FISHES I 5 7 



laboriously round the north of Great Britain just as their 

 ancestors must have done countless centuries before the 

 Channel came into being. 



The Salmon [Salmo salar) is another fish that illustrates 

 to a remarkable degree the conservative manner in which 

 certain fishes direct their courses. As is well known, 

 this fish although spending some years in the sea, invariably 

 returns to the river of its origin when the time comes to 

 propagate the species. The late Frank Buckland has given 

 a remarkable instance of this blind homing instinct in a 

 letter published many years ago. He wrote : " A friend 

 of mine who owns a well-known island on the west coast 

 of Scotland netted a certain pool in his fishing and out of 

 a number of fish caught he carefully marked some twenty 

 or thirty. He then put these fish on board his yacht and 

 sailed right round his island, then up a creek to the mouth 

 of a river. The Salmon were transferred up the river, 

 which although close to the river in which they were 

 caught was in no way connected with it, having a different 

 watershed. It is as though the Salmon had been carried 

 from one heel of an enormous horseshoe round to the other 

 heel and then taken right up into the middle of the horse- 

 shoe and let loose. During the season that these fish 

 were transferred some of the marked fish were caught 

 in their own pool with a net and one with a rod. On 

 examining the map I find that these fish must have come 

 back again to their own river, a circuit of forty miles 

 at least from the lake where they were turned out, and they 

 must have passed six or seven tributaries which they did 

 not ascend, although there was nothing to prevent them.' , 



Perhaps the most remarkable of all fish migrations 



