478 Proceedings of Royal Society of Edinburgh. [sess. 
river is to let a good number of fish up it to spawn naturally every 
year, and that this treatment produces results comparatively 
quickly; in other words, that the administrative policy of the 
Canadian Government, rather than salmon culture, has chiefly 
caused the improved catch in these rivers. How far this is true 
elsewhere, a study of the three chief salmon producing rivers in the 
United States may help to show. 
Penobscot (Table, p. 477). — In the Penobscot there are a number 
of obstructions, — so many that it has been claimed that all the fish 
caught in it are artificially produced. This, however, is not the case, 
as some 200 fish were observed spawning naturally upon the Pen- 
obscot in the autumn of 1899 (U.S.F.C., Report for 1901, pp. 9 and 
36). None the less, the obstructions are numerous and difficult 
to surmount, and possibly for this reason the yield of the Penobscot 
shows so large a decrease, amounting in 1899 to nearly 75 per cent. 
As will be seen from note d, it is reported to have improved since. 
Sacramento (Table, p. 479). — Much controversy has raged as to 
the cause of the failure of the Sacramento yield during the period 
1884-95. It has been often ascribed to the stoppage of artificial 
culture in 1883 and the following years, but propagation was discon- 
tinued at that time, because salmon no longer appeared in the upper 
reaches, and over-fishing is said by several competent American 
authorities to have been the reason of their disappearance. Recently, 
however, the Sacramento seems to have been improving. In the 
early nineties the capture of the young of fish was prohibited, and the 
close time extended and altered so as to enable more spawners to 
run. Measures for the protection of natural spawners were also taken, 
and the number of fry artificially propagated enormously increased.* 
Columbia (Table, p. 480). — The Columbia shows a very large 
decrease, almost universally ascribed in America to over-fishing. 
It is too early yet to discern the effect of the colossal planta- 
tions of fry recently attempted upon this stream, but it should 
be noted that, whereas American fish culturists generally argue 
that the best results can be obtained by retaining the fry in 
ponds until the yearling stage is reached, this has not yet been 
possible in the Columbian hatcheries, owing to the immense 
amount of space which would be required for the rearing 
* The writer cannot give the exact date of these amendments to the laws. 
