136 



FISH HATCHERY MANAGEMENT 



Table 17. continued. 



SPECIES 



Largemouth bass Annual 



33-95° 



55-80° 



60-65° 



13,000 



broodfish of this species relatively simple. Eggs can be obtained from one- 

 year-old fish that have reached a size of 0.7-1.0 pounds. Brood bass can be 

 expected to spawn satisfactorily for three to four seasons and should be 

 between 3 and 4 pounds at the end of this time. It is suggested that one- 

 third of the broodstock be replaced each year. The food organism can be 

 reared on the station or purchased from outside sources. As a minimum 

 standard, enough food should be provided to produce a weight gain in the 

 broodstock of 50'^ per year. For largemouth bass, as an example, 5 pounds 

 of forage food produce about 1 pound of fish gain, in addition to the 3 

 pounds of forage per pound of bass required for body maintenance. Thus, a 

 1-pound bass being held for spawning should be provided a minimum of 

 5.5 pounds of forage fish. 



Fish typically lose 10-20% of their body weight during the spawning 

 season. Much of this is due to the release of eggs and sperm, and is most 

 pronounced in females. Feeding may be interrupted during courtship or 

 during periods when the nest and fry are protected against predators. Not 

 all species protect their young, but male largemouth bass, bluegill, and oth- 

 er sunfishes do. This weight loss must be regained before subsequent eggs 

 and sperm are developed. Feeding schedules should reflect the nutritional 

 status of the fish and be tailored to their respective life histories. 



Close attention should be given to the quality and availability of the 

 forage fish provided. The forage should be acceptable to the cultured fish 



