232 Fish Behavior and Angling 



Meredosia Bay ( Illinois ) were caught during the day and 69 per cent at 

 night. By comparison 11 per cent of the black crappies were caught 

 during the day and 89 per cent at night. "Night" included dusk, darkness 

 and dawn. 



Responses to Specific Stimuli 



Many instances of fish activity resulting from a combination of stimuli 

 have been recorded in fishery literature. Eschmeyer -^ found that when 

 the fall drawdown of Norris Reservoir was begun in September ( 1942 ) , 

 the white bass, yellow bass, and sauger migrated upstream from Watts 

 Bar Reservoir into the mouth of the Clinch River and upstream to 

 Norris Dam. These fishes represented the larger individuals of the 1942 

 year class ( the first ) produced in Watts Bar Reservoir. The distance from 

 Watts Bar Dam to Norris Dam is about 118 miles by water (river channel, 

 38 miles to the mouth of the Clinch and about 80 miles up the Clinch), 

 and several weeks elapsed after the drawdown was begun before these 

 fishes appeared below Norris Dam. Apparently the stimulus for this 

 unusual migration was the arrival of cooler water at Watts Bar Reser- 

 voir. Later on largemouth bass appeared in considerable numbers. A few 

 largemouth bass were present in the river between the reservoirs, but 

 white bass, yellow bass and saugers were relatively scarce. 



Fishes are sometimes stimulated to move by violent storms or in spring 

 by the entrance of warm surface water into cold ponds or lakes. For 

 example, wing nets set on March 9, 1942, in Fork Lake ( Illinois ) caught 

 few fish until a warm rain of about 1 inch fell during the night of 

 March 16. When this water drained into the pond, the fish were stimulated 

 to move and when the wing nets were raised on March 17, they con- 

 tained many more than the March "quota" of bluegills and some were 

 released."^ 



Wood ^^^ assigns to Dr. CM. Tarzwell the observation that largemouth 

 bass move into newly-flooded backwater areas with rising waters in less 

 than 48 hours after flooding has begun and are the first to leave when 

 waters begin to fall. 



Whitmore, Warren, and Doudoroff ^^ used a "channeled avoidance 

 tank" to test the reaction of small largemouth bass, bluegills, and several 

 kinds of juvenile salmon to various levels of oxygen tension. Marked 

 avoidance of 1.5 mg/1 dissolved oxygen was observed in tests of large- 

 mouth bass and some avoidance reaction was evident even with dissolved 

 oxygen as high as 4.5 mg/1. In bluegills avoidance reactions were definite 

 at oxygen concentrations of about 1.5 and 3.0 mg/1, although the latter 

 was not very pronounced. These experiments furnish proof that warm- 

 water fishes are capable of adjusting their movements to avoid low con- 



