190 



MAKING A FISHERY. 



Habitat of 

 large trout in 

 hot weather. 



Tendency to 

 work into 

 carriers for 

 Mayfly. 



smolt, it would in the end tend to increase the 

 stock of salmon in a river. 



As the season progresses, and the weather 

 becomes warm, the larger trout are more and 

 more inclined to keep in the deep water during 

 the daytime, coming on to the shallows at dusk 

 to feed on the minnows, crustacean, molluscae, 

 winged flies and their larvae. Probably this 

 desire for deep water is in obedience to the 

 instinct for seeking shelter from the heat of the 

 sun. Whether the fish are in the weeds, which 

 are usually of more luxuriant growth in deep 

 water than shallow, whether they lie close to 

 the bank in the shade, or whether they merely 

 keep close to the bed of the river, they are 

 more or less able to obtain the desired shelter. 



In many rivers the Mayfly is more plentiful 

 in carriers and tributaries than in the main 

 stream. Any reason advanced to account for 

 this must at least be the result of conjecture ; 

 but I am inclined to think that the Mayfly 

 larva, although its habitat is in mud of a 

 particular sort, does not flourish in, but, on the 

 contrary, avoids, portions of a river where the 

 bed is that black fetid mud, which is the result 

 of decomposition of vegetable matter, sewage, 

 and other pollution. If this theory is accurate 

 an additional incentive is provided to impel 

 owners and lessees of fisheries to try and pre- 



