MIGRATION OF FISH 93 



pilgrimage down the coast of the British 

 Isles : they appear at a definite time off 

 the different ports, and the fishermen of 

 Scarborough, Grimsby, or Lowestoft know 

 to a week when the herrings will appear off 

 those ports. 



The fish, most of which have probably 

 never travelled the journey before, congre- 

 gate in shoals composed of countless millions 

 of individuals. They have no landmarks to 

 guide them, for the North Sea bed does 

 not present a surface over which they can 

 take definite valleys or hills as a guide. 

 Also the sight of the fish is not sufficient to 

 give it a view of the sea bottom ; for, unlike 

 that of birds, the eye of the fish is so formed 

 that it cannot see more than a few yards 

 in any direction. The senses of smell 

 and hearing are also very poor. We can 

 only account for their ability to make this 

 definite journey of many hundreds of miles 

 on a constant course by their having ac- 

 quired by heredity a mental faculty which 

 mankind does not possess and of which we 

 have no knowledge. 



The herring is the chief migrating fish 

 to be considered, both on account of the 



