152 FISH HATCHERY MANAGEMENT 



pond. Federal warmwater hatcheries usually stock 40 to 85 adults per acre. 

 This stocking rate is recommended if the fry are to be transferred to a rear- 

 ing pond. If the fry are to be left in the spawning pond, lower stocking 

 rates of 20 to 30 bass per acre are used. 



When ripe fish are stocked into clean ponds containing water approxi- 

 mately 65°F, spawning usually begins within 72 hours, and often within 24 

 hours. Fry will generally hatch within 72-96 hours after spawning, depend- 

 ing on water temperature. They leave the nest after 8 to 10 days and then 

 can be transferred. 



For handling ease and accuracy in estimating numbers stocked, fry 

 should not be handled until they reach 0.6 to 0.8 inch total length. This 

 may be offset by the greater difficulty of collecting entire schools of small 

 bass, because fry may scatter by the time they are 0.8 inch in length. This 

 size is reached in 3 to 4 weeks after spawning during the first half of the 

 spawning period, and in as little as 10 days during the later portion, 

 depending on water temperatures. 



If fry are moved while very small, the water must be clear. Phytoplank- 

 ton, rooted vegetation, filamentous algae, and turbidity can limit visibility 

 and reduce capturing success. Larger fry can be harvested quite readily in 

 spite of these adverse conditions, because they migrate to the edge of the 

 ponds, move parallel to the shoreline near the surface, and can be seined or 

 trapped. 



Smallmouth bass spawning operations are unique in that special equip- 

 ment and techniques often are used for the purpose of collecting fry. The 

 fry do not school well, and scatter in the spawning ponds following swim- 

 up. 



Smallmouth bass spawning ponds may be equipped with gravelled nest- 

 ing sites or elaborate structures containing gravel in a box enclosed by one 

 to three walls for protection of the nesting fish. Each nesting site is marked 

 by a stake that extends out of the water. The sites should be located 20 to 

 25 feet apart in the shallow two- thirds of the pond so males will not fight. 

 The spawning pond can be filled as water temperature rises above 60°F 

 and broodfish are stocked at a rate of 40 to 120 adults per surface acre. 

 Smallmouth bass usually spawn about 10 days to two weeks earlier than 

 largemouth, when water temperature reaches 62 to 63°F. They are more 

 prone to desert their nests during cold weather than largemouth bass. If fry 

 are to be transferred, the spawning pond should not be fertilized, because 

 observation of the nesting sites is necessary. When spawning activity is not- 

 ed, nests must be inspected daily with an underwater viewing glass. This 

 consists of a metal tube 3-4 inches in diameter, fitted with a glass in one 

 end. When eggs are noted on a nest, the stake is tagged or marked in some 

 way to indicate when the fry will hatch. After hatching, a retainer screen is 

 placed around the nest before the fry swim up. They will be confined and 



