THE FISHES OF GEORGIAN BAY 7 



S»^SSIONAL PAPER No. 39b • 



green bass, perch, and catfish, in other words those species which are more or less 

 characteristic of ordinary swamps. Such lakes, however, will not be likely to con- 

 tain pike, and will not contain small-mouthed bass or pickerel. Moreover those 

 species characteristic of the smaller inland ponds will be present only in the more 

 confined situations, and will likely be in the minority. Undoubtedly food supply 

 has something to do with these differences, but it is evident from a consideration 

 of the facts that food supply is not one of the important factors. Apart from the 

 general questions of distribution, the matter is of some practical importance, since 

 it involves the question of the habitability of certain smaller lakes to small mouthed 

 bass or other game fishes and the reservation of such lakes for stocking purposes. 

 Sand beaches, channels, or similar clean surfaces, tend to be occupied by live 

 species, all of which, however, are also found in the more open swamps. These are 

 the small perch-like forms known as log-perches and darters (Percina caprodes, 

 Boleosoma nigrum, Etheostoma iowae), the silverside (Labidesthes sicculus), and the 

 common garpike {Lepisosteus osseus). The maskinonge {Lucius masquinongy) , 

 an important game fish, and the largest of all the inshore predaceous species, may 

 also be included in this category, since it shows a preference for sand banks or sandy 

 river channels. 



The food supply of swamp areas and sand beaches, like that of the deep 

 water, is of three orders, namely, (a) plankton, or microscopic organisms living 

 on the bottom; (b) bottom organisms of a higher order, such as crustaceans, 

 molluscs, and insects, or surface insects; and (c) smaller fishes. The smallest 

 species and the young of all species are obliged to feed upon minute or microscopic 

 organisms. Fishes of intermediate adult size, and also the young of large fishes 

 at a certain period of growth, depend on crustaceans, molluscs, and insects. They 

 show on the whole a preference for insect diet, and augment the natural supply 

 of aquatic insects by feeding upon terrestrial insects which fall into the water. 

 Finally, all the smaller species and the young of all larger fishes not naturally 

 protected form a general food supply for the largei predatory types. Theie are 

 no shore fishes of larger dimensions which retain the plankton feeding habit after 

 the manner of the lake herrings in deep water. 



On the whole the shallow water zone in this region does not appear to favor 

 either the presence of a large number of species or the attainment of large size. 

 The majoiity of species in which the normal adult size is not great appear to be 

 smaller in this region than elsewhere. They may be dwarfed by some combination 

 of environmental conditions, but the indications are that they have fewer chances 

 of reaching the noimal size. The number of intermediate and larger fishes of 

 more or less predatory habit is eight, and the destruction wrought by these on 

 smaller species must be enormous. The smaller species themselves have to depend 

 for shelter on weeds, rocks, or shallows, and possibly the fact that the water is 

 at all times transparent tends to turn the balance in favor of their natural enemies. 

 Certain conditions of environment which in other situations, especially in 

 sedimentary areas, may confer advantages on certain species are here unrepre- 

 sented. For example, with the exception of the silver lamprey, a parasitic form 

 which up to the present has only been taken on fishes temporarily inhabiting 



