80 
THE CALIFORNIAN SALMON. 
actuary might calculate from these data. It has been esti- 
mated from close observation, that out of 1000 salmon ova 
left to be hatched in the natural way, only one is allowed 
to reach the marketable stage when the fish is fit for the 
table, as a grilse, or an adult salmon. When a female 
salmon or trout is spawning other trout and salmon lie 
in wait, and devour the ova greedily. In fact ova are a 
most killing bait, and their use is prohibited in England as 
being unsportsmanlike. Eels, lizards, snakes, and birds 
devour them ; droughts and frosts may cause them to 
perish, and when the young fry is hatched it is still more 
liable to danger, as it is extremely helpless in its alevin 
state. Notwithstanding all these perils, were it not for 
the engines of destruction brought against them by man, 
the rivers would swarm with salmon and trout, as has been 
the case in former times in Scotland, and is still so in some 
of the American rivers. If man has destroyed, however, 
science has given him the means to replace, and where only 
one in a thousand have come to maturity naturally, one in 
five may do so with artificial hatching, and rearing to a 
certain stage. 
The mode of hatching salmon and trout now most 
approved of, is to place the ova on fine gravel in shallow 
boxes, and allow a brisk current to flow over them. 
The dead ova must be removed, or they soon generate a 
byssus or fungoid growth, which is fatal to any live ovum 
which it touches. This fungus grows with such rapidity 
that in a few hours it extends its thread-like arms, and 
catches any living ovum within reach, inevitably causing 
speedy destruction of the vital principle. Another 
danger in hatching is the slimy deposit, which falls even 
from the purest water, if not well filtered. The remedy 
for this is a good filtering arrangement, and the use of a 
garden watering pot to wash the ova with a brisk shower, 
