BUREAU OF FISHERIES XXV 
Columbia River. Fingerlings have been marked by removing various 
fins and have been liberated under varying conditions in the river. 
The herring fishery of Alaska has been receiving greater attention 
recently. The growing use of herring for food and manufacture 
into oil and meal has aroused considerable anxiety concerning the 
danger of depletion. Biological investigations of the herring begun 
in the spring of 1925 have been continued, and extensive studies of 
the segregation of the various races have been made. In addition to 
the studies of the physical proportions of the fish as a means of dis- 
tinguishing the racial units of the fish population, which were made 
last year, a tagging program has been undertaken. During the 
spring of 1927, 3,000 herring were tagged, and studies of the early 
development were begun by making tow-net collections of larval 
herring. 
The only other subject of detailed study by the bureau was the 
razor clam. Studies have been conducted on representative beds 
throughout the Pacific coast, and several reports already have been 
published outlining the general features of the life history of this 
clam. During 1926 and 1927 a comprehensive study on rates of 
growth, according to latitude, on the Pacific coast has been in prog- 
ress, and data of direct use in regulating the fishery in Alaska have 
been collected. Thorough annual observations of the more important 
beds are made and the trend and abundance of the resource accu- 
rately determined, and regulations governing the fishery in Alaska 
for the following year are drawn up in accordance with actual needs. 
FISHERIES OF THE INTERIOR 
The investigations of the inland fisheries are centered at the fish- 
eries biological laboratory at Fairport, Iowa, for the Mississippi 
River district, and at the University of Michigan, Ann Arbor, Mich., 
for the Great Lakes. Investigations at Fairport are concerned chiefly 
with the artificial propagation of fresh-water mussels, which provide 
the raw material for the manufacture of pear] buttons and novelties, 
and with studies on the pond culture of fresh-water food fishes. 
The most important work along this line conducted at the Fairport 
laboratory in recent years consists in developing a nutrient solution 
that serves as a medium for the growth of larval mussels without 
passing a period of parasitic life on the gills of various fishes. In 
addition to the trough-cultural methods devised as a result of earlier 
studies, great numbers of fish rescued from overflowed lands in the 
Mississippi Basin are infected with the glochidia of mussels before 
they are returned to the river. This work of the bureau has re- 
ceived enthusiastic support from the button industry, as the increas- 
ing cost of labor and the scarcity of raw materials are proving a 
serious handicap to the industry. 
The process of rearing larval mussels in a nutrient solution, evolved 
by Dr. Max M. Ellis, of the University of Missouri, promises greatly 
to simplify the propagation work of the bureau and tremendously 
increase the output of juvenile mussels at an age and stage of develop- 
ment that virtually insure survival. Moreover, it will permit their 
being planted in areas suited to their rapid development, and which 
can be controlled, thus making mussel farming on an extensive scale 
