62 FRESH-WATER BIOLOGY 



lecting seine, but seines of this form are expensive and not abso- 

 lutely necessary. 



Seines can be used only where the bottom is free from large 

 stones or deadwood and the water not much obstructed by vegeta- 

 tion. A brail, or stout pole, is fastened by a double half-hitch to 

 both cork and lead lines at each end of the seine so as to extend 

 from the cork line to the lead line and keep the seine stretched 

 between the two lines. The seine is then operated by two persons 

 each of whom holds a brail in such a way that the lead line is kept 

 close to the bottom which it sweeps, while the seine forms an arc 

 of a circle between the two brails. At the end of the haul the 

 seine is best landed on a gently sloping bank by seizing the lead 

 line and drawing it in first to the bank. Where the bank does 

 not afford a suitable landing place a short seine may be ''tripped" 

 in any depth of water by quickly pulling up the lead line until it 

 lies in the same horizontal plane as the cork line. The seine sag- 

 ging between the two lines retains the fish. A short seine may be 

 thrown or cast from a boat in deep water and immediately drawn 

 in and tripped. Small surface-swimming fishes are caught in this 

 way. Where a long seine is to be used in water too deep to wade, 

 a heavy weight is attached to the lower end of one brail so as 

 to keep it upright in the water. To the same brail a short rope 

 is so fastened that it extends loosely from one end of the brail 

 to the other. To the middle of this short rope, or bridle, is 

 attached a long hauling rope. The end of the seine is then 

 carried out into deep water by means of a boat and the free 

 end of the hauling rope brought back to shore, from which the 

 seine is hauled in by means of the rope. If a hauling rope and 

 weight are attached to each brail the seine may be set in the water 

 at any convenient distance from shore and parallel to it and may 

 then be hauled to shore by means of the ropes. 



(b) Trammel nets consist of one web of fine twine of about one 

 inch mesh between two webs of coarse twine of about six inches 

 mesh. A length of one hundred feet and a depth of six or eight 

 feet is convenient. The fine-meshed web is much deeper than 

 the coarser ones and all three are attached between a single 

 cork line and a single lead line. The net is "laid" in a boat 



