2 REPORT OF THE COMMISSIONER OF FISHERIES. 
has been given to the rearing of important species wherever practi- 
cable, and the output of adult, yearling, and fingerling fish was nearly 
50 per cent larger than in any previous year. 
The importance of the Bureau’s fish-cultural operations, however, 
must not be gauged by the results during any one year, but by the 
average for a series of years. Peculiar seasonal conditions often 
materially modify the work of particular stations, sometimes favor- 
ably, more often unfavorably, and give an erroneous impression as to 
its extent. It usually transpires that a year which is characterized 
by a greatly diminished yield of certain fishes is noteworthy for an 
augmented output of others, so that the aggregate distributions 
remain normal. This point, which has frequently been emphasized 
and illustrated in previous reports, was exemplified anew in 1904, when 
an exceedingly poor season for shad and white-fish was-offset by the 
largest collections of eggs of Pacific salmons and flat-fish ever known. 
An important feature of the work of artificial propagation, which 
has often been referred to but can not be too strongly emphasized, is 
that an exceedingly large percentage of the young fish hatched annu- 
ally are from eggs taken from fish that have been caught for market, 
and hence would be totally lost were it not for the efforts of the 
Bureau. To the many hundred millions of young food and game 
fishes thus produced must be added many more millions resulting from 
the superiority of artificial propagation over natural propagation in 
the matters of fertilizing and incubating eggs and of safety of the 
young. 
STATIONS OPERATED. 
The fish-cu:tural work of the Bureau in 1904 was conducted in 26 
states, at 49 stations and substations. In respect to their output, the 
substations are in most cases of equal, in some cases of greater, impor- 
tance than the stations, but their equipment is less complete and for 
administrative purposes they are subordinated, and their personnel 
supplied from the stations to which they are attached. 
The demand and the local facilities determine the proportion of 
effort directed toward the cultivation of the important commercial 
species. During the past year the salmons were propagated at 11 
stations; white-fish at 7; lake trout at 5; shad at 4; pike perch at 3; 
cod at 2; flat-fish at 2; striped bass, white perch, and yellow perch at 
1 each; and the lobster at 2. 
THE SPECIES CULTIVATED AND DISTRIBUTED. 
The number of species now regularly cultivated and distributed by the 
Bureau is upward of 50, and the artificial propagation of new fishes is 
being taken up asthe work increases and the demand arises. A full list 
of the species handled in 1904 follows, from which it will be seen that in 
every section, so far as the existence of hatcheries permits, the supply of 
the important food and game fishes is being increased by the Bureau’s 
