114 FISH HATCHERY MANAGEMENT 



fish. Most of the desirable crustacean species will repopulate the pond in 

 two or three days. 



Most members of the aquatic insect groups Coleoptera (beetles) and 

 Hemiptera (bugs) prey on other insects and small fish. In some cases, 

 members of the order Odonata (dragonflies) cause similar problems. Most 

 of these insects breath air, and can be controlled by applying a mixture of 

 one quart motor oil and two to four gallons diesel fuel per surface acre 

 over the pond. As insects surface, their breathing apertures become clogged 

 with oil and they may get caught in the surface film. The treatment is 

 harmless to fish but supplemental feeding should be discontinued until the 

 film has dissipated. Nonsurfacing insects can be killed by 0.25 part per mil- 

 lion masoten. 



Large numbers of crayfish in rearing ponds may consume feed intended 

 for the fish, inhibit feeding activity, cause increased turbidity, and interfere 

 with seining, harvesting, and sorting of fish. Baytex is an effective control; 

 0.1-0.25 part per million Baytex will kill most crayfish species in 48 hours 

 or less without harming the fish. 



Vertebrates that prey on fish may cause serious problems for the pond- 

 fish culturist. Birds, otters, alligators, and turtles, to name a few, are impli- 

 cated annually. Some can be shot, although killing of furbearing mammals 

 generally requires a special license or permit issued by the states. Fences 

 can keep out some potential predators, but nonlethal bird control (several 

 forms of scaring them away) do not produce long-lasting results. 



Adult and immature frogs have long plagued the warmwater culturist. 

 The adults are predaceous and may transmit fish diseases; the immature 

 frogs consume feed intended for fish and must be removed by hand from 

 fish lots awaiting transport. Adults usually are controlled with firearms, 

 whereas attempts to control the young are limited to physical removal of 

 egg masses from ponds or by treating individual masses with copper sulfate 

 or pon's green. Although some laboratory success has been achieved with 

 formalin, there still is no good chemical control available for frog tadpoles. 



Recordkeeping 



Factors to be Considered 



Recordkeeping, in any business or organization, is an integral part of the 

 system. It is the means by which we measure and balance the input and 

 output, evaluate efficiency, and plan future operations. 



Listed below are factors that should be considered in efficient record- 

 keeping. These factors are particularly applicable to trout and salmon 

 hatcheries, but many of them pertain to warmwater hatcheries as well. 



