Osburn. — Conditions Detrimental to Bass. 35 



the scale method) of many of our Ohio game fishes and has 

 discovered that it is possible for the large-mouth bass to 

 reach the legal limit of 11 inches without having had oppor- 

 tunity to breed. The elimination of spring fishing would 

 curb this to some extent or the raising of the legal size to 12 

 inches would accomplish the same purpose. In the lakes 

 this is not so important a matter as it is in the streams, where 

 there are fewer fish and less cover and where over-fishing is 

 more likely to occur. 



Over-fishing at any rate, is not so serious as the other 

 checks already discussed, for at least somebody profits by 

 the fish taken for food and by the recreation involved in 

 their capture and it does not hinder restocking, while pol- 

 lution and interference with the water supply present no 

 such mitigating features and make restocking futile. If 

 boards of fish and game were more careful to investigate 

 the waters they restock and refuse to stock waters that 

 are impure or are otherwise tampered with, they might at 

 least arouse the fishing population to the point where they 

 would insist on doing away with these menaces to fish pro- 

 duction. 



Before closing I wish to say just a few words about the 

 checks on the artificial production of young bass in hatch- 

 eries. Here the conditions are made as satisfactory as pos- 

 sible and most of the checks above mentioned are elimina- 

 ted. Pure water is insisted on as a matter of course, but I 

 believe that it is possible to eliminate parasitism to a greater 

 extent. Some preliminary studies which I have made on 

 our hatcheries in Ohio, indicate that it is not good policy to 

 take water for the hatchery from lakes or streams and that 

 springs should be the only source from which water should 

 be drawn. We have both types in Ohio and while the per- 

 centage of hatch is about equal, the investigation of the 

 young bass indicates that parasitism is almost absent in the 

 young fish from spring-fed hatcheries where the ponds have 

 been kept clean, while in those fed by streams and lakes 

 parasitism runs as high as it does among the wild fish. Also 

 where ponds are in series and the lower ones receive their 

 water supply from those above, I believe it is the best policy 

 to winter breeders in the lowest ponds of the series and use 

 the upper ponds for breeding and rearing purposes. The 

 upper ponds may then be drained and cleaned over winter 

 and will be found practically free from organisms carrying 

 parasites when the young bass begin feeding. The clean- 

 ing of the hatching ponds is also good insurance against the 

 water becoming stale from the decomposition of organic 

 matter at the bottom, which sometimes results in the loss of 



