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destroys not only anadromous fish, but almost all. valu- 
able river fish as well—for in their search for food, 
and to propagate their species, almost all river fish are 
more or less migratory at certain seasons of the year. 
In proof of this, all sorts of fish inhabiting the Hud- 
son River are-seen passing up the fishway recently 
constructed on the Mechanicville dam, and I have seen 
them pass up many other fishways, both in Canada 
and in this country. 
The dam, moreover, by preventing the fish from 
ascending ae river, causes them to accumulate below 
the obstruction, where they fall an easy prey to the 
industrious poacher of every description. 
At this same point also, are found mill refuse, saw- 
dust or poisonous drugs thrown off by the mills and 
factories, which, from being in bad company, bear much 
of the odium fairly belonging to the more deadly dam. 
Sawdust and other wooden substances may be dis- 
missed as being comparatively harmless, while the poi- 
sonous drugs and dyes are usually confined to one side. 
of the river, the fish avoiding them by passing up along 
the opposite shore, while on rapid-running streams inter- 
sected with dams or falls, the water reoxygenates itself 
at a short distance below the point of contamination. 
So that, unquestionably, the dam and the poacher are 
the greatest hindrance to the improvement so much 
needed and sought after. 
Much has been and may be done in restocking de- 
pleted waters by the artificial propagation of fish, but 
where dams exist little improvement has been effected, 
especially in anadromous fishes, as they descend to the 
sea, but cannot return to their native rivers, or to the 
upper portion of them. ‘Therefore, to open the dams 
with proper fishways, is to add greatly to the value of 
pisciculture, as well as to directly increase the quantity 
of fish. 
Shad and river herring usually spawn in the still 
