34 U. S. BUREAU OF FISHERIES. 



it extracts the water necessary for things to live on. The rule is that 

 a stronger salt solution will extract water from a weaker juice where- 

 ever it comes in contact with it. 



This principle is made use of in many ways. Every fisherman 

 knows that salt draws the water out of fish in the curing process. 

 It is not so apparent, but it is equally true, that it draws the water 

 from and kills the bacteria that would otherwise cause the fish to 

 decay, and thus preserves it. Any equally concentrated substance 

 would do the same. Thus sugar is used in very concentrated sirup 

 to preserve fruits; if the preserves were sufficiently diluted with 

 water, bacteria coukl live in them and they would spoil. 



In this way salt preserves nets. It dissolves in the moisture on the 

 threads to make a very strong solution; this strong solution kills 

 bacteria and other small organisms by extracting the water from 

 them. From this it is hardly necessary to say that the salt should 

 be applied generously, and preferably in the dry condition, to a wet 

 net. If brine is used, it should be very strong. 



But salt will not prevent heating in an oily net that ha^ just 

 caught very fat fish, such as herring. The heating is caused by the 

 air working on the fat. The only way to prevent this heating is 

 either to get rid of the fat or to prevent the air from getting to it. 

 Aboard a vessel it is not alwaj^s convenient to wash the net out imme- 

 diately, nor is there room to spread the net (if spread, the heat, of 

 course, escapes as fast as produced and no harm is done). Bull 

 (1905) suggests that to prevent this heating of recently used herring 

 nets aboard a vessel, there be provided a wooden tank with a tight- 

 fitting lid, filled with water or salt solution, and that the net be put 

 into this and covered over with the lid until there is opportunity to 

 wash it. The water or salt solution keeps out the air and prevents 

 heating. The cheapest obtainable grade of salt may be used, since 

 there is not likely to be anything in it that is injurious to net-s. 



Nets, as every fisherman knows, should be washed and dried at 



every opportunity. 



CONCLUSION. 



The most important methods of preserving nets are tanning, for 

 which an improved recipe is given on page 22; tarring, found on 

 page 26; and creosote, found on page 30. Other methods are also 

 given. 



CITATION OF LITERATURE. 



In the preparation of this paper the following publications have been con- 

 sulted and material therein quoted or reproduced here and translated where 

 necessary. Those interested in pursuing the subject are referred to them for 

 further details. 



Aase, Hans. 



1912. Barkning. Norsk Fiskeritidende, Side Aargang, pp. 169-172, 1912. 

 Bergen. 

 Babclay, M. 



1904. Barkning og O'.jing af Sildegarn paa hoUandsk INIaade. Norsk 

 Fiskeritidende, 23de Aargang, pp. 448-458, 475-485, 1904. Bergen. 

 1905c. Cm Barkningsmetoder. Keferat fra Fiskerni0det paa Sortland den 

 lite og 12te Juli. 1905 ; ved IM. H. Stoltz. Norsk Fiskeritidende, 

 24de Aargang, pp. 233-239 (discussion of paper, pp. 238-239), 

 1905. Be.-gen. 

 19056. Sildegarnenes Konservering i England og Skotland. Norsk Fisk- 

 eritidende, 24de Aargang, pp. 372-376, 1905. Bergen. 



