THE SALMON. 157 



Troubled with insects called salmon-lice. 



fishing, frequently fasten rings of gold or silver 

 round salmon, and again throw them into the 

 water. It was by means of these fish that the 

 communication of the Caspian Sea with the 

 Northern Ocean, and Persian Gulf is said to have 

 been discovered. 



As soon as the ice begins to melt on the coasts, 

 the salmon seeks the fresh waters, and is conse- 

 quently found towards spring in the greatest 

 numbers in such rivers whose mouths are nar- 

 row, because their waters run out farthest into 

 the sea. In the warm countries of Europe, it 

 arrives as early as the months of February and 

 March ; in the northern regions not before April or 

 May. The salmon prefers those waters which 

 have a bottom of sand, or pebbles, and a rapid 

 current ; it remains there till towards autumn, 

 and leaving its progeny behind, returns to the 

 sea. Sometimes, however, it passes the winter 

 in the fresh waters, in Sweden particularly, where 

 the rivers are frozen early, and the ice prevents 

 its return. The fishermen have observed, that 

 the salmon fishery is likely to be very productive 

 when they have abundance of insects' adhering 

 to the gills, called salmon-lice ; experience hav- 

 ing shewn that the salmon then enter the rapid 

 rivers in the greatest numbers, in order to get 

 rid of these troublesome companions. Very 

 soon after the salmon have left the sea, these in- 

 sects die and drop off. 



The salmon when entering the rivers, as Dr. 



