BROODSTOCK, SPAWNING, AND EGG HANDLING 151 



middle and 1 foot or less around the perimeter. In the case of bass and 

 sunfish, the males either prepare nesting sites at random in the pond or use 

 gravel nests or beds provided by the fish culturist. Following spawning, the 

 males guard the nests until the eggs hatch and the fry swim up. Fry are left 

 in the pond and reared in the presence of the adults. Less labor is involved 

 in this method but its use usually is restricted to nonpredatory species such 

 as bluegills, because predation by adult fish can be extensive. Other disad- 

 vantages include the possible transfer of disease organisms from broodfish 

 to fry and lack of control over rearing densities. 



A more popular method involves the transfer of eggs or fry to prepared 

 rearing ponds. This method commonly is used in the culture of bait, 

 forage, tropical, and ornamental fishes, as well as with several predatory 

 species. 



The production of largemouth bass fry for transfer to rearing ponds 

 should begin with the selection of ponds. A desirable pond is of moderate 

 depth, protected from wind action, and 0.75 to 1.5 acres in size, and does 

 not ordinarily develop weeds or dense phytoplankton blooms. If possible, 

 the pond should be thoroughly dried before it is flooded and stocked. 

 Growth of terrestrial vegetation or a green manure crop will provide food 

 for the fry and inhibit undesirable aquatic plants. Careful attention must 

 be given to oxygen levels if such crops are used, however. It is desirable to 

 flood the pond about 2 weeks before bass fry are expected to begin feeding 

 unless a residual supply of food from a previous cycle is present, as it 

 would be if the pond had been drained and immediately refilled. The 2 

 weeks provide enough time for natural food organisms to develop for the 

 small bass. Preparation of ponds for production of food organisms is dis- 

 cussed in Chapter 2. 



Most bass culturists prefer to leave the spawning pond unfertilized to 

 avoid a phytoplankton bloom that will hinder observation of the fish. If 

 there is not ample residual fertility to allow a natural food chain to 

 develop, the pond may be fertilized lightly to produce a zooplankton 

 bloom. 



The spawning pond can be stocked any time after the last killing frost, 

 and preferably near the average date of spawning activity in previous years. 

 At this time, the broodfish should be examined and the ripe fish stocked in 

 the pond. Ripe females have an obviously distended, soft, pendulous ab- 

 dominal region and a swollen, red, protruding vent. Unripe fish can be re- 

 turned to the holding pond for one to two weeks before being examined 

 and stocked. 



It is preferable to keep various age groups separate when spawning 

 ponds are stocked, although this often cannot be done at small hatcheries. 

 Generally the older, larger fish ripen and spawn first. 



The number of bass broodfish to stock depends upon the number of fry 

 desired, the size and condition of the spawners, and the productivity of the 



