202 The Under-Water World 



progressive. In Great Britain similar ex- 

 periments have been made with plaice 

 in Loch Fyne, but these being of a 

 semi-private venture have remained at 

 the experimental stage. It was found 

 that young plaice liberated in the Loch 

 Fyne area, immune from the enemies that 

 continually attack such fish in the sea, 

 showed a comparatively small mortality. 

 Whilst few practical steps have been 

 taken in this country to protect fish 

 which might be turned into a regular 

 food supply, efforts have been made to 

 follow the movements of our food fish 

 by the system known as " marking." 

 The idea is not new, for Izaak Walton, 

 in 1653, wrote : " Much has been ob- 

 served by tying a ribbon on the tail of 

 some young salmon which have been 

 taken in weirs as they have swimmed 

 towards the salt water, and then by 

 taking a part of them again by the low 

 mark at the same place as they returned 



