foods we used included 9 commercial foods 

 and 2 gelatin-bound formulations that we 

 prepared. Concurrent studies on food particle 

 size suggest that juvenile shrin-ip prefer large 

 food particles which they can hold and break 

 pieces fronn rather than small particles that 

 can be ingested whole. 



We also directed research toward the prob- 

 lem of bringing penaeid shrimp into spawning 

 condition in the laboratory. Adult shrimp, held 

 in four ponds and several large tanks inside the 

 laboratory, were fed different diets and ob- 

 served for sexual developnaent. Only males 

 in ponds showed apparent signs (externally) of 

 sexual maturation. 



We added several new research facilities 

 and modified others this past year. Twelve 

 concrete tanks, 3 m. long, 1 m. wide, and 1 m. 

 deep (10 ft. by 3 ft. by 3 ft.) were constructed 

 adjacent to our East Lagoon Laboratory. These 

 tanks are connected to the Laboratory's sea- 

 water system and are covered by an open- 

 sided shed roofed with fiberglass. A heat ex- 

 changer was incorporated into the sea-water 

 system at Fort Crockett. A 7,700-liter (2,100- 

 gallon) tank, six 1,850-liter (500-gallon) tanks, 

 and equipment for regulating water tempera- 

 ture in the tanks were installed in the East 

 Lagoon Laboratory. We now have a pellet 

 maker that we can use to make experimental 

 foods in sufficient quantity for large-scale 

 experimentation. We made many modifications 

 to facilitate handling and care of larval shrimp, 

 and installed a light room for the mass culture 

 of algae. In addition, a contract was let to the 

 U.S. Army Corps of Engineers for a design to 

 convert the basement of a demolished building 

 into a recirculating sea-water system. 



Personnel in the Florida Bay Ecology Studies 

 Project prepared nnanuscripts that sum- 

 nnarized the results of past research. Follow- 

 ing the recomn-iendation of the budget review 

 committee, we terminated this project at the 

 end of the year and transferred the personnel 

 to the Bureau's TABL (Tropical Atlantic 

 Biological Laboratory), Miami, Fla. 



Harry L. Cook, Program Leader 

 Larval Culture 



We concentrated during the year on deter- 

 mining the physiological requirements of 

 shrimp larvae and developing a prototype 

 hatchery for the culture of larval shrimp. To 

 supply food for the larval shrimp, we also spent 

 considerable time developing a method to grow 

 mass cultures of algae in artificial media. 



Larval physiology .-- As the result of feeding 

 experiments completed during the year, we 

 concluded that Thalassiosira sp. is the most 

 suitable alga of those tested as food for the 

 larval shrimp. Other algae tested were 

 Skeletonema costatum, Cerataulina sp., Cyclo - 

 tella nana , and Isochrysis galbana . Table 2 



Table 2. --Concentrations of Thalassiosira 

 supporting the best survival of brown 

 shrimp protozoeae, Biological Laboratory, 

 Galveston, Tex. 



■"■ First- stage protozoea. 

 ^ Second- stage protozoea. 

 ^ Third-stage protozoea. 



shows the results of one experiment in which 

 brown shrimp protozoeae were fed 

 Thalassiosira . Further analysis of these data 

 showed that protozoeae 1 survived best when 

 Thalassiosira was supplied at rates of 180,000 

 to 190,000 cells per larva per day; protozoeae 

 II at rates of 240,000 to 290,000 cells; and 

 protozoeae III at 340,000 to 370,000 cells. 

 In another experiment myses of brown shrimp 

 were fed Artemia nauplii and Thalassiosira . 

 Those animals fed a mixture of Artemia and 

 algae grew faster than those fed only Artemia, 

 but survival was similar except whenthenum- 

 bers of Artemia nauplii supplied were too 

 low. 



We performed two experiments to determine 

 the effects of salinity on the growth and survival 

 of larvae of brown shrimp. All larval stages 

 in these experiments were held at salinities of 

 24, 28, 30, and 34 p.p.t. (parts per thousand). 

 EDTA was added to the water in which a 

 portion of the shrimp were held. Survival was 

 best at 28 and 30 p.p.t. Variable survival at 

 34 p.p.t. indicated that the salinity level prob- 

 ably was near the upper limits of tolerance. 

 Larvae survived well at 24 p.p.t. with EDTA, 

 but they suffered complete mortalities when 

 EDTA was absent. EDTA benefited all stages 

 of larvae at all salinities. 



A further test of the effect of EDTA involved 

 the use of a synthetic sea water. Protozoeae III 

 were placed in synthetic sea water (30 p.p.t.) 

 with and without EDTA. Survival was similar 

 in the two groups, but the larvae developed 

 fastest in the water with EDTA. 



Mass culture. -- Work was directed primarily 

 to the development of a prototype shrimp 

 hatchery. We modified equipment, incorporated 



