Fish Hatchery Management - fisheries & aquaculture

BROODSTOCK, SPAWNING. AND EGG HANDLING 153FIGURE 46. Spawning and rearing of smallmouth bass in ponds. (l) Male smallmouthbass guarding eggs (a.ro*) on the gravel nest. (Z) Nests are inspecteddaily with an underwater viewing glass, and (3) a retaining screen is placedaround the nest after the eggs hatch. (+) fne fry are transferred to a rearingpond after they swim up. (fWS photos.)can be readily captured for transfer to rearing ponds (Figure 46). A periodof 14 to 2l days normally can be expected between the time eggs are depositedand the time fry rise from the nest. Most fish culturists transfer smallmouthbass fry to rearing ponds, although good results have been obtainedwhen they were reared in the spawning pond.An alternative approach to smallmouth bass spawning involves the use ofportable nests within a pond. These nests are constructed from I x 4-inchlumber, 24 inches square with a window screen bottom. A nest of l-3-inchdiameter rocks, held in a 16 x 16 x 2-inch hardware cloth basket, is placedon the screen frame bottom. Fry are harvested by lowering the pond level,and gently moving the baskets up and down in the water, washing the frythrough the rocks and onto the screen bottomed frame. The fry are thenrinsed into a container for transfer to a rearing pond. This technique also