Fish Hatchery Management - fisheries & aquaculture

74 FISH HATCHERY MANAGEMENTTABLE IO. RECOMMENDED HATCHERY POND LOADINGS (POUNDS OF FISH PER GAL-LoN PER MINUTE, INFLOW), BASED ON DISEASE CONSIDERATIONS, FOR CHINOOKAND COHO SALMON HELD IN lJO X 2O.FOOT PONDS. THE VALUE,S REPRESENT FINALPOND OR RACEWAY LOADINGS A1' 'TIME OF RELEASE OR HARVEST FOR FISH SIZES OFlOOO }ISTI PER POUND AND LARGL,R, I,OADINGS SHOUI,D NOTEXCEEDTHE'IABLEVALLTE BEFORE TIME O!' REI,EASE, INFORMATION IS NOT AVAILABI,E FOR OTHER.I'EMPERAI'URES. SIZES, OR SPE,CIES O!' FISH. (SOURCE: WEDEMEYER AND WOOD I97'1.]WA I I,]R1'I,M PI'JRAl rrnrs ("F) 1,000 500FISH SIZ!] iNUMBER PI]R POI.'ND]100 33Coho salmonllu,1u5ll63(iuli.5'2.72.25.0'1.03.02.0u.0(;.0,+.53.51.5I 1.010.07.05.02.015.0 20.0 25.01,1.0 16.0 11J.010.0 12.0 15.07.0 9.0 10.03.0 ll.0 ,1.0l'all and spring chinook salmon3lJ,1u5u(ilI3.02.52.0,1.03.02.2t.26.05.0ll.53.08.06.5.1.53.5l 1.0 r2.0 13.09.0 10.0 l l.06.0 7.5 9.0.1.0 5.0 5.5their length have a density index equal to 0.5. A useful formula to avoidovercrowding raceways is:W:DXVXLWhere I,/ :Permissible weight of fishD : Density index (0.5 suggested for trout)I/ : Volume of raceway in cubic feetZ : Fish length in inchesRaceway or pond volume requirements can be calculated with the formula:V:W+(oxL).Volumes of circular tanks can be determined from Table C- I in AppendixC.This concept of space requirement assumes that the Density Indexremains constant as the fish increase in length. In reality, larger fish maybe able to tolerate higher densities in proportion to their length. Thismethod has proved to be a practical hatchery management tool, nonetheless,and can be used with any species of fish for which a Density Indexhas been determined.