Fish Hatchery Management - fisheries & aquaculture

362 FISH HATCHERY MANAGEMENTCHANNEL CATFISHChannel catfish have been safely transported at loadings presented inTable 41. Experience will dictate whether or not the suggested loadings aresuitable for varying situations. If the trip exceeds 16 hours, it is recommendedthat a complete water change be made during hauling'Catfish also may be transported as sac fry and in the swim-up stage'Most transfers of these stages should be of relatively short duration. Oxygensystems alone are satisfactory when fry are hauled, and have some advantagesover the use of pumps because suction and spraying turbulence iseliminated. If pumps and spray systems are used, the pump should beoperated at a rate low enough to minimize roiling of water in the compartments.Sac fry, 5,000 per 1.5 gallons of water, have been shipped successfullyin l-cubic-foot plastic bags for up to 36 hours. water temPeratureshould be maintained at the same level fry experienced in the hatchery'Although it may be advantageous to gradually cool the water for shippingsome warmwater species, it is not recommended for channel catfish fry.Fingerlings of l-6 inches ship well for 36 hours. As with salmonids, thenumber and weight of fish transported varies in proportionto the size ofthe fish and duration of the shipment.The following guidelines may be of value for hauling channel catfish:(t) Four pounds of l6-inch catfish can be transported per gallon of waterat 65'F.(2) Loading rates can be increased by 250k for each 10'F decrease in watertemperature, and reduced proportionatelyfor an increase in temperature.(g) es flsh length increases, the pounds of fish per gallon of water can beincreased proportionally. For example, a tank holding I pound of 4-inchTABLE 4I. POUNDS OF CATFISH THAT CAN BE TRANSPORTED PER GALLON OF 65'FWATER. (souRcE, MILLARD AND MccRAREN, UNPUBLISHED)NO. OF FISHPER POUNDIRANSIT PERIOD IN HOURSl2l61.02.04.050125250500l,00010,0006.305.905.003.452.952.20t./Jt.250.205.554.804.12.502.201.751.651.000.204.803.452.952.051.801.501.250.700.20