248 FISH HATCHERY MANAGEMENT 



The amounts to feed would be: 



July 1-8; 2.91% X 4,160= 121 pounds/day 



July 9-16; 3.13% x 4,160= 130 pounds/day 



July 17-24; 3.34% x 4,160 = 139 pounds/day 



July 25-31; 3.57% x 4,160= 149 pounds/day 



Under normal conditions, adjusting feeding levels four times during the 

 month should prevent over- or under- feeding. The advantage of this 

 method is its simplicity. 



Feeding Guides for Coolwater Fishes 



For many years, fish culture was classified into two major groups. "Coldwa- 

 ter" hatcheries cultured trout and salmon, and "warmwater" hatcheries cul- 

 tured any fish not a salmonid. Muskellunge, northern pike, walleye, and 

 yellow perch prefer temperatures warmer than those suited for trout, but 

 colder than those water temperatures most favorable for bass and catfish. 

 The term "coolwater species" has gained general acceptance in referring to 

 this intermediate group. 



Pond culture traditionally has been used to rear coolwater species. This 

 method of extensive culture involves providing sufficient quantities of 

 micro-organisms and plankton as natural foods through pond fertilization 

 programs. If larger fingerlings are to be reared the fry are transferred, when 

 they reach approximately 1.5 inches in length, to growing ponds where 

 minnows are provided for food. A major problem in extensive pond culture 

 is that the fish culturist is unable to control the food supply, diseases, or 

 other factors. Many times it is extremely difficult to determine the health 

 and growth of fish in a pond. 



In recent years the intensive culture of coolwater fishes in tanks has 

 been successful. Zooplankton, primarily Daphnia, are cultured in ponds and 

 each day a supply is placed in the rearing tanks. Fish reared in tanks can 

 be observed readily and treated for parasites. Fish also can be graded to 

 size to minimize cannibalism and to provide an accurate inventory. 

 Pennsylvania fisheries workers successfully fed a diet of lOO'Si Daphnia to 

 muskellunge for up to 5 months with no significant mortality, but after the 

 fish attained a length of approximately 2 inches the Daphnia diet did not 

 appear adequate. 



Fisheries workers in Pennsylvania and Michigan have reared coolwater 

 fishes successfully on dry feed. The W-7 dry feed formulated by the Unit- 

 ed States Fish and Wildlife Service specifically for coolwater fishes has 

 given the best results. (See Appendix F for diet formulation.) Starter feed 



