Fish Hatchery Management - fisheries & aquaculture

256 FISH HATcHERY MANAGEMENTTABLE 3I.INITIAL FEEDING TIMES FoR vARIoUS SPECIES oF FISHINITIALWATERFEEDINGTEMPERSPECIES(DAYS POST.HATcHINc)ATURE('F)REMARKSBrook troutZJ_JJ52Several fry had food in gut on23rd day; all fry were feedingon the 35th day.Brown trout3l52Evidence of food in stomach on27th dayl all fry feeding on 3lstduyCutthroat trout2347-51Evidence of food in stomach onl4th day; all fry feeding on 23rdduy.Rainbow trout20-30047Evidence of food in stomach on2lst day (16 days at 50'F).Channel catfishat swrm- up5 to l0 days after hatching,depending on water temperature.Tiger muskie968Food presented at swim-up; mostof yolk sac absorbed after 8days.Northern pike,walleye,muskellungeat swim-up50-704Food presented at swim-up, up tol2 days post-hatching.'Variousreports include a range of initial feeding times and water temperatures. It isimportant to note that in some instances, evidence of food in the stomach did not occur untilseveral days after swim- up.Table 32 presents feeding frequencies for trout and Pacific salmon fingerlings.Successful feeding of dry feeds to coolwater fishes, such as northern pikeand tiger muskie, requires initial feeding of fry at s-minute intervals, atl0-minute intervals when fry are 2 inches long, and at l5-minute intervalswhen they are 4 inches long, from automatic feeders during the daylighthours.A rule of thumb used by some fish culturists is to feed l%r of the bodyweight per feeding. Therefore, if the fish are being fed at a rate of l0% of