Fish Hatchery Management - fisheries & aquaculture

HATCHERY OPERATIONSsupplemental feeding. Up to 2,000 pounds or more of fingerling fish peracre can be reared with supplemental feeding.If fish larger than 4 inches are desired, stocking rates must be reduced.Experimental evidence suggests that 1,500,3- to 6-inch fingerlings per acrewill produce l-pound fish in 180 days.HIGH-DENSITY CATFISH CULTURESpecialized catfish culture systems have received much publicity in recentyears, and several high-density methods are currently under investigation.These include the use of cages; earthen, metal, or concrete raceways; varioustank systems; and recirculation systems. High-densityfish culturedemands not only highly skilled and knowledgeable management but alsorequires provision of adequate amounts of oxygen, removal of wastes, and acomplete high-qualitydiet. The methods used for calculating carryingcapacity in salmonid hatcheries can readily be used for intensive culture ofcatfish.STRIPED BASSAt present, most striped bass rearing stations receive fry from outsidesources. Eggs are collected and usually hatched at facilities located nearnatural spawning sites on the Atlantic coast. Fry are transferred to thehatchery at I to 5 days of age. There they are either held in special tanksor stocked in ponds for rearing, depending on the age of the fry andwhether or not they have sufficiently developed mouth parts to allowfeeding.Earthen ponds are fertilized before stocking to produce an abundance ofzooplankton. In these prepared ponds, striped bass fry are stocked at a rateof 75,000 to 125,000 per acre. A stocking density of 100,000 fry per acre,under normal growing conditions, yields 2-inch fingerlings in 30 to 45days. Survival is very erratic with this species, and may vary from 0 to100% among ponds at the same hatchery. As with most pond-cultured fish,the growth rate of striped bass increases as the stocking density decreases.If a 3-inch fingerling is needed, the stocking density should be reduced to60,000 to 70,000 fry per acre.Culture of striped bass larger than 3 inches usually requires feeding formulatedfeeds. Striped bass larger than 2 inches readily adapt to formulatedfeeds, and once this has taken place most of the procedures of trout culturecan be applied.NOR'THERN PIKE AND WAI,LEYEThese coolwater species represent a transition between coldwater andwarmwater cultural methods. A combination of extensive and intensive