HATCHERY OPERATIONS 



87 



surface and 90% below. As the pond is drained the trap simply falls with 

 the water level. Fish are attracted to the outlet screen for a number of rea- 

 sons, the two main ones being the water current and the abundance of food 

 organisms that are funneled there. Some species of fish are attracted to 

 fresh cool water, and a small stream of this should be introduced near the 

 trapping area if possible. The fish attracted to the area have to swim 

 against the outgoing current to keep from being pulled against the outlet 

 screen. They rest behind a glass plate that shields them from the current; 

 following this glass they come into the trap, from which they can periodi- 

 cally be harvested with a small net. 



The trap is used in another manner for harvesting small fish. The 

 advanced fry and early fingerlings of many species, such as largemouth 

 bass, smallmouth bass, and walleye run the shoreline of ponds in schools of 

 varying numbers. To collect them, the trap is fixed far enough out in the 

 pond that the fry swim between it and the shore. A wire screen lead run- 

 ning from the mouth of the trap to the shore, and extending from the 

 water surface to the pond bottom, intercepts the fish. As they attempt to 

 get around the lead, the fish follow it toward deep water and into the trap. 

 Four such traps set around a pond have caught up to 80% of the available 

 largemouth bass fry. 



Figure 34. Removing fish from a collection basin in an earthen pond. 



