FISHERY INDQSTRIES OF THE UNITED STATES, 1929 709 



strated; waste products of the fisheries have been converted into 

 valuable articles of commerce; better methods have been evolved 

 for the manufacture of certain cured and canned fishery products; 

 and preservatives have been developed which prolong the life of fish- 

 ing nets. All this has stabilized the fishery industries, and the strides 

 made have been so rapid that certain other food industries are looking 

 toward them for guidance, especially those manufacturing frozen 

 food products. 



During the past vear the division's technologists have been con- 

 ducting research mainly on problems relating to the manufacture of 

 fish meal and oil, the feeding value of marine products, the handling 

 and transportation of fresh and frozen fish, and the preservation of 

 nets. These problems have carried the technologists to many parts 

 of the country where conditions are studied first-hand. Thelieed- 

 ville laboratory was kept open all the year, due to the fact that prob- 

 lems in the menhaden industry were involved and required contin- 

 uous study. In addition, a summer laboratory was established at 

 Erie, Pa., to study net preservatives, and a temporary laboratory was 

 in operation at Columbia, S. C, to study the precooling of fish in the 

 South. During the school year the bureau had an employee at Johns 

 Hopkins University, studying the nutritive value of fishery products 

 in cooperation with the nutritional authorities there. 



NET PRESERVATION 



Development of net preservatives under conditions which accelerate 

 deterioration has been continued at Beaufort, N. C, but special atten- 

 tion has been given to investigation as far as possible of preservative 

 material upon twine exposed in actual fishing waters. The work has 

 been concentrated upon trap and gill nets, since the preventable 

 losses from deterioration of these types of gear represent a considerable 

 amount each year. 



TRAP NETS 



The service of trap nets differs from that of all other classes of gear 

 for the reason that part of the fabric is in the water for long periods 

 of time. The w^ebbing is hung upon stakes so that the top portion of 

 the net is above high water and the remainder of the net is under 

 water. Thus part of the net is continually under water and hence 

 may foul badly — the character and extent of growth being dependent 

 upon individual localities. 



In certain localities and especially on the coast of New Jersey, the 

 growth of marine grasses upon trap nets is very serious, due to the 

 formation of a solid wall which resists water movement and by which 

 action the net may be washed out in a storm. Shell growths such as 

 barnacles attach to the net and are objectionable as they may injure 

 the hands of the fishermen when the net is fished. All fouling adds 

 to the weight of the net and hence to the labor of fishing. 



Too little attention has been given to the necessity in trap-net 

 preservatives of a coating on the twine that will oft"er increased resist- 

 ance to mechanical abrasion. Certain portions of a trap net are 

 subjected to severe wear when webbing is hauled over the gunwale of a 

 boat; the wave action, especially in storms, subjects portions of the 

 net to abrasion against the stakes and the damage from driftwood is 

 of no small consequence. 



