischief. In 

 1804, and again in 1818, legislative notice of this was taken 

 in an Act forbidding, among other things, the pouring into 

 rivers of water " in which any green lint or flax has been 

 steeped, or any water impregnated with any material or 

 drug pernicious to fish : " but the manufacturing industries 

 soon outran this modest enactment, while the introduction 

 of deep drainage for agricultural purposes, and of systems 

 of town sewerage, still further tended to complete the 



* In 1804 an Act regulating the Solway fisheries, specially exempted 

 weirs built in connection with iron forges from the prohibition against 

 dams in salmon rivers. 



