American Fisheries Society 87 



For food for yearlings it is possible to produce in quantities 

 artificially and introclnce into the ponds a Avhole list of other 

 living creatures. 



In the first rank stands the artificial production of iiy-larvae. 

 These are produced most simply by setting on a stake about 20 

 inches above the water, a box open on the under side and having 

 a wire-cloth bottom 3 or 4 inches from its lower edge. On this 

 bottom are laid offal, pieces of dead animals or any kind of 

 carrion; the flies are attracted by the smell and come and lay 

 their eggs here, and the larvae, as they develop, fall into the 

 water and are eagerly taken by the fish. In producing maggots 

 in this way care must be used lest on warm days too many de- 

 velop, while on cold ones, the production may cease altogether. 

 In the first case, if more maggots are produced than the fish can 

 consume, the maggot-yielding meat must be taken out of the 

 box for a while. To lessen the smell nuisance, it is well to have 

 the maggot-box tight, with only small holes to admit the flies. 



In rearing yearlings, the artificial production of daphnid,5 

 and shrimps (Gammarus), which we have already considered, in 

 this paper, plays an important part; for, as the best period of 

 growth for yearlings is in summer, so also, because of the tem- 

 perature then prevailing, that is the fittest time to acquire a largo 

 quantity of daphnids in the ditches where they are produced. 

 In summer, too, the drains and small pools and ponds in the 

 fields generally yield a rich booty of these creatures. 



The above-named food creatures, which live and increase in 

 the fish-ponds them.selves, are unfortunately not everywhere to be 

 had in sufficient numbers. In particular, many salmon estab- 

 lishments located in wild situations are so poorly supplied with 

 natural food that it is necessary to furnish other food in the 

 ponds. The same necessity exists also in most establishments 

 which undertake the production of large numbers of yearlings in 

 small space, even when the situation would otherwise be favor- 

 able, — that is, when the stock is too great for the rich, natural, 

 food supply. In such cases artificial food must be provided. Of 

 the artificial foods to be considered for the rearing of yearlings, 

 are naturally to be mentioned all those which have already been 

 named in connection with fry-rearing; but it must be remarked 

 that spleen, liver and brain, which in themselves would be use- 



