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FISH HATCHERY MANAGEMENT 





Figure 33. Marketable size catfish being graded and harvested from a large 

 earthen pond (Fish Farming Experimental Station, Stuttgart, Arkansas). 



because this increases loss to predators and the possibility of disease. 

 Crowding and the lack of food also will reduce the ability of small fish to 

 withstand handling stress. A fresh supply of water should be provided 

 while the fish are confined to the collection basin. 



Although harvesting the fish crop by draining the pond has the major 

 advantage of removing the entire crop in a relatively short time, trapping is 

 another popular harvesting technique. The advantages associated with trap- 

 ping include better overall condition of the fish, because they are collected 

 in silt-free water; reduced injury, because the fish are handled in small 

 numbers; avoidance of pond draining; successful harvesting in vegetated 

 ponds; avoidance of nuisance organisms such as tadpoles and crayfish; and 

 reduced labor, as one person can operate a trap successfully. The major 

 disadvantage to trapping is it does not supply a reliably large specified 

 number of fish on a given date. 



The most widely used trap on warmwater fish hatcheries is the V-trap 

 (Figure 35). Successful trapping requires knowledge of the habits of the 

 fish and proper positioning of the device. The trap usually is used in com- 

 bination with pond draining; it is positioned in front of the outlet screens 

 and held away from them, against the water current, by legs or some other 

 means. The trap is constructed so it floats with about 10% above the water 



