WHITEFISH OF THE LAKE OF GENEVA 



and is disseminated through its whole mass, delight 

 our eyes and are utilized for our subsistence, placed 

 at our service by these intermediaries which Nature 

 has so well devised. We utilize them for our own 

 purposes. Common sense suggests that we should 

 see whether we cannot make better use of them, and 

 actually increase production. 



The Lake of Geneva is a limited area with a material 

 equilibrium of its own. The water brought by the 

 streams which flow into it and the water taken out 

 of it by the Rhone, together with the evaporation 

 which takes place, give it a fairly constant average 

 volume estimated at ninety-nine milliards of cubic 

 metres. It has an average balancing factor of vital popu- 

 lation. The capacity having limits, the maximum pos- 

 sible absorption of sunshine has corresponding limits. 

 Consequently, the direct maintenance of the micro- 

 scopic beings which form the first ring in the alimentary 

 chain is also constrained within certain limits. The 

 quantity of these creatures cannot exceed a definite 

 quota, and this quota is fixed by the very conditions 

 of the lake. Their number, their capacity for in- 

 creasing, are not limitless; they stop at a mark past 

 which they cannot go. The other rings in the chain 

 are affected by this first condition; they, too, cannot 

 go beyond the limits assigned to them. There are 

 thus natural limits to the total production of fish, and 

 these are laid down by the cycle of nutrition. Pro- 

 duction may fall below, but it can never rise above. 

 The quantity of the plankton, the mass upon which 

 the rest is maintained, is the governing factor. 



It is a more powerful and effective factor than it 

 seems. If the open water fishes, whitefish, char, 

 trout, depend entirely upon it; those of the shore 

 waters, and of the bottom, perch and pike, do the 

 same. The greater devour the smaller all through the 

 scale, feeding upon corpses or fragments, but the 

 smaller, who maintain the rest, find what is essential 



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