154 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
A very complete statistical investigation into the history, methods, apparatus, 
present conditions, product, and animal value of the salmon lisheries of the Columbia 
has also been made by Mr. W. A. Wilcox', under the direction of Dr. H. M. Smith, 
assistant in charge of the Division of Statistics and Methods of the Fisheries, the 
results of which are embodied and discussed in the report which is herewith respect- 
fully submitted. 
CONDITIONS DETERMINING THE SALMON PRODUCTION OP A RIVER BASIN. 
There are fundamental conditions determining the salmon production of a river 
basin and the nature and extent of the fisheries which may be maintained without 
overtaxing the productive capacity of the river. All the species of salmon which are 
the object of the fisheries are alike under the constraint of a natural law, which com- 
pels them to enter the fresh waters for the purpose of spawning. Some species ascend 
to a relatively short distance above tide water. Others, like the chinook, push their 
migrations to the remotest sources of the rivers and tributary streams, when not pre- 
vented by natural or artificial obstructions. Where the area of distribution is con- 
tracted by the erection of barriers, dams, or other obstructions which the salmon can 
not surmount, the iiroduction of the river is diminished pro tanto, for the reason that 
the young salmon remain for some months in the waters in which they are hatched — 
they must here find their food — and consequently the extent of the feeding-grounds 
open to them will be the measure of nature’s ability to repair the waste occasioned by 
natural casualties and the fishing operations. If there be no contraction of the 
breeding area by artificial obstructions, but, on the other hand, the times, methods, 
and apparatus of the fisheries are such as to intercept or in a large measuie iirevent 
the run of salmon into and up the rivers, then a serious decline in the fisheries is 
inevitable. 
It is possible by fish-cultural operations pursued on an adequate scale, by hatching 
and planting the fry in the head waters of the Columbia and its tributary streams, 
to realize the full productive capacity of the river, so long as eggs can be obtained in 
sufficient numbers to furnish a basis for the extensive operations required. This 
would not be possible, however, if the fishing operations in the lower river practically 
excluded the salmon from the streams to which it would be necessary to have recourse 
to obtain a supply of eggs. It is evident, therefore, that fish-cultural operations can 
not be relied upon exclusively or chiefly to maintain the salmon supply in the Colum- 
bia. The regulation of the times, methods, and apparatus of the fisheries should be 
such as to assure the largest opportunity iiracticable for reproduction under natural 
conditions. Artificial propagation should be invoked as an aid and not as a substitute 
for reproduction under natural conditions. 
THE LIMITS OF MIGRATION OF SALMON. 
The limits of migration of salmon in the Columbia River basin, as determined by 
impassable falls in the larger tributaries of the Columbia and their affluents, is shown 
in the accompanying chart, there being no serious obstructions existing in the main 
river within the limits of the United States. 
The area of distribution is approximately 90,000 square miles. This immense tract 
is drained by innumerable streams of clear cold water, into which the salmon enter 
for the purpose of spawning and up which they ascend till their progress is stopped 
