Behavior Patterns 241 



In most small lakes and ponds fishing is poor it the transparency of the 

 water is less than two feet ( Secchi disk ) . Fly casting is probably best 

 when the transparency of the water ranges between 3.5 to 6.0 feet. When 

 the transparency is greater than 6.0 feet, fish are able to see the angler 

 for some distance and unless long casts are made to place the angler 

 bevond the fishes' vision, or extreme care is taken to shield his movements 

 from the fish, the rate of catch will decrease as the water becomes clearer. 



The late Professor W. P. Flint of the University of Illinois and the 

 Illinois Natural Historv Survev, trained the bluegills around his boat dock 

 at the Sunset CliflF Club Pond ( an abandoned stripmine where the water 

 was very clear), to feed upon bread crumbs tossed to them. He also 

 taught them to scatter when anyone appeared with a moving fly rod, and 

 he took great pleasure in demonstrating that although these fish behaved 

 like pets when being fed on bread, thev were nearly immune to fishing. 



Diurnal Effects. Alternate periods of darkness and daylight affect the 

 feeding and therefore the catch rate of fishes. Often diurnal movements 

 of certain species develop in certain lakes and these movments are usually 

 associated with feeding. Such movements ~^' -"^ have been described on 

 p. 231. 



It is impossible to sav that the stimulus for feeding is entirely one of 

 the changes in light intensity even though periods of feeding in many 

 lakes appear to be associated with dawn and dusk. 



Rising and Falling Water Levels. Most artificial lakes are built to store 

 water temporarily during heavy runoff from the watershed. This storage 

 capacity respresents the vertical distance within the lake basin between 

 a lower normal spillwav crest and a higher large surface floodway. Once 

 the lake level rises to the crest of the floodwav, several hours mav elapse 

 before the stored water has time to pass over the lower normal spillway 

 outlet to bring the lake back to "normal" level. This capacity for storage 

 reduces the size ( and cost ) of spillway structures and assures that sudden 

 rises in water level in the lake are common. The extent of these rises may 

 vary, but in most artificial lakes the range of vertical distance for storage 

 between the normal spillw ay crest and the flood spillway crest is from 

 1 to 6 feet. 



A sudden inflow of water mav stimulate fish to move and feed, par- 

 ticularly in earlv spring when runoff water from a warm rain may bring 

 in water at a temperature above that of the lake. Fish may feed actively 

 as long as silt brought in by the runoff does not cause the lake to become 

 turbid. 



Channel catfish are alwavs stimulated to feed on rising water levels; in 

 fact, it is almost the only time they bite well in lakes. 



Flood waters almost always carry a load of silt, and the fishes that 

 depend upon sight for feeding may have difficulty in finding food. This 



