FISHERY PROBLEMS 183 



of the Polar current and the Cabot current. The Iceland 

 banks surrounding the summits of the submarine moun- 

 tains are fed with the warm waters of the Gulf Stream 

 and the cold waters of the Polar current. The Wy- 

 ville Thomson ridge first divides and then mingles the 

 warm and cold currents, and to this mixture is due 

 the wealth of the North Sea shoals. The Atlantic 

 continental plateau is watered by warm and by luke- 

 warm waters. The Channel and the Mediterranean 

 undergo great fluctuations of superficial temperature 

 in the course of the year. We must not forget that 

 nearly all these banks receive the fresh water of rivers 

 also : the Dogger, the water of the German rivers ; the 

 Bay of Calvados, the water of the Seine ; while the other 

 grounds are affected by the Loire, the Gironde, the 

 Rhone, the Po, &c. Let us not overlook the bays, 

 estuaries, creeks, lagoons (so rich in fish), and fishponds 

 those homes of fry, where the water is by turns warm and 

 cold, and always brackish. Are fishing-grounds reported 

 out at sea, on the very verge of the continental plateau ? 

 If so, you will find that in their immediate neighbourhood 

 there are vertical currents, whether in the Atlantic or the 

 Mediterranean ; currents which bring cold water to the 

 surface. You will also find a clashing of warm and cold 

 currents, such accidents as the encounter or separation of 

 currents. Everywhere you will find water in movement, 

 but not in violent movement ; everywhere water which is 

 disturbed, water whose physical qualities are changing; 

 everywhere a state of unstable equilibrium, of continual 

 crisis. In a word, fishing-grounds are regions in unstable 

 equilibrium and in a state of crisis.* 



1 The expression "fishing-ground" is here used in its widest 

 acceptation ; that is, as meaning any locality where large quantities 

 of fish are caught, whether on the surface or on the bottom. 



