The Productivity of Fish Food in Oneida Lake ^y 



when the percentage of dry matter has been determined for the 

 dift'erent years, the number of individuals, as also the total 

 rough weight of the species for loo stations or more, will give 

 good information regarding the mass of the animal life per 

 square meter." 



" I am inclined to believe, that an evaluation with such 

 bottom- samplers could be carried out comparatively easily, and 

 would lead much further than plankton determinations alone 

 can, in the direction of the determination of the mass of fish 

 food. We may certainly with Hensen consider it a condito 

 sine qua non, that we must know on the main points the 

 capacity of a water as regards the production of fish-nourish- 

 ment, in order to be able to judge as to its rational exploitation 

 in the interest of the fisheries. It will, however, scarcely be 

 an easy matter to determine exactly, by quantitative investiga- 

 tion of the food animals alone, the quantity of food available 

 yearly, annual food-production, for the consumption of the 

 fishes or other animals in any water ; nor is it practically 

 possible in the case of the plankton; it is only the logical con- 

 sequence of our scientific mode of working to attempt to do 

 such a thing. Both Hensen and the present work endeavor 

 therefore at the same time to find another, more direct way, 

 namely, to determine the production of food by investigating, 

 what is actually used of the food by fishes or other animals 

 which have lived on this food. When we have determined in 

 this way, hoiv much a sea-bottom can produce, it is compara- 

 tively easy by means of the bottom-sampler to compare this 

 bottom with another and thus obtain a good insight into, 

 whether the one or the other is best suited for the production 

 of the one or the other kind of food-animals, this or that 

 species of fish, and whether on the whole it is more productive 

 than the other. It is this I have in mind in using the expres- 

 sion ' valuation of the bottom.' " 



Fish culturists and fishermen alike will agree that this is 

 sound logic and really goes to the bottom of the subject, for 

 until we have detailed knowledge of the life of a body of water, 

 including a fairly accurate estimation of the quantity of its 

 biota, we cannot intelligently begin the rearing of fish. In 



