V THE INTERNATIONAL FISHERIES EXHIBITION 205 



the natural balance is upset, and chiefly in so far as 

 the j)roduction of young fish is concerned. It is true 

 that several thousand young are produced by each 

 pair of fish left in the breeding area, and it might be 

 argued that since, in the absence of man, only two 

 out of the many thousand born of each pair of fish 

 come to maturity and breed again in their turn, the 

 only result of man's depredations (in addition to the 

 depredations of other enemies) is to make way for 

 more of the young, and to enable more than two of 

 the many thousands born of each pair in a preceding 

 generation to survive and breed in their turn. This 

 argument is at once seen to be fallacious when we 

 remember that the thousands of apparently superflu- 

 ous young produced by fishes are not really superfluous, 

 but have a perfectly definite place in the complex 

 interaction of the living beings within their area. 

 These very young fish serve as food to other forms, 

 which in their turn are fed upon by others, and are so 

 interwoven with the necessities and conditions of life 

 of other inhabitants of the area, that to remove, say 

 something like a fifth or even a tenth of them by 

 removing the parent fish, must cause a serious dis- 

 turbance in the vital balance of that area. When 

 the fisherman removes a large proportion of soles 

 from a given area, and so reduces the number of 

 young soles born in the same season in that area, he 

 does not simultaneously destroy the natural enemies 

 of the young soles : consequently very nearly the 

 same number of young soles are destroyed by such 

 natural enemies as were so destroyed before man inter- 



