BioLOGiCAi. Survey — Erie-Xiagara Watershed 163 



present conditions, certain selected species are fished, thus remov- 

 ing large numbers of them from competition and making a larger 

 per cent of the food available to the species that are not fished. 

 This places these in a position favoring their increase to such a 

 point that they will consume, in all probability, so large a per 

 cent of the available food as to constitute a check to further in- 

 crease of species requiring the same type of food. Although the 

 last statement is of a theoretical nature, there is much evidence 

 to support it. Take for example, trout streams that are so heavilj^ 

 fished as to greatly reduce the numbers of trout. ]\IinnoAvs, and 

 perhaps others, will become very numerous, so numerous as to 

 make it difficult for trout to increase fast in the face of this food 

 competition. It is quite true that Lake Erie is rich in food, 

 especially in plankton, and the fish there appear to grow fast. 

 Many are indeed fat. But, young of certain of these same species 

 are concentrated in relatively small areas where there is shelter, 

 and must stand heavy competition from other young fish and also 

 from adult fish of those species which inhabit similar situations 

 and feed upon similar food. 



Suggestions and Recommendations. — As a result of a brief 

 study, covering only three months, extensive recommendation can- 

 not be proposed. The following suggestions are made : 



(1) If it is proved by analysis of full statistics of catches that a 

 desirable species is decreasing, with or without artificial propaga- 

 tion, give this species protection during the spawning season. 



(2) Such areas as are proved to be spawning grounds of fish 

 or rearing areas for young fish should be kept free from pollution. 



(3) All conservation measures as to fishing seasons, size limits, 

 method of capture and the like should be based on careful study 

 and should be adopted for the entire area by joint action. 



