20 U. S. BUREAU OF FISHERIES 
attributed to undernourishment, was characteristic of any particular 
fishing locality, samples of small, medium, and large halibut were 
obtained by the Commission and analyzed in our Seattle laboratory. 
Samples were taken periodically over the fishing season from area 
no. 2 where the halibut tend toward localization and area no. 3 where 
the halibut are known to be migratory. To date chemical analyses 
have been made of the fat content of the halibut taken from area no. 
3. These failed to disclose any consistent relation between fat con- 
tent and locality of capture. 
It was found that the fat content of large halibut was in general 
higher than that of medium halibut and medium halibut likewise 
had a higher fat content than small halibut. There were, however, 
quite wide variations in fat content in each size group. 
USE OF ANTIOXIDANTS IN PRESERVING FOOD-FISH PRODUCTS 
As a part of the studies being carried on by the research associate 
of the Musher Foundation in our Seattle laboratory, a series of sam- 
ples of frozen salmon and halibut, mild-cured salmon, kippered sal- 
mon, canned salmon, and Alaska salt herring were prepared in which 
cereal flours or cereal flour extracts were added for the purpose of 
retarding the development of rancidity. These are being stored pend- 
ing observation from time to time. To date examinations on samples 
of canned salmon showed that where oat flour was used or where an 
extract of oat flour was sprayed on the inside of the can, there was a 
noticeable lessening of the characteristic fish odor and taste of the 
treated product. Whether this difference in odor and taste will con- 
tinue after extended storage periods cannot be stated at this time. 
IDENTIFICATION OF CANNED SALMON ae 
From time to time regulatory bodies and others associated with the 
marketing of canned salmon are called upon to check the identity of 
the species of salmon used in canning. At present this is done largely 
on the basis of experience in judging the appearance of the canned 
product. Some years ago, however, there appeared in the literature 
an article suggesting the possibility of identifying the various species 
of salmon by the iodine number of the oil in the flesh. In recent 
studies by the Bureau in which the physical and chemical character- 
istics of salmon waste oils were determined a similar grouping accord- 
ing to iodine number was observed. It was noted also that the refrac- 
tive index and iodine number of each sample were very closely corre- 
lated. In view of the fact that the determination of refractive index 
might provide a very simple means for checking identity, technolo- 
gists of our Seattle laboratory have begun the collection of samples of 
oil from canned salmon for the purpose of determining the probable 
merit of the method as a positive means of identification. 
CANNING AQUATIC PRODUCTS 
During 1936 the experimental studies in canning were continued 
with special attention to the development of improved methods for 
canning fishery products in the home or under noncommercial condi- 
4“The determination of the hexabromide and iodine numbers of salmon oil as a means of identifying 
the species of canned salmon’’, by H. S. Bailey and J. M. Johnson, Journal of Industrial and Engineering 
Chemistry, vol. 10, pp. 999-1001 (1918). 
