Fish Hatchery Management - fisheries & aquaculture

BROODSTOCK, SPAWNING, AND EGG HANDLINCI35VARIOUS SPECIES OF FISH AS REPOR'IED IN THE LIl'ERATURE. TEMPERATIjREREMAR KSUpstrcam miqration and maturation, 15 ()0', eggs that had developed to thc l2U ccll stagc in.12.5' uater cgrrlcl toleratc water .tt li5'' for the rernaincler ol' the incubirtion periocl. lhe l2llcellstagc was attained in I l1 hours ol incubation.Eggs reached the 128-cell stage in 72 hours at 4',2.5' but required an additional 24 hours ofdevelopment at that temperature before they could withstand l]5'water'Temperatures in excess of 54' affect maturation of eggs and sperm in adults; normal growthand development of eggs does not proceed at temPelatures above'1!)'; at least 50" mortalityat 54" can be expected.Broodfish should not be held in water temperatures exceeding 56", and preferabh not above54. for at least six months before spawning. Rainbow trout eggs will not develop normally inthe broodfish if constant watel temPeratures above 56" are encountered prior to spawning'fhe eggs cannot be incubated in water below'12'withorrt excessive lossBroodfish can tolerate temperatures greater than 66" but the average water temperature shouldbe .tU .50" for optimal spawning activity and embryo survival. Eggs will develop normally atthe lower temperatures, but mortalities are likely to be high.Eggs do exceptionally well in hard water at 50"Water temperatures should not drop during the spauning season. Temperatules neal anoptimum of 5,tr'are recommended in northern pikc management'The optimum temperature ranges for fertilization, incubation, and fry survival are 4ll 5'l',4U-59",59 70", respectively. If unusually cold weather occurs after the fry hatch, Iry survivalmay be affected. Feeding of fry may also be reduced when temperatures are lou'.Temperature shock between tj5" and higher temperatures may have a more deleterious aflecton freshly fertilized eggs than if the eggs are incubated for l(i to.1,l-hours at 65'beforetransfer to the higher water temperatures