flow to obtain it. 289 
itself on its return from the river, and it has also to accumulate a 
sufficient amount of fat to be of service to it during the time it 
remains in the fresh water on its next visit. In going to the sea,. 
salmon get a thorough change of water as regards specific gravity, 
temperature, composition, and products. The return of the fish 
to the rivers is an exceedingly important economic question, some 
rivers being early and some being late, and some—no wonder that 
it should be so—are getting later. 
A great desire has been expressed from time to time to make 
a late river earlier. The way to do this, if it can be done at all, 
is to deal with the river as well as with the fish. The influences 
which affect the habits and migrations of the salmon must be 
carefully considered before attempting to deal with so difficult a 
problem, but I would by no means discourage attempts to make 
improvements in this direction. I have seen quite enough 
myself to be led to the belief that it is quite possible to improve 
some of our rivers that formerly were earlier than they are at 
present. 
There are two main influences which more or less affect the 
migrations of all fishes, viz., food supply and reproduction of 
species. These are the primary elements to deal with in working 
out any questions bearing on the improvement of fisheries. We 
know that these items have a very important influence on their 
welfare, and we know also that there is very much to learn 
concerning them. In some cases the more we work out the 
variety of facts connected with the migration of fishes, the more 
complex do they seem. 
We have learned a great deal about the migrations of birds of 
late years, but, living as they do in the air, we can to a great extent 
follow their movements, by having observers all over a country or 
continent, and so we ascertain their exact line of flight. It is not 
so easy to follow the salmon through all his wanderings, but it is 
a work that has to be done, and it is not very complimentary to 
the advanced knowledge of the nineteenth century that we know 
as little about the “‘king of fishes” as we do. 
We know that the salmon in the “ parr” stage, as we find him 
in our rivers before he has made any acquaintance with the sea, 
feeds well. We know, also, that about the month of May these 
U 
