VALUE OF NORWEGIAN LAKES FOR FISH CULTURE. 587 



little with the eggs which are placed in this basin as with those which 

 are placed in the apparatus especially constructed for hatching. But 

 he does not employ the basin for this purpose unless his hatching aj^pa- 

 ratus becomes too small to accommodate the whole quantity of eggs. 



The reservoirs which are to contain crawfish are entirely covered like 

 the stone troughs, and get the water directly from a spring and from 

 the river. It is highly amazing to see the enormous quantity which Mr. 

 Kiiffer has packed together in so small a space. In a division which is 

 not longer than 2^ meters and 1^ meters broad, there were heaped upon 

 one another more than 6,000 crawfish. They were so crowded that they 

 lay in many layers, one above another. They were remarkable for theii* 

 size and weight ; some weighed 250 grams and upwards. The males 

 are always separated from the females, and live in a reservoir by them- 

 selves. Notwithstanding the narrow space and the little care bestowed 

 upon them, only a very small number die. 



In an estabhshment at Salzburg, which is almost as small as Mr. Kiif- 

 fer's in Miincheu, fishes are fed with minced horse-flesh and the com- 

 moner kinds of fishes. They feed 30,000 large and small fishes, which 

 are in the establishment, at a daily expense of 44 cents. 



In Amsterdam, where a grand establishment is constructed for fish- 

 hatching, chiefly for stocking the rivers of Holland with salmonoid 

 fishes, in the winter of 1873 and 1874, from 250,000 impregnated eggs, 

 they got 238,000 living j'^oung ; the loss was under 5 per cent. All of 

 these were Hberated in the rivers Yssel and Vecht. With regard to 

 the increase of the abundance of fish in the larger rivers by means of 

 the hatching in this establishment during a few years, it is noticeable 

 that the state owns 38 fisheries, which are leased, the amount of whose 

 rental is quite considerable ; thus, for example, share i^To. 2, which be- 

 fore 1873 had been leased for 10,000 florins yearly, at the auction sale 

 of leases the same year was rented for 35,000 florins. Share No. 12, 

 for which previously was given 8,000 florins, was leased for 47,500 florins, 

 and so on. These figures speak for themselves; ujion the whole, the rent 

 is more than triple what it was earlier. 



As universally applicable results from the observations made, M. 

 Bouchon Brandely lays down as essential the following rules : 



The depth and extent of the reservoirs and basins ought to vary ac- 

 cording to the number and age of the fishes which are to live in them. 

 For trout of two to three years, is required a depth of 60 centimeters ; 

 for older trout, 1 meter. A greater depth will, of course, do no harm, 

 but that mentioned is sufficient. For the young, broad trenches of little 

 depth are better than reservoirs. The bottom should consist of small 

 stones with water-plants here and there, with the borders planted with 

 bushes, which hang out over the water, partly to give shade, partly to 

 supply nourishment, since quantities of insects and larvae will frequent 

 them and fall into the water, wUere they with greediness will be captured 

 by the young. The young of different species of fish, even belonging to 



