182 Fortieth Annual Meeting 



young fish by the miUion, and throw them out by the 

 hundred thousand, into all the sorts of waters which their 

 species inhabit, without any precise knowledge on our part 

 of the conditions in which they will find themselves when 

 set free, or any rational judgment of the chance that they 

 can survive to adult size. This sort of thing, I surmise, 

 has sometimes been done, but I hope that it is, at any rate, 

 done no longer, and certainly it can no longer be defended 

 as either scientific or practical ; it is simply ignorant. In- 

 telligent plans for their improvement require that we should 

 know the conditions under which our fishes live, and that 

 we should be able to distinguish beneficial conditions from 

 injurious, and important conditions from unimportant. We 

 need to know what our fishes require in respect to the main 

 essentials of their well-being, that is, to a suitable water 

 supply, to oxygen for respiration, to temperature in the 

 different parts of the year, to their food at all their ages, to 

 breeding places, to freedom of migration and other neces- 

 sary movements to and fro, and to freedom from injurious 

 physical conditions, from poisonous gases and solutions, 

 from parasites, from diseases, from excessive competition, 

 especially for food, and from decimation by their enemies. 

 It is commonly conceded, I think, both by scientific 

 students and by practical fishermen, that the most general 

 and rigorous natural limitations upon the numbers of fishes 

 are those set by their breeding grounds and their food sup- 

 ply, and that of these the latter is the most important. We 

 especially need to know, therefore, what the more valuable 

 fishes feed upon as fry, as young, and when full grown, 

 under various conditions, and at different times of the 

 year; where their food supply is most abundant; whether 

 their most important food resources are at all times suffi- 

 ciently accessible to them, and under sufficiently favorable 

 conditions ; what their food species feed upon in turn ; and 

 so on down through the series of forms dependent one upon 

 another until we reach the primary sources of their food, 

 and the conditions of its greatest abundance and availability. 



