BRITISH FRESH-WATER FISHES 
for their fast when they go down to the sea, especially 
between the stages of Smolt and Grilse, and Grilse and 
Salmon. Once having reached the sea it is an oceanic 
wanderer, visiting the North Atlantic and elsewhere, and 
feeding upon herrings, mackerel, sand-eels, and other 
fish. The young prey upon fresh-water shrimps, insects, 
and other aquatic creatures. It is stated that the 
ova (or eggs) will not develop in salt water, hence the 
visits of this species to fresh rivers, and it has been 
proved that it is possible for Salmo salar to pass the 
whole of its life, from birth to death, in fresh water. 
The alevins, or fry, are hatched about March, and at 
first the contents of the yolk-sac, carried on the under 
part of the body, are sufficient to keep them going, as is 
also the case with their cousin, the Trout, shown in 
Fig. 32. Aftera Kelt has spawned it is in a weak condition, 
but has perforce to make its way to the sea. It is also 
subject to more than one disease. Thus weakened, it 
falls an easy prey to human as well as natural enemies, 
and many never reach the sea at all. The descent to 
the sea usually takes place in early Summer, sometimes 
earlier or later, according to the favourability of the 
season. It is not possible to enter into detailed descrip- 
tions of the appearance of the fish during each stage of its 
evolution, and it must suffice if reference is made to the 
beautiful silver coat of the adult Salmon, and the fine 
pink or red colour of its flesh. This latter is due to the 
storage of extra oxygen. ‘The record weight for an adult 
British specimen seems to be 70 pounds, from the River 
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