REPOET OF THE COMMISSIONER OF FISHERIES VII 



varying length of life of twine so treated. Practical tests of this 

 nature, cooperated in by the fishermen, are now in progress at sev- 

 eral points on the Atlantic seaboard and on the Great Lakes. These 

 tests are expected to show the advantages and disadvantages of using 

 copper oleate under practical conditions and to indicate what modi- 

 fications in its use are necessary for different kinds of gear under the 

 widely varying conditions to which they are subjected. 



Cordage manufacturers are finding copper oleate to be a good 

 preservative and anti- fouling agent for rope. At least one company 

 now sells, for marine use, rope treated with this material. 



IODINE CONTENT OF PRESER^^D SEA FOODS 



In a paper published during the last fiscal year (Bureau of Fish- 

 eries Document No. 967) it was shown that fresh sea foods contain 

 a higher percentage of iodine than do other common foods. The 

 suggestion was made that since goiter and other thyroid disorders 

 are caused by a lack of ingestion of iodine, the liberal use of sea 

 foods in the diet should be an effective preventive of these disorders, 

 especially in so-called goiterous belts where the iodine content of the 

 water and foods is below normal. The amount of iodine necessary 

 to prevent goiter is very small — only about one part in 3,000,000 parts 

 of the body weight — but it is important that this balance be main- 

 tained. 



Many of the goiterous belts are so located, however, that it is 

 rather difficult for the inhabitants to obtain marine fish in the fresh 

 condition. Much of the marine fish which they consume has been 

 preserved in some manner, such as canning, salting, or smoking. The 

 question naturally arose as to whether these preserved products 

 contain iodine in quantities comparable to that in fresh fish, and 

 analyses were then made which indicate that they do. The results 

 of these analyses were published in Bureau of Fisheries Document 

 No. 979. 



TREPARATION OF STURGEON CAVIAR 



During the sturgeon season on the Delaware River the bureau took 

 advantage of an opportunity to give demonstrations, for the benefit 

 of fishermen and others, of the Russian methods of preparing caviar. 

 These were conducted at a number of places by a Russian expert 

 skilled in foreign methods. 



Russian caviar is of the highest quality, and a knowledge on the 

 part of our fishermen of the methods used in its preparation should 

 assist them in putting up a first-class product. 



CRAB FISHERY OF THE CHESAPEAICE BAY 



At the urgent solicitation of men in the crab industry of Chesa- 

 peake Bay, who were becoming alarmed by the marked decrease in 

 the stock of crabs, the bureau undertook to investigate their problems. 

 A preliminary survey was made, from which it was found that there 

 is a loss of over 50 per cent in converting the so-called " peeler 

 crab " into the " soft crab," due to careless buying methods. A com- 

 parison of the fragmentary information available also indicated a 

 distinct relationship between the catches of crabs in the States of Vir- 

 59260—25 2 



