Behavior Patterns 233 



centrations of dissolved oxygen in tlie aquatie habitat. Pearse and Acbten- 

 berg '^ were able to show that perch \\'ould enter deep stagnant waters 

 of Lake Mendota where dissolved oxygen was very low. 



Hyperactivity as a Lethal Factor 



Under certain conditions death may follow violent muscular activity, 

 such as struggling of fishes in a live box, responding to vigorous chasing, 

 swimming through swift passages of water, or struggling on a trolling 

 line.^*^' While death from exertion is more characteristic of trouts and 

 salmon than of warm-water fishes, it mav occur in certain of the more 

 sensitive warm-water fishes such as gizzard shad, some minnows, and 

 occasionally smallmouth bass. 



The precise cause of death is unknown, but it is likely that the main 

 cause is a severe acid-base disturbance following a large accumulation 

 of lactic acid. The acid concentration becomes great enough to reduce the 

 oxygen-combining power of the blood, reduce its alkali reserve or carbon 

 dioxide-combining capacity, and alter the shape and probably the volume 

 of the red cells. 



Mortalities of fishes resulting from hyperactivity during handling and 

 transportation might contribute to oxygen deficiencies in holding basins 

 and tank trucks. This precludes the value of a tranquilizer in reducing 

 oxygen requirements during fish-moving operations. 



"Stay at Home" Fish 



Bass were reported to rove over the entire water area of Third Sister 

 Lake (Michigan) and showed almost no tendency to remain in one 

 location.^ In contrast some other fishes showed strong tendencies to 

 remain within a very small area. About 60 per cent of tag returns for 

 bluegills were taken within 30 yards of the point of original capture.'' Tlie 

 same was true of bullheads where 39 per cent were recaptured within 15 

 yards of the point of release and 81 per cent within 100 yards. In other 

 tests all of the bullheads recaptured more than once were taken at the 

 same location each time, even though the time intervals between re- 

 captures were several weeks or months.'''* Walleyes in Gogebic Lake 

 (Michigan) remained close to the original point of capture during and 

 after the spawning season; in fact 115 marked walleyes were retaken in 

 the same net in which they were originally captured.^^ Walleyes may be 

 less restricted in their movements later in the season, although fishermen 

 have discovered that these fish are often found in about the same locations 

 day after day. 



Newly-stocked fish may or may not move about, depending on the kind 

 of fish and various other factors. Smallmouth bass (from ponds) stocked 



