84 Thiriy-sixth Annual Meeting 



full-grown iiiii|)lii])()(ls are beiior fitted for the (ini^vi-liiios and 

 yearlings. 



There are establishments that have engaged in this kind of 

 ampliipod culture on a large scale and feed all their fi-v and even 

 their yearlings exclusively on amphipods. \\'hcivv('r. in the 

 neighborhood of a hatchery there are natural ditches with cur- 

 rents of cool water, there are usually, under natural conditions, 

 so many amphipods that it pays to search them well as tlie 

 trout-brooks, for food for fry. 



However, the construction of such breeding-ditches is not 

 everywhere practicable, and the hunting up and the straining 

 ai-e time-consuming and fussy operations. Much as amphij^od 

 culture is to be recommended, however, one will, alas, gener- 

 ally fail of success for the reasons named. 



Eeally more dependent on external conditions than amphi- 

 ]iod-culture is the breeding of daphnids and copepods. thos'> 

 minute, almost microscopic Crustacea which in point of size 

 would be especially fitted for consumption by young fr}'. These 

 creatures occur naturally in trout-brooks only in small numbers, 

 since they in general demand a higher temperature. They are 

 plenty in our waters only during the warm season of the year an(l 

 they reproduce abundantly only at that season, passing the cold 

 winter months mostly in a state of rest. 



The only exceptions to this rule are in the cases of large, 

 deep lakes that do not freeze over in winter, where the species 

 named are to be found the whole year thru; altho, even here, 

 they occur very sparingly in winter. "Whoever is fortunate 

 enough to live in the vicinity of such lakes can at any time get 

 these animals for fry-food, by fishing with a fine gauze net. The 

 best time is in the twilight, say about an hour after sunset; for 

 the Crustacea mentioned have the habit of collecting in swarms 

 at the surface of the water at nightfall, whilst during the day- 

 time they scatter in the depths. Catches made in the twilight 

 are therefore far better. In lakes that freeze over in winter one 

 can count on a good catch only from May on, that is, when it is 

 for the most part too late for the rearing of f 17. 



The artificial culture of daphnids and copepods has been 

 often practiced. The process consists in laying out small ponds 

 of ahout 2 square meters, (22 square feet) and one-half or two- 



