214 Fish Behavior and Angling 



of the next most often listed color which was black. -^' -^ Among fly rod 

 lures, yellow seemed to be the color most acceptable to the largemouths; 

 white or combinations of white and other colors caught the second greatest 

 number of fish. Black lures were important in both casting and fly rod 

 sizes; some fishermen believe that fish strike black lures because they 

 see these baits poorly and strike out of curiosity. Black plugs that create 

 a disturbance at the waters' surface are often very effective for night 

 fishing. Fish swimming below such a surface lure at night follow the 

 water disturbance and may see the indefinite outline of the lure. 



Underwater observations of the behavior of smallmouth bass in a 

 quarry lake made by members of the Aquatic Biology staff of the Illinois 

 National History Survey supported the idea that colors of lures were im- 

 portant. Smallmouths lying in several feet of water along a steep bank 

 were presented with variously colored floating fly rod "poppers" of cork 

 and hair, by a fisherman operating from a boat. A diver equipped with 

 scuba * watched the behavior of fish as the "poppers" were moved over- 

 head. Red and yellow "poppers" obviously excited the fish and even when 

 they did not strike they often made short runs under the baits. They 

 were particularly excited by "gantron" baits (covered with paints having 

 high reflecting qualities ) in very bright yellow. Poppers of blues, greens, 

 white, and black apparently stimulated very little interest in these small- 

 mouths living in the clear quarry water. 



Underwater Vision 



A description of a fish's underwater vision is given by Walls ^^ as fol- 

 lows: "if a fish looks slantingly upward at the water surface, he cannot 

 see through it, but instead sees mirrored upon it objects which are on 

 the bottom at a distance (Figure 8.1). If he looks more directly upward, 

 he sees into the air. In effect there is a circular window in the surface 

 through which he can look. This window enlarges if he sinks, shrinks if 

 he rises, but always subtends an angle of 97.6° (in fresh water) at his 

 eyes (Figure 8.1B). If the bottom is distant, the surface outside the 

 window is silvery with the reflection of the light scattered in the water, 

 and this light of course always washes over and dilutes the image of the 

 bottom, even when the latter is close enough to the surface to be seen 

 reflected from it. 



"Through his surface window the fish sees everything from zenith to 

 horizon in all directions. This hemispherical aerial field is not narrowed 

 or widened according to the size of the window and depth of the fish. 

 It always contains everything above the plane tangent to the water surface 

 at the rim of the window, but the distortion and brightness of objects 



* Self-contained underwater breathing apparatus. 



