14 4 American Fisheries Society 



Location The situation of the pond as to the ease or 

 a mT,Z of access from railroad stations or nearest vil- 

 lf es as we^a the hotel and boating facilities were 

 receded fir use in future shipment of fry or fingerlmgs, 

 or,^ »« a source of information to fishermen. 

 ™\rea No actual survey of the area of the ponds was 

 made, the size being measured from maps or taken fiom 



^Devthand bottom. Soundings were so made that the 

 contour lines, giving the depths, could be charted on dia- 

 grams of the ponds, and from these measurements, the 

 average and maximum depths were ascertained^ The 

 sounding lead was equipped to take samples of the bot- 

 tom soil but, unfortunately, on hard or mossy bottom 

 no soil could be gathered by this method, and the nature 

 of the bottom could only be estimated in shallow water 

 or from the character of the shores. 



Water The color of the water was listed as either 

 clear, green or brown. The turbidity was expressed in 

 feet, the number representing the distance below the 

 surface at which a white four-inch circular disc would 

 disappear from view. By means of a maximum and mini- 

 mum thermometer the temperature at the bottom was 

 taken in various parts of the pond to determine the pres- 

 ence of springs. In the deepest part a series of readings 

 were taken at intervals from two and a half to five feet 

 to determine the thermocline (described by Dr. b. A. 

 Birge of Wisconsin), or point where the temperature 

 drops rapidly. Deep ponds have three layers of water- 

 a surface layer, in which the temperature to a depth 01 

 fifteen to twenty feet remains approximately the same as 

 at the surface; a middle layer, or thermocline, in which 

 there is a rapid fall, and a bottom layer of uniformly low 

 temperature. The extent and nature of these three layers, 

 which vary in different ponds and at different seasons of 

 the year, are of importance as regards fish life from the 

 standpoint of food and oxygen. 



Shores. The shores around the pond were classified 

 as woodland, the kinds of trees being noted, and whether 



