Culture of Juvenile and Adult Shrimp 



At the beginning of the fiscal year, we were 

 testing four methods of growing shrimp in our 

 ponds. In each of four 0.02-hectare (l/20-acre) 

 ponds, immature brown shrimp had been 

 stocked at a density of one shrimp per 

 0.2 m.^(2 ft. 2) of bottom surface. This year 

 we stocked juvenile rather than postlarval 

 shrimp so that we could concentrate our efforts 

 on determining how to offset the slow growth 

 (past studies) experienced when shrimp in 

 ponds became 76 to 100 mm. (about 3-4 

 inches) long. Table 3 summarizes the treat- 

 ment and results in each pond. 



Feeding rates throughout the 1 14- day study 

 were based on initial stocking density, but it 

 was apparent at harvest that we had supplied 

 too much food. Loss of nutrients from the 

 excess food apparently supported dense growth 

 of algae in both ponds. Temperatures reached 

 34° C. (93° F.), and pH values rose above 9 

 several times in the study. To prevent oxygen 

 levels from dropping below 2 ml. per liter, 

 we aerated each pond with a low-pressure, 

 high- volume air punnp. This technique did 

 maintain oxygen levels above 2 ml. per liter 

 in pond 2, but the shrimp suffered extensive 

 mortality due to some other factor or combina- 

 tion of factors. 



At the time of harvest, we recovered 14 

 white shrimp with the brown shrimp from pond 



4. Although they were the same size as the 

 brown shrimp when stocked, their average size 

 at harvest was 23 per pound as compared to 55 

 per pound for brown shrimp. 



Shrimp retained from the feeding studies 

 were restocked in our ponds and examined 

 periodically in the fall and winter for signs 

 of sexual development. Males in two ponds had 

 signs of advanced maturation. Spermatophores 

 were visible as whitish bodies beneath the 

 lower posterior edge of the carapace (fig. 4). 

 Several females had mated, but only a few had 

 developing ovaries. Sexual development was 

 arrested by the approach of winter and the 

 accompanying low water temperatures. At that 

 time we removed a number of the largest 

 shrimp from the ponds and placed them indoor s 

 in a 9,000-liter (2,400-gallon) tank in which the 

 temperature was maintained at 27° C. (81° F.) 

 and salinity at 33 p.p.t. These shrimp failed to 

 show any signs of maturity over a 4-month 

 period. 



This spring we continued to try to bring 

 shrimp into spawning condition in a controlled 

 environment. Adult shrimp, placed in each of 

 four ponds and in seven large fiberglass tanks 

 in the laboratory, are fed different diets and 

 observed closely for sexual development. To 

 date, only pond-reared nnales show signs of 

 becoming mature. 



Since the construction of our first ponds, one 

 of our major problems has been to stabilize 



Table 3. — Summary of results obtained from experimental rearing of shrimp in four brackish- water 



ponds at Galveston, Tex. , 1968 



Pond 

 number 



Treatment 



Size at 

 stocking 



Size at 

 harvest 



Average 



individual 



gain 



Survival 



Total food 

 added 



Total weight 

 gained or lost 



No food or 

 fertilizer. 



Kilo- 



Kilo- 



Number per pound Grams Ounces Percent grams Pounds grams Pounds 

 59 52 1.0 0.03 82 -0.6 -1.3 



Fed 5 percent 

 of body weight 

 daily. Trout 

 food 50 per- 

 cent; rabbit 

 food 50 percent. 



33 



21 



8.0 



.28 



22 



58.7 129.5 



-6.7 -1A.8 



Fed 5 percent 

 of body weight 

 daily. Trout 

 food IDO per- 

 cent; fertil- 

 ized once-'-. 



62 



3A- 



6.1 



.22 



68 



31.1 68.6 



3.5 



7.8 



Fertilized-"- 

 once. 



70 



55 



1.8 



,06 



60 



-.6 



-l.A- 



^ N:P:K = 1D:<40:K) 



