PERCH-LIKE FISHES I45 



evidence, were advanced to account for their seasonal move- 

 ments. Most of the classical writers, however, as well as those 

 of medieval times, agreed in looking upon the Tunny as an 

 Atlantic fish, that entered the basin of the Mediterranean in 

 the spring, passed eastwards to the Black Sea, where it spawned, 

 and then turned back and regained its oceanic home. Modern 

 methods of research have done much to elucidate the whys 

 and wherefores of the movements of the Tunny, but much of 

 the picture still remains to be completed. Enough is known, 

 however, to show that the ancient idea outlined above was 

 far from correct. 



Concentrations of Tunnies take place for spawning purposes, 

 but the main migrations are firmly linked up with the move- 

 ments of the shoals of fishes on which they prey, which in 

 their turn are dependent upon the movements and concentra- 

 tions of the small planktonic animals on which these smaller 

 fishes subsist. The Common Tunny is present in the Mediter- 

 ranean throughout the year, and probably also in the warmer 

 parts of the Atlantic, but in the more northerly parts of the 

 Atlantic its occurrences are distinctly seasonal. In April, 

 May and June the fishes congregate for spawning, such 

 gatherings taking place in the area between Sicily, Sardinia 

 and Tunis, in the Atlantic just outside the Straits of Gibraltar, 

 and probably in other places where conditions are suitable for 

 the development of the eggs. Spawning is at once followed by 

 a recuperative feeding migration, the spent and hungry fishes, 

 which have not taken food for some time, dispersing in all 

 directions, intent upon nothing but obtaining nourishment. 

 In European waters there is a definite northerly movement 

 during the suihmer months, and Tunny are only to be found 

 in such places as the North Sea and the Norwegian coast 

 from July to about October. Exactly the same thing happens 

 in the western Atlantic, where the shoals arrive on the coasts 

 of Nova Scotia during July. 



The Tunny that make their appearance in the North Sea 

 during the latter part of the summer may be observed in 

 shoals consisting of 20 or 30 individuals, feeding ravenously 

 on herrings escaping from the nets of the fishermen. These 

 fish have taken a long journey from the breeding-grounds. 

 They appear at the mouth of the English Channel at the evA 



