FISHERY BULLETIN: VOL. 70. NO. 1 



total biomass increase of shrimp fed their best 

 diet for 6 weeks was only approximately 50% 

 higher than initial biomass. Better results (on 

 an individual weight basis) using Penaeus duo- 

 rarum were obtained from animals grown on a 

 sand substrate than those grown in bare tanks. 



The greatest promise for economical shrimp 

 production lies in determining the exact nutri- 

 tional requirements and developing an inexpen- 

 sive artificial diet from feedstuffs for these spe- 

 cies. Current commercial practices in Japan 

 employ chopped clam (predominantly Tapes 

 semidecussata, Reeve) as a diet for rearing 

 shrimp. Despite the high market price for cul- 

 tured shrimp in Japan (the retail price of cul- 

 tured shrimp ranged from $4 to $10 per pound 

 in 1970), shrimp farming there tends to be a 

 marginal enterprise because of the high cost of 

 a clam diet. However, in other parts of the 

 world where shrimp does not command such a 

 luxury price, the use of a high-value product 

 such as clam for shrimp feed is prohibited. 



Pelleted diets (i.e., pellets containing all the 

 chemical ingredients thought to be important 

 to animal growth) have been designed consisting 

 of purified soybean meal, glucose, sucrose, starch, 

 glucosamine, chitin, cellulose, soybean oil, citric 

 acid, succinic acid, amino acid, minerals, vita- 

 mins, and cholesterol (Kanazawa et al., 1970). 

 After growing penaeids on such diets, the ani- 

 mals were in excellent physiological condition, 

 but in the best group, total biomass increase was 

 only 72% of the control group fed chopped clam. 

 Thus, little progress has been made toward estab- 

 lishing nutritional and environmental require- 

 ments that will yield optimum growth (total 

 biomass increase) and survival of penaeid 

 shrimp. 



In the present study, an attempt was made to 

 develop a suitable experimental culture system 

 which could serve as a model for future nutri- 

 tional and environmental studies. Several en- 

 vironmental factors were examined, and, as a 

 result, environmental conditions were created 

 which would allow acceptable growth and sur- 

 vival. Having first established suitable culture 

 conditions, several diets were evaluated in pre- 

 liminary studies of the nutritional requirements 

 of shrimp. 



MATERIALS AND METHODS 



Both environmental and nutritional studies 

 were conducted in round fiber glass culture tanks 

 measuring approximately 1 m deep by 1 m in 

 diameter and equipped with a venturi type cen- 

 ter drain which maintained a water depth of 

 0.75 m. Three replicates were maintained for 

 all treatments. 



Water (ranging in salinity from 26.8 to 

 29.3^r) from the Skidaway River was filtered 

 through an oyster shell and sand filter to re- 

 move major food particles. Filtered water was 

 heated to 30° C in a stainless steel heat exchang- 

 er and jetted into each tank at a rate of 1.9 

 liters/min through flow-control nozzles which 

 were aimed so that the agitation of the water 

 column in each tank was minimal. Temper- 

 ature ranged from 25° to 28°C in each tank 

 throughout the experimental period. 



White shrimp (P. setiferus) obtained from the 

 Savannah, Ga., river and tributary systems were 

 used in all environmental experiments, and 

 brown shrimp (P. aztecus) obtained from the 

 Tampa Bay, Fla., area were used in the nutri- 

 tional studies. Shrimp weighing 4 db 0.8 g 

 (mean and standard deviation based on 480 

 weighed shrimp) were selected from the above 

 stock and used in all environmental studies (10 

 animals per tank) and fed pelleted diets (Table 

 1, Diet 1) at a rate of 5% of their biomass daily, 

 on a dry weight basis. Shrimp were weighed 

 each week and the percent increase or loss re- 

 corded on a wet weight basis. 



SUBSTRATE STUDY 



Sand-shell substrates suitable for burrowing, 

 subdivisions of tank bottoms, and bare fiber glass 

 tank bottoms were provided for replicate groups 

 of shrimp, and relative survival rates among the 

 treatment groups were compared over a 5-week 

 period. Sand-shell substrates were placed di- 

 rectly onto the tank bottom in one group, and in 

 another group, the same substrate was placed on 

 a perforated platform 10 cm above the tank bot- 

 tom, allowing a flow of water through the drain 

 below the sand surface. Such an arrangement 

 was designed to test the eflfect of decreasing the 



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