THE LOCH PROBLEM 195 
experience alone can decide the number of fish 
which should be put into the loch every year. 
Spring is the best time to do this. The number of 
fish which should be put in will obviously depend 
chiefly upon the amount of food in the loch and 
the number of fish caught, and destroyed by their 
enemies, during the preceding year. In many lochs 
there are stones under which the small trout can 
find protection from the large ones, but where 
there is no protection it is worth while to put 
stones or small di'ain tiles round the edge of the 
loch. 
In lochs where, as is usually the case, the fish 
can spawn effectively the fish increase so rapidly 
that there is not a sufficient supply of food, and 
the result is that the loch is filled with hungry 
small trout. When it is remembered that it is 
reckoned that every spawning trout produces 
800 to 1000 eggs for every pound of its weight, 
some idea is obtained of the rapidity with which 
fish increase. In many lochs Nature intervenes 
and the enemies of trout — divers, herons, ducks, 
otters, etc. — keep the numbers down, sometimes 
to the point of extinction ; in other lochs, owing 
to the severe frosts and other causes, it is only 
occasionally that the eggs are hatched out. 
