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. After a 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 

 66 



