Fish Hatchery Management - fisheries & aquaculture

t94 FISH HATCHERY MANAGEMDNTillFIGURE 66. Commercially available shipping boxes can be used to transport fisheggs. The boxes should be constructed to keep the eggs moist and cool withoutactually carrying them in water. (l) A wet cloth is placed in the shipping trayand the eggs are carefully poured into the tray. (2) The tray should not be filledto the point where the next succeeding tray will compress the eggs and put pressureon them. The cloth is then carefully folded over the eggs and the next trayput in place. (S) fh" top tray is filled with coarsely crushed ice or ice cubes toprovide cooling during shipping. The melting ice also will provide water to keepthe eggs moist. Ice should never be used directly from the freezer and should beallowed to warm until it starts to melt before it is placed with the (A) Th""ggs.insulated lid is put in place, and the box is sealed and properly labeled forshipping. (FWS photos.)and the fry have fallen through the mesh cloth, the trays are removed withthe dead eggs that remain on them. These units are relatively cheap andeasy to maintain, and egg picking is relatively simple. The disadvantagesare that rearing troughs must be available, there must be some means ofexcluding light from the troughs while the eggs are being incubated, andthere is always a danger of improper water flow through the trays.CLARK-WILLIAMSON TROUGHThe Clark-Williamson trough is a tray-hatching system for incubatinglarge numbers of eggs. The eggs are held on screen trays and are stackedvertically rather than being placed horizontally in the trough. Dam boards