SALMON. 7 



waters having been purified by deposition in the lakes : 

 on the other hand, rivers swollen by melting snows in 

 the spring months are later in their season of producing 

 fish, and yield their supply when the lake rivers are be- 

 ginning to fail. " The causes influencing this," says Sir 

 William Jardine, to whom I am indebted for much valuable 

 information on the Salmonida, as well as many specimens, 

 " seem yet undecided ; and where the time varies much 

 in the neighbouring rivers of the same district, they are 

 of less easy solution. The Northern rivers, with little 

 exception, are, however, the earliest, a fact well known 

 in the London markets ; and going still farther north, 

 the range of the season and of spawning may be influenced 

 by the latitude. 11 Artedi says , "in Sweden the Salmon 

 spawn in the middle of summer." 



" It has been suggested that this variation in the season 

 depended on the warmth of the waters ; and that those 

 Highland rivers which arose from large lochs were all 

 early, owing to the great mass and warmer temperature 

 of their sources, that the spawn there was sooner hatched. 

 There are two rivers in Sutherlandshire which show this 

 late and early running under peculiar circumstances. One, 

 the Oikel, borders the county, and springs from a small 

 alpine lake, perhaps about half a mile in breadth ; the other, 

 the Shin, is a tributary to the Oikel, joins it about five 

 miles from the mouth, but takes its rise from Loch Shin, 

 a large and deep extent of water, and connected to a chain 

 of other deep lochs. Early in the spring, all the Salmon 

 entering the common mouth diverge at the junction, turn 

 up the Shin, and return as it were to their own and warmer 

 stream, while very few keep the main course of the Oikel 

 until a much later period." 



Dr. Heysham, in his Catalogue of Cumberland Animals, 



