172 U. S. BUREAU OF FISHERIES 



the work of the 1928 season at Erie, since it showed that treated nets 

 do catch fish much the same as untreated "white" ones in spite of 

 the very decided local opinions to the contrary. The prejudice 

 against treating gill nets is so marked that only one man near Erie, 

 Pa., has been found using any preservative treatment. He is Clarence 

 Jackway, of Westfield, N. Y. In the past Mr. Jackway used the 

 copper oleate treatment for gill nets, but abandoned it as unsatisfac- 

 tory. His opinion in this respect, no doubt, was strengthened by a 

 reluctance to pay the added cost of this relatively expensive treat- 

 ment. He now uses a solution of coal tar in kerosene, which is 

 applied by pouring the mixture over the dry nets stored in their 

 regular boxes. After a short period of drainage the nets are reeled up 

 to dry in the usual manner. After two days of exposure on the racks 

 they are ready for use. 



The tar-kerosene treatment used by Mr. Jackway is prepared by 

 warming 5 parts of kerosene gently with 1 part of coal tar. It might 

 be noted here that in this net treatment, as in others using coal tar, 

 samples having the least "free carbon," or residue insoluble in benzol, 

 are best for preserving nets. The warm mixture of tar and kerosene 

 is allowed to settle until the solution overlying the insoluble residue 

 in the bottom may be poured off ready for use. This treatment is 

 applied to the nets two or three times yearly ; it is relatively cheap — 

 the expense being estimated at about 75 cents per net per year. Mr. 

 Jackwaj^ reports that nets treated in this manner last two or three 

 times longer than untreated ones, and that the main objection to the 

 treatment is the shrinkage it causes. The fishermen want to use the 

 smallest possible mesh that will pass official inspection as to size of 

 mesh, but can still use treated nets and be safe by ordering a larger 

 sized mesh for those nets which are to be subsequently treated. 



The modified tar-kerosene treatment was applied to two alternate 

 nets of a gang of "bull nets" which were used regularly for approxi- 

 mately three months. The remaining two nets of the gang were left 

 untreated so as to serve as a means of comparison. A second gang of 

 "bull nets" was prepared with two nets treated with preservative No. 

 2850. This treatment originally was designed for trap nets, but 

 produced a treated twine flexible enough so that it was deemed to be 

 suitable for a practical fishing test. The two gangs of nets were 

 placed with others and fished in the usual way. The catch was 

 counted carefully each time the nets were fifted and the results Hsted. 

 Tables 1 and 2 show the catch for gangs 1 and 2 respectively. Upon 

 examining the results for gang 2, it is seen that the brown nets caught 

 practically as many fish as their untreated neighbors. Upon exam- 

 ining the results for gang 1, it is seen that the black nets did not catch 

 as many fish as the near-by untreated controls nor as many fish as the 

 brown nets of gang 1. 



It is difficult to say just what effect the color of nets has upon the 

 actions of fish near by. In this particular case it seems safe to say 

 that both nets are dark enough that the difference between brown and 

 black is not as important in influencing the behavior of the fish as the 

 degree of darkness of the thread, for the reason that the nets are used 

 deep in the water under conditions where there is so little light at best 

 that it would be difficult to distinguish difference in terms of color 

 alone. Everyone has observed how difficult it is to say just what 

 "color" a dark suit really is when beheld in a poor light. The visual 



