Prince. — Irrigation Canals and Fisheries. 161 



had resulted. In the Grand River in Ontario a dam was erected 



near Dunnville. Owing to complaints that fish could not migrate 

 up the river, and that the dam obstructed ascending schools, a 

 fishway was erected ; but proved wholly useless. Fish, however, 

 above the dam began to increase, and angling greatly improved, 

 for such species as black bass and pike perch spawned, and 

 the schools of young were retained and could not leave the river ; 

 hence the fishing was in every way benefited. The local anglers 

 appreciated the situation, and adopted a system of netting bass 

 and other fish below the dam and transferring them to the 

 deeper waters above, where they permanently remained. Now, 

 the canal and reservoirs which form so important a part of all 

 schemes of irrigation provide the very conditions for similar fish 

 culture work. As a rule the lakes and streams in northern areas, 

 where irrigation systems are being carried out, are shallow, often 

 not very pure, frequently affected by saline and alkaline ele- 

 ments, reduced or dried up in summer, and frozen to the bottom 

 in winter, and thus afford every condition unfavorable for fish. 

 A wholly new condition is created by the construction of canals 

 and reservoirs under irrigation schemes. Large bodies of water, 

 deep, cool, and free from excesssive impurities are created, and a 

 great opportunity arises, therefore, for turning them to account 

 as fish-producing constructions. Irrigation canals might become 

 angling reserves, or, if of larger dimensions, sources of fish food 

 for the communities in which they are located. 



What then are the possibilities of securing fish production 

 in such larger reservoirs or canals? Insect food usually estab- 

 lishes itself in a very short time, often in a few months after 

 water is admitted; various fresh-water moUusks, water snails, 

 etc., are carried by birds, and rapidly become numerous. But the 

 food conditions necessary for fish could be hastened by the trans- 

 ference of such aquatic life from other waters. Species of small 

 minnows (always excluding the destructive and harmful stickle- 

 backs, small fish with three or more sharp spines on their back) 

 will require to be introduced in most cases, as there are few 

 large kinds of fish which do not prey upon these small species 

 or feed upon their spawn and diminutive fry. But the question 

 of food for fishes need cause no concern as both minnows and 

 insect food and water snails will rapidly increase soon after 

 they are introduced. It must, I fear, be taken for granted that 



