Fish Hatchery Management - fisheries & aquaculture

106 FrsH HAT CHF,Ry NIA\AcE1\'rE\'lTABLE 14. IItiRBICTTDES RFrc;rsTF,Rr:D B\' 'r'HI UNr.r'l.D S t.r'r'Est()()t) .\\t) t)Rl-t(;AL. l1)7(i: SNOW lll At.. l1)(i.t.l\t.(;t.1.\ll()\I0\ICII\I0ct( )Nt P() U N I)r'()t{}11 L.\ I l()N",\l IL( il.1),\\llt.\1.5Coppersulfatt-Cr-vstals, I00 'Aluae and subnrcrgeclrootcd plantsModeratc to highDiquat(bromide)Endothall.iquid, il5',Liquid, i35"Enrerqent, terrestrial,su b m ergedSubmerged, rootecll,ot[,o*Si m azinePou der, liOAlgae, subncrgcd,tcrrestrial[,ou2,4,D'Granular, l0salt, ll0'ester, l]7 12'amine,2l'l-.12'granular, 20'I loating, emerqent,terrestria Il,ou or modcraleol'ercentages are percent actual ingredient.'Consult product labels for limitations on use.'Only for use b1' federal, state, and local public agencies.fish to a depth of two to three times the secchi disk visibility. Penetrationof oxygen below this depth depends on mechanical mixing.Two processes use up dissolved oxygen: chemical oxidation and respiration.Both occur throughout the water column and in the top layer of pondsediments. The first involves chiefly inorganic compounds and elements,and rarely is of major significance in ponds. Respiration is the main causeof oxygen depletion. All aquatic organisms respire - not only fish, butplants, phytoplankton (even during photosynthesis), zooplankton, bottomanimals (such as crayfish), and perhaps most importantly, the bacteria thatlive off nitrogenous and organic material'Over the whole year, but especially during the growing season, the oxygenconcentration in a pond is determined primarily by the balance of photosynthesisand respiration. For pond fish culture to succeed, photosynthesismust stay ahead of respiration. Pond management techniques involvemanipulation of both comPonents.Of all the physical variables that affect dissolved oxygen concentrations,temperature is by far the most important. It has direct influences on theoxygen balance: photosynthesis, respiration, and chemical oxidation allproceed faster at higher temperatures. It has a direct influence on a pond's