160 Conservation Department 



whicli, as mentioned above, leave slieltered conditions as they be- 

 come larger. It is evident that this is the case in the upper 

 Niagara river from analj^sis of the results of seining there during 

 July. This area was then extremely rich in young fish but there 

 were very few large ones. In the case of the yellow perch, 

 abundant here, young were thickly distributed in weed beds and 

 yearling specimens were common, but large size perch were very 

 scarce. Apparentl}^ the}^ seek deeper Avater as they get larger, in 

 this case doubtless migrating to Lake Erie. The movements of fish 

 within Lake Erie are of considerable concern to the commercial 

 fishery on account of their influence on the availability of certain 

 ones, such as the herring, which may sometimes be taken in largje 

 numbers, and sometimes in scarcely any numbers. ; 



Because of the migratory character of fish, among other reasons, 

 it would be difficult to classify each species according to habitat 

 in the lake. It is worthy of note, however, that comparatively few 

 species are taken in the very deep water, Avhere summer tempera- 

 tures are cold. Herring, blue pike, Avhitefish, ling, lake trout, perch, 

 sculpins and trout-perch are practically all of the fishes found 

 there. The vast majority of species are limited to more shallow 

 water. Some, as the perch and blue pike, range over both types 

 of habitat. 



Factors Contributing Toward a Decline of Fish Numbers. — 



The finny tribe seems to be on the decline wherever civilization 

 has brought its influence. Some of the factors that are concerned 

 in the present case are : 



(1) Clearing of the forests: This has resulted in a great many 

 streams becoming too warm for trout, and others becoming entirely 

 dry^ in the hot season. Stream conditions must influence lake con- 

 ditions, particularly in regard to those fish which spawn in streams. 



(2) Pollution: The pollution of streams must act to reduce the 

 number of fish resident in them and also to reduce the number of 

 lake fish that use streams as spawning areas. Many areas, other- 

 wise suitable for spawning and rearing young, are ruined for 

 these purposes by pollution. Lower Buffalo creek is obviously 

 unfit for eggs or young of fish, and seemed to contain no form 

 of fish life. (The oxygen test at its mouth was zero.-) Buffalo 

 harbor had few young fish when collections were made there. 

 Although almost all water that was seined yielded at least a few 

 fish of one sort or another, conditions in parts of Smoke, Catta- 

 raugus, Canadaway, Silver and other creeks, and in the Niagara 

 river did not appear to be optimum conditions for adult fish to 

 find their natural food and to spawn, or for the young to thrive. 

 As mentioned in a previous report,"* the mere fact that a polluted 

 area of water Avill not kill fish placed there as a ' 'minnow test'^ 



1 Rafter, G. W. The Hydrology of the State of New York. N. Y. State Museum 

 Bull. 85, 1905. J 



2 See page 129. 

 * Oswego survey, 1927, p. 92. 



