Biological Survey — Oswego Watershed 91 



cornutus frontalis), seulpins {Coitus cognatus and less often 

 Coitus bairdii bairdii) , common sucker, fan-tailed darter, pearl 

 minnow (both subspecies), fallfish, red-sided dace, cut-lips min- 

 now, hog sucker, brook stickleback, tesselated darter, black -nosed 

 shiner, long-nosed dace, black-sided darter, and chain pickerel. 

 In no one individual stream were all of these species found. 



Vermin Fishes. — Certain fish are themselves of little value as 

 food and are known to eat the more useful kinds. Examples of 

 this type are the gar and dogfish. These fish are usually de- 

 stroyed by fishermen when they are taken, much as hawks and 

 crows are often destroyed by hunters. Although a certain amount 

 of control of the destructive species may be desirable, it is not wise 

 to wholly condemn any species without exact knowledge. 



There is much inter-dependence as well as much conflict among 

 aquatic life. We do not well understand the full role played by the 

 various participant species. I have seen golden shiners in the 

 stomachs of large-mouthed black bass and yet seen this same species 

 of minnow eating bass eggs on a temporarily deserted nest. Many 

 of the small fish will eat fish spawn yet if we were to declare 

 them enemies of game fish and destroy them we would curtail 

 one of their chief supplies. At the same time it is quite 

 possible that an overabundance of certain of these small 

 fishes might be greatly detrimental to those game fish whose 

 spawn they might destroy. In such a case it is entirely possible 

 that predacious forms such as the gar and dogfish might perform 

 a useful function by keeping down the numbers of small ones. 



Fishes in Regard to Pollution. — Efforts were made to corre- 

 late data on the occurrence of fishes with the pollution studies 

 made by Messrs. Wagner, Claassen and Cutler and to this effect 

 seining was done in many polluted streams, Although it was 

 impossible to collect thoroughly in all contaminated waters, con- 

 siderable attention was given to typical instances. 



In certain seriously polluted waters fish were found to be 

 entirely lacking. This condition is illustrated by Skaneateles 

 outlet from Skaneateles to Jordan. The main reason for the 

 absence of fish is probably the low oxygen content of the water 

 at certain times (see Mr. Wagner's report, p. 114). 



Several streams of the region, polluted to a less degree, were 

 found to contain fish in considerable numbers. In these in- 

 stances, however, it was interesting to note that the fish fauna 

 was distinctly different from that of unpolluted streams nearby 

 or even from that of the same stream in its clean parts. Canan- 

 daigua outlet furnishes an illustration of such an upsetting of the 

 natural fish population caused by pollution. This stream receives 

 treated sewage and some manufacturing wastes from the city 

 of Canandaigua. At no place was the oxygen found to be danger- 

 ously low, but at a point a few miles below the city, organisms 

 indicative of pollution were common, namely, tubifex worms, 

 various snails and leeches. The normal clean-water types of in- 

 sects and other invertebrate life were absent. Here a collection 



