54 



REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



assumes its fuuctious and rouses the desire for food. Until this time, 

 intent only on liidiny, the fry have clung obstinately to the bottom and 

 to the dark corners, but now they scatter about through the water, 

 with lieads upstream watching for prey. This indicates that they 

 must be fed. During this period of his growth it is simply necessary 

 to see that the young lish has plenty of water, that there is no hole or 

 crevice into which lie can be drawn by the current, and that he is pro- 

 tected from enemies, such as large fishes, minks, rats, kingfishers, and 

 herons. If not in a house, well-fitting covers must be provided to the 

 troughs and impassable screens command both ends. The screens are 

 of fine wire-cloth, 13 or 14 meshes to the linear inch, and present a sur- 

 face of 14 square inches to each gallon of water passing through them 

 each minute. Thus, if there are 4 gallons of water passing through the 

 trough each minute the portion of the screen beneath the surface of the 

 water must measure as mucli as 56 square inches, and if the screen is 

 12 inches wide the water must be 4f inches deep on the screen. 



Atlantic Salmou, rcieiiily hatched. 

 BEARING. 



The leading feature of the work of the station is the rearing of fry to 

 the age of six or eight mouths. The fishes reared are mainly Atlantic 

 salmon, but landlocked salmon, American brook trout, European brook 

 trout, rainbow trout, steelhead trout, American lake troi^t, Swiss lake 

 trout, Scotch sea trout, and saibling have also been handled. The fish 

 are fed wholly on artificial food from about June 1 till October or 

 November, when they are mostly liberated. To a limited extent they 

 are kept in artificial ponds, but troughs of the same form and dimen- 

 sions as those already described for use in developing the eggs and in 

 hatching have given satisfactory results and have been adopted for the 

 most part. Each trough is provided with a changeable outlet screen 

 and below the screen discharges the water through a hole in the bottom, 

 into which is fitted a hollow plug, the height of which determines the 

 depth of Avater in the trough. The hollow plug plays an important part 

 in the daily cleaning of the trough, which will be referred to further on. 



The use of the troughs in the open air, which, in the absence of com- 

 modious buildings, is a necessity, compels the constant use of covers to 

 keej) out vermin ; and wooden covers in pairs, running the whole length 



