206 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



C7 — THE AMEKI€AIV BROOK TKOUT KECOill^IE.^DEI) FOK SWISS 



WATTE KS.* 



By HERMANN GOI.L. 



Tbaiilis to the eifortsoftlie German Fishery Association, it has become 

 possible to acclimatize in European waters several kinds of American 

 fish, such as the California salmon, the valuable American salmon trout 

 {Seclachu, lake salmon), the whitelish, and the American brook trout 

 {Balmo fontinalis Mitch.), t Von Clapardde in the spring of 1883 sent a 

 considerable number of the eggs of this fish to Switzerland ; 4,000 were 

 sent to the canton of Vaud, and were hatched in the small fish-cultural 

 establishment of Eoveray, near Allaman. Unfortunately the hatching 

 troughs were one day Hooded by violent showers, and in consequence a 

 large number of the young fish which had been hatched were carried 

 away. Of the small remnant, about 300 were placed in a pond near St. 

 Prex, and 100 in a small pond in my garden. This pond has a long oval 

 shape, and measures 4 meters in length, 2 in breadth, and almost i meter 

 in depth ; its walls are of cement. It is fed from my house reservoir, 

 containing good drinking water with but little lime in it, which comes 

 from the Pierre-Ozaire. The temperature of this water is 6.5 to 7° C. 

 [about 44° Fahr.] : in summer it exceptionally rises to 12^ [53.0° F.]. As 

 hidingplaces for the little fish, my pond has some small caverns of tufa, 

 forming a sort of subterranean i^assage. The bottom is covered with 

 mud from the lake, in which there is a dense growth of Elodea canadensis 

 and Fotamogeton densus. 



The young brook trout, which had been i>laced in the pond, in the be- 

 ginning persistently hid themselves, so that I began to doubt whether 

 they were really there. Some articles of food which were thrown into 

 the pond were not touched, aud I therefore stopped throwing in any food. 

 After about tliree njonths some of the little fish occasionally made their 

 a])pearance, having grown considerably. When i^laced in the pond, they 

 measured 18 to 20 millimeters [^ inch| in length, while now they meas- 

 ured 5 to C centimeters [2^ inches]. I now had frequent opportunities 

 to see of what their food principally consisted. My aquatic plants were 

 covered with great masses of Gammarus roeselii; and my little fish 

 eagerly chased small si)ecimens of this crustacean. 



In September, 1883, my fish measured '9 centimeters [3^ inches] in 

 length. To accelerate their growth, I placed in the pond a number of 

 small Fhoximis Iwvis, and several small specimens of Cdbitis barhaUda. 

 These fish all disappeared, and I presumed that the trout had devoured 



* " Der amerikanische Bach-Jiothel." Translated from the German by Herman Ja- 



COP.SOX. 



t In Jannary, 1883, 25,000 brook-trout eggs were scut by the United States Fisli Com- 

 mission to tlae Deutsche Fischerei-Vereiu. See F. C. Reiiort for 1883, p. xli. 



