Table 1. — Summary of sampling by gill nets during Periods I to III and by trawl and gill nets 



during Period IV, Mayfield Reservoir 



Gill nets were fished for 18 hours (2:00 p.m. 

 to 8:00 a.m.); they were retrieved in the exact 

 order in which they were set to equalize fish- 

 ing time for all nets. After removal from the 

 water, each net was placed in a separate plas- 

 tic bucket that was marked to correspond with 

 the fishing position. When all the nets were 

 hauled, they were taken ashore and individually 

 stretched across railings to permit examina- 

 tion of the catch and to determine the direction 

 from which the fish entered the nets. 



Turbidity was measured each operational 

 day at three positions across the experimental 



site. Secchi disc readings ranged from 0.15 m. 

 to 5.2 m. and averaged 1.9 m. 



Water temperature was measured each 

 morning at each fishing station before the net 

 was removed from the water. Temperature 

 ranged from 0.5 to 20° C. (average 8.9° C.) at 

 the surface (0 to 11.0 m.); 3.3 to 14.4° C. 

 (average 8.3° C.) at middepth (1 1.0 to 21.9 m.); 

 and 7.2 to 12.2° C. (average 8.3° C.) at the 

 bottom (below 21.9 m.). 



The trawl was pulled between two boats 

 along courses that were marked with buoys 

 fitted with flashing lights to permit fishing 



