71 8 BULLETIN OF THE BUREAU OF FISHERIES. 



their efforts to escape some of the fish will be hung in the wire cloth, but it will 

 be noticed that every trout which gets its head through the screen can pass or 

 be assisted through without injury. The few which are caught in the mesh 

 should be assisted by grasping the tail and pushing them. It would be well 

 to refrain from feeding for about twenty-four hours before assorting the fish. 



By using two or three sets of screens in different troughs at the same time 

 one man can assort many thousands of fish in a day, and the sizes will be much 

 more uniform than when assorted with a scaff net. Wire cloth, 6 bars to the 

 inch each way, painted with asphaltum varnish, will permit all brook trout 

 under i inch in length to pass through. By varying the mesh of screens brook 

 trout may be assorted into six uniform sizes as follows : 



Number of bars to the inch: Size offish. 



6 All under i inch. 



5 All between i inch and i \4 inches. 



4 All between i ■ < and 2 inches. 



3 All between 2 and 2 5 s inches. 



2j\ All between 2^8 and 3 inches. 



2 All between 3 and 3H inches. 



The frames of these screens are made of half-inch wooden strips grooved 

 and tongued at the ends. These frames are one-eighth inch less in length than 

 the inside width of the troughs and in height equal the depth of the troughs, 

 being rectangular in form. They are covered on one side with wire cloth held 

 firmly by copper tacks, both the wire cloth and the frames being painted with 

 asphaltum varnish previous to tacking the wire on the frames. This not only 

 helps to preserve the "wood and keep the wire from rusting, but smooths the 

 latter so that there are no rough surfaces or projections to injure the fish as 

 they work their way through. 



ATLANTIC SALMON. 



Another important branch of fish culture is conducted at the Craig Brook 

 station, near the Penobscot River, not far from Bucksport, Me. While not 

 restricted in its work to this one species of fish, the primary object of this hatch- 

 ery is the propagation of the Atlantic salmon. The decadence of this important 

 fishery on the North Atlantic coast, due to the ruthless but natural progress 

 of civilization, is too well understood to call for an explanation here. Suffice 

 it to say that to-day the Bureau is maintaining a commercial fishery for the 

 Atlantic salmon on the Penobscot River purely by artificial propagation. It is 

 the only river in the United States where this once abundant salmon is now 

 found in sufficient numbers to support a fishery or to warrant its artificial 

 culture, and here, with the natural conditions so changed, it is with no little 

 difficulty that the extinction of the species is prevented. 



