NET DETERIORATION IN LAKE ERIE 



173 



powers of fish and their habits in this respect are something concern- 

 ing which Httle is known. 



It is reported that whitefish and yellow pickerel are best caught in 

 light-colored trap nets, and that ciscoes refuse to enter trap nets at 

 all. This latter effect may be due to the color of the net, to the tend- 

 ency to flee from the sight of obstructions, or possibly the "smell" of 

 a net. 



Sometimes the lake water is not very transparent, hence neither 

 visibility or color perception would be a very large factor in influencing 

 the fish. It may be that the texture of the net was the actual deciding 

 factor. While experience has shown Mr. Jackway's treatment to be 

 good, a modified tar-kerosene treatment was used in these experiments, 

 since previous experiments had shown the preservative action of the 

 tar to be transient — seldom lasting over two months at best. There- 

 fore, 6 pounds of coal tar and 3 pounds of pine tar were mixed with 5 

 gallons of warm kerosene and allowed to settle. Six pounds of cuprous 

 oxide were added to this solution and the clear solution poured off. 

 Some of the heavier particles of cuprous oxide remained behind; the 

 most finely ground pigment is necessary in this modified treatment, 

 which was designed to have the minimum of heavy or coarse material. 



Table 5. — Catches of nets in series' 1, July 19 to September 9 



It seems that the only marked difference between the catch of the 

 various nets is found in the number of whitefish and burbot taken by 

 the nets treated with No. 2850 preservative. This dift"erence for 

 gang 1 seems large enough to be called significant, but gang 2 shows 

 so little difference between nets that when one considers that fish 

 run in schools which often hit nets in irregular groups, it seems 

 reasonable to conclude that treated nets can be safely used for herring 

 fishing in Lake Erie with, no danger of decreasing the catch except 

 that fewer whitefish probably will be taken at the same time. Until 

 more extensive future observations give favorable results, whitefish 

 nets should not be preserved with brown or black treatments. This 

 is the safer course to pursue. The data are not sufficient to enable 

 one to make a positive statement, and it appears possible that the 

 difference between dark and light nets might be very small. 



In this connection it should be stated that treatment No. 2850 was 

 designed for pound and trap nets and was used on gill nets with the 



