Fish Hatchery Management - fisheries & aquaculture

HAT( H[.R\ RF.QI rRt.l\lt..N l5',25microbial breakdown of waste feed, most of it comes from fish metabolism.The amount of metabolism, hence the amount of ammonia excreted, isconditioned by the amount of food fish eat. For each hatchery and feedtype, an ammonia factor can be calculated:ammonia f'actor-ppm total ammonia x gpm water inflowlbs food fed per dayHere, ppm is parts per million concentration, gpm is gallons per minuteflow, and lbs is pounds. To establish the ammonia factor, total ammoniashould be measured in raceways, tanks, and ponds several times over oneday. Once the factor is established, the formula can be turned around togive estimates of total ammonia:Ppmtotal ammonialbsfood/dav x ammonia factorgpm flowThen, by reference to Appendix B with the appropriate temperature andpH, the concentration of un-ionized ammonia can be estimated.Example: Three raceways in a series have a water flow of 200 gallonsper minute. Fish in the first raceway receive 10 pounds of food per day, 5pounds of feed per day go into the second raceway, and 20 pounds of feedper day go into the third. The ammonia factor for these raceways is l'].0. Inthe absence of any water treatment, what is the expected concentration oftotal ammonia nitrogen at the bottom of each raceway?Raceway ' l' +:g: o.l5 ppm200(10* 5) x gRaceway 2:U.ZJ DDm200(ro*s*zo) x 3Raceway 3::0.51i ppm200Treatment of Effluent Water and SludgeThe potential of hatchery effluent for polluting streams is very great. Likeany other source of waste water, hatcheries are subject to federal, state, andlocal regulations regarding pollution. The United States EnvironmentalProtection Agency requires permits of hatcheries that discharge effluentinto navigable streams or their tributaries. Hatchery operators are responsiblefor knowing the regulations that apply to their facilities. Some treatmentof hatchery effluent is required of almost every hatchery. This is trueeven for systems that recycle and treat water internally; their advantage