172 SEA FISHERIES 



Altona, some 540 tons of assimilable alimentary matter. 

 The animal plankton in its turn fed upon this prey : 

 assimilated it, developed, and multiplied itself in dense, 

 thick layers. Small crustaceans and rotifers abounded. 

 The table being served, the places were quickly taken by 

 fishes of all species. There was an invasion of flat-fish, 

 soles, plaice, flounders, dabs, turbot, and especially of 

 brill. Their abundance was so great that many 

 perished in the struggle for life. 



Ill 



The dependence, direct and indirect, of the edible 

 fishes upon their ocean environment is sufficiently 

 obvious ; but where does it begin and where end ? In 

 other words, how does the fish " strike the balance " with 

 its environment ? This is a very difficult question, to 

 which we can only give an apology for an answer. 



The employment of the facile criterion of temperature, 

 and perhaps a desire to justify it, has resulted in the 

 introduction of narrow and exclusive ideas into science. 

 According to these ideas, a given species cannot disport 

 itself until the thermometer marks a given degree. The 

 truth is not so simple. Fish can support great differences 

 of temperature. Sardines are supposed to be extremely 

 delicate ; yet they have been found in the Bay of 

 Biscay in midwinter, when the surface water was 

 at 50, testifying an evident appetite for rogue. The 

 fishers of Arcachon lose no opportunity of catching 

 them, although they have to light fires on their boats 

 to thaw their nets. M. Camille Mader is therefore 

 absolutely in the right when he says that " excessive cold 

 does not cause the exodus of the sardine, and does not 

 prevent a few shoals or individuals becoming temporarily 

 pelagic, despite the lowered temperature of the surface of 



