BLACK BASS CULTURE 201 



bers of brood fish than we have yet tried in our experiments. Cog- 

 geshall (1923) estimates that a single female may lay from 10,000 

 to 20,000 eggs. If this is true, only a few fish are required to pro- 

 duce as many fry as can be supported by a 1-acre pond. On the other 

 hand the fry appear to suffer a heavy mortality soon after hatching 

 and there is usually considerable loss among the adults early in the 

 season. For these reasons considerably larger numbers of brood 

 fish should be used than is indicated by their egg-laying capacity. 



SUMMARY 



1. In the spring of 1926 a comprehensive series of investigations 

 in pond culture was inaugurated by the Bureau of Fisheries at its 

 biological station at Fairport, Iowa. The experimental work has 

 been largely concerned with the largemouth black bass but some 

 attention has also been paid to the smallmouth bass, black and white 

 crappie, and bluegill sunfish. 



2. The experiments described in this paper were conducted in dirt 

 ponds supplied with water from the Mississippi River. Many of 

 the ponds are quite small and only seven are over one-half acre in 

 area. 



3. Several fertilizers have been tried in the ponds with success, 

 the yield of fish in the fertilized ponds having been much greater 

 than that in the unfertilized ponds. The best results have been ob- 

 tained with mixtures of superphosphate and dry sheep manure and 

 with soybean meal. 



4. Forage fish appear to afford the most practicable method of 

 increasing the natural food supply of bass fingerlings in ponds. In 

 practice, the nursery ponds are stocked with brood minnows in the 

 spring. These fish spawn and thus provide a supply of small min- 

 nows for the bass fingerlings throughout the season. 



5. Everything considered, the golden shiner appears to be the 

 best forage fish for use in bass ponds. The blackhead minnow and 

 goldfish are valuable where minnows are to be raised in separate 

 ponds for feeding to brood stock. 



6. For the propagation of largemouth black bass a combination 

 of spawning and nursery ponds has been found to give the best 

 results. The spawning ponds are heavily stocked with brood fish, 

 using about one male to two females. The fry are trapped when 

 they rise from the nests and placed in nursery ponds which have been 

 previously stocked with brood minnows. These ponds are fertilized 

 at frequent intervals throughout the spring and early summer. 



7. The highest production of bass so far obtained was at the rate 

 of 11,550 three-inch fingerlings per acre. In several instances yields 

 of 8,000 to 10,000 fingerlings per acre have been obtained. 



8. Although conditions in the ponds at Fairport are quite different 

 from those usually thought to be necessary for the propagation of 

 smallmouth bass, very good results have been obtained with this 

 species during the past two years. 



9. Both black and white crappie have been propagated success- 

 fully, the highest production obtained being at the rate of about 

 13,000 fingerlings per acre. 



