42 REPORT OF THE COMMISSIONER OF FISHERIES. 
although the primary purposes have been to determine if shad of 
different rivers or of different brood regions present distinguishable 
racial differences and to obtain information as to the extent of the 
~ ecoastwise movements of the fish. Many data have been accumulated 
and many specimens secured, all of which must form the basis of 
subsequent detailed studies before exact conclusions can be drawn. 
Associated with the shad and herring and having similar habits is 
the glut herring, a species of considerable abundance but one which 
until recently found only a limited market um the localities in which 
taken. The past few years have witnessed a marked increase in 
value and diminution in numbers. During the past season experi- 
ments were made by an assistant in cooperation with fish culturists 
to ascertain the best methods of handling and hatching the eggs, 
and the results have indicated that the artificial propagation of the 
species on a large scale is feasible. 
The detailed study of the life history of the salmon of the Sacra- 
mento and Columbia Rivers has been continued and the field work 
is practically concluded. With the study of accumulated data and 
the preparation of the report during the ensuing fiscal year, it is 
expected that conclusions will be reached that will guide our fish- 
cultural operations to a stage of greater efficiency. In the direction 
of these studies the investigator has had not only the benefit of the 
most expert counsel but the sympathy and suggestions of practical 
fish culturists. 
INVESTIGATIONS RELATING TO FRESH-WATER FISHES. 
The field of fresh-water fish investigations has been too little 
touched, although the immediate opportunities of domestic fish 
culture are probably greatest among fresh-water forms. No one 
assumes that the great complex of streams and abundant lakes and 
ponds are productive to their maximum capacity, but rarely is due 
care taken to conserve in practicable ways the conditions m them 
favorable to the growth and eee of fish. This phase of the 
general problem of fish production is not yet adequately realized 
nor are the principles satisfactorily developed. 
That the streams, lakes, and ponds should be stocked and restocked 
with fish is an ever growing demand which indicates the widespread 
interest in such fisheries, whether they serve as a means of recrea- 
tion or as a source of food. The stocking and emia of waters 
is, however, not usually the principal desideratum. In specific | 
instances the actual condition to be slic acini be due to an over- 
abundant stock. Just as agriculture has long since passed the stage 
where increased production is sought primarily through the planting 
of more seed in a given area, so it is incumbent to give proper atten- 
tion to promoting a favorable condition for the growth of fish, look- 
ing intelligently to the maintenance of suitable condition of physi- 
cal environment, abundance of food, proper association of species, 
and a correct proportioning of numbers and variety of fishes to the 
biological capacity of the water. 
The fishery problems of fresh water are undoubtedly simpler than 
those of the seas, but they are certainly less directly approachable 
than the problems of agriculture which have met their solutions. 
It is not surprising, therefore, that, throughout the country in mat- 
