1902-3.] Mr Win. Murray on Salmon in American Rivers. 469 
Statistical Evidence regarding the Influence of Artificial 
Propagation upon the Salmon of the American 
Rivers. By William Murray. Communicated by Dr D. 
Noel Paton. 
(Read July 6, 1903.) 
The materials for this paper upon the Influence of Artificial Pro- 
pagation on the Salmon of the American Rivers have been gathered 
from an examination of the salmon fishery statistics of Canada and 
the United States of America, where salmon culture has been ex- 
tensively pursued. 
The rivers examined include five principal rivers, or districts of 
rivers, in Canada, in which salmon fry have been liberated, — the 
Penobscot, the only river in eastern America which has now an 
appreciable run of salmon, the Columbia and Sacramento upon the 
Pacific coast. The salmon bred in the Columbia and Sacramento 
are of course members of the Pacific varieties, and, as such, differ 
from the fish as known here. Of the varieties hatched, the Chinook 
or Quinnat is the chief, and this fish has been planted in some of 
the other and smaller rivers of the Pacific coast, but the difficulty 
of obtaining sufficient statistical information has made the inclusion 
of these streams in this review inadvisable. The statistics con- 
sidered cover a long period of years, varying from twenty to nearly 
thirty. Returns for consecutive years are not collected in the 
United States, but for each fourth or fifth year, as the demands 
upon the time of the central department permit. In Canada, on 
the other hand, the returns are made yearly, and upon some streams 
extend backward over a very long period, forming a most valuable 
informative collection of salmon fishery precedents. The statistics, 
which have been studied with the object of discovering what, if 
any, has been the effect of artificial culture upon the productive 
powers of these rivers, seem, as a whole, to throw up two main 
conclusions : — 
(1) Amongst the rivers where salmon culture has been estab- 
lished, those have maintained or increased their yield where re- 
strictive regulations regarding netting and close times have been 
enforced, combined with facilities for natural reproduction. 
