184 SEA FISHERIES 



This is the idea which irresistibly issues from these data. 

 But the definition of a fishing-ground thus formulated is 

 unilateral. It refers to the physical but not to the bio- 

 logical factors. We must now include the latter ; we 

 must consider how the fish behave upon the fishing- 

 grounds ; that is, if we wish our definition to assume the 

 value of a law. 



It is of course understood that the edible species never 

 leave the immediate neighbourhood of the continental 

 plateau ; and we know that at spawning time they as- 

 semble in closely packed phalanxes and draw near to the 

 shore. M. Cligny has shown that after spawning the 

 shoals of herring disperse, without leaving the waters 

 in which they have just been manoeuvring, and that 

 isolated individuals, still extremely voracious, travel 

 between two waters, and are thus inaccessible to all the 

 usual tackle of the fisherman. It is no less certain that 

 the fry make for the coast, wherever they may be hatched. 

 Very young flat-fish are found exclusively near the shore. 

 As they grow up they scatter a little from the shore, but 

 they return to spawn. In the month of April the sword- 

 fish rise to the surface and steer for the Calabrian coast ; 

 there, changing their route, and now in couples, they 

 spawn along the Sicilian coasts. In the Mediterranean 

 the fry of the sardine, known as poutina, is taken at Nice 

 a few fathoms from the beach. Thus the critical phases 

 in the life of the fish spawning, birth, growth, " fatten- 

 ing" occur near the coast. Spawning is a compli- 

 cated action which reacts upon every organ of the 

 animal. Many fish change their colour and appearance 

 at this time. The males in some cases develop a crest. 

 The Coitus scorpius and the tetrodonta secrete poison. 

 The salmon become quarrelsome and thin, and, like the 

 sardines, " go off their feed." These are sure signs of a 



