IGG 



BULLETIN OF THE BUREAU OF FISHERIES. 



lirt'enhack iroui {Sahuo stomias). — The stoniaclis of 7^ i^'rcenback trout were 

 cxuiiiiiK'd. Eight of them were empty, leavintf 64 to be aci'ounted for in the talile. 

 Of tliis number, 18 were obtained from Upper Lake, 1 from Lower Lake, and 53 

 from the pool below the dam. 



Contents of stomachs of 64 greenback trout. 



Food elcmouts. 



Fish remaiiiH 



OrtliopttTii 



Ht'inipti'Di 



TricliopttTii 



Lopidoptera (moths) 

 Diptera 



Number 

 of speci- 

 mens 

 in which 

 found. 



Average 

 per cent 



of 

 element. 



70.0 

 .W.7 

 fi. 

 10.0 

 42.0 

 30.8 



Food elements. 



Chironomus (larvae and pupaO 



Col eoptera 



Hymen(H)tera (ants) 



Insect f rag^ments 



Crustacea (Entomostraca) 



Vegetable di^'bris 



Number 

 of .speci- 

 mens 

 in which 

 found. 



Average 

 per ceut 



of 

 element. 



17.75 



42.7 



19.4 



51.7 



77.0 



38.4 



Specimens from all three localities contained Daphnid. One stomach contained 

 4,5(H) 7A(j(^/</(/ff and another 2,250. Two of the specimens had eaten ))oth copepods 

 and Daplmia, but the other 12 of the l-l that had eaten Entomostraca contained 

 Daphiiiii onl}'. 



The vegetable debris con.sisted chiefly of I'otdiiiiigeton leaves. 



A feather was found in one stomach and a few pieces of twine in another. 



Jordan (1891) says, concemiug the food of this species: "At the hatchery of 

 Dr. Laws, it appears that this trout will not willingly eat young suckers and 

 minnows, its food being largel_y .young crustacea." It will be noted in the above 

 table that only 1 stomachs out of 64 contained remains of lishes. 



Ridiihoio front {Salmo irldeiix shmta). — The stomachs of ll-f rainliow trout were 

 e-\aniined. Out of this number 8 were empty, 36 were estimated to l)e a third full 

 or more, and the other 70 a cpiarter full or less. The specimens varied in length 

 from 6 to 18 inches (15 to 45 centimeters). Twenty-two of them were caught in 

 Upper Lake, 24 in Lower, and 68 in the pool below the dam in the outlet canal. 



Contents of stomaclis of 106 rainlmir trout. 



Food elements. 



Mammal remains . . . 



Fish remains 



Araueida (spiders) . . 



Odonata 



Ortlioptera 



Hemiptera 



Trichoptera 



Lepidoi>tera (moths) 

 Diptera 



Number 

 of speci- 

 mens 

 in which 

 found. 



Average 

 per cent 



of 

 element. 



42.0 

 67.3 

 10.0 

 2.5 

 4.3 

 2.6 

 4.7 

 13.6 

 8.9 



Food clemeut; 



Chironomus (larvae and pup*) 



Simulium (larva?) 



Coleopiera 



Hymenoptera 



Insect fragments 



Crustacea 



Mollusca 



Vegetable debris 



Sand and gravel 



Number 

 of sped- 1 



mens 

 in which 



found. 



Average 

 per cent 



of 

 element. 



10.3 

 68.3 

 22.2 

 5.6 

 5.5.1 

 37.3 

 40.0 

 35.6 

 41.8 



About a fourth of the Hsh remains were positively identitied as remains of young 

 suckers ((!'. co//uiie/:'<oiii,i) Imt the rest wqvg not recognizable. These results do not 

 agree with the observations of Chambers (1887), who states that the rainbow trout 

 introduced into England "is more delicate in its appetite than other varieties of Sal- 

 monidie. and therefore is not prone to the same temptations to caimiljalistic attacks 



