new procedures, and developed new techniques. 

 We modified the larval rearing tanks by adding 

 bulkhead fittings and valves to the bottom of 

 each tank. This arrangement and the addition 

 of a filter screen, which threads into the bulk- 

 head fitting, nnake it possible to filter, drain, 

 or recirculate the water by opening or closing 

 two valves (fig. 2). A high-pressure power 

 washer (500 pounds per square inch) now used 

 for cleaning equipment in the hatchery enables 

 us to wash and rinse a tank in minutes. 



Procedures were developed for estin-iating 

 nunnbers of food organisms and larval shrimp. 

 We use a hemocytometer to count diatoms and 

 an electronic counter for first- and second- 

 stage nauplii of the larval shrimp as well as 

 Artemia nauplii. To estimate numbers of more 

 advanced shrimp larvae and postlarvae, we 

 photograph aliquot samples that we place in a 

 petri dish. These pictures are then placed 

 under a dissecting scope and the shrimp 

 counted. We calculate the mean, standard de- 

 viation, mortality rate, and confidence limits 

 of the population from these counts. 



Gravid white and pink shrimp that we cap- 

 tured offshore spawned successfully in the 

 laboratory. Spawning occurred in the 950-liter 

 (250-gallon) rearing tanks and several 19-liter 

 (5-gallon) carboys. After a female spawned in 

 a carboy, we removed her and put the eggs in 

 the large rearing tanks. We fed the diatom 

 Cyclotella nana to the protozoeal stages and 

 Artemia to the mysis stages. Survival from 

 protozoea to mysis was poor for both species. 

 Although we increased the amount of diatoms 

 fed to the shrimp from 30,000 cells per 

 milliliter to 750,000 cells per milliliter, 

 shrimp larvae continued to die. Only 1 1 per- 

 cent of the pink shrimp and 18 percent of the 

 white shrinnp survived. We attributed this poor 

 success directly to the diatom Cyclo - 

 tella , which is an unsuitable food when used 

 alone. 



The successful hatching of white shrimp was 

 no doubt due to the fact that their ovaries were 

 fully ripe. Their eggs were a dark olive green. 

 We exannined each female and found no attached 

 spermatophore. Water temperature in the 

 spawning tanks were 26.9° to 28.2° C. (80.4°- 

 82.8° F.), and the salinity 29.1 to 31.2 p.p.t. 

 EDTA at a level of 0.1 g. per liter (0.01 ounce 

 per gallon) was placed in each tank and carboy 

 before the shrinnp spawned. 



Diatoms are now cultured in artificial sea 

 water in 300-liter (79-gallon) tanks in a tem- 

 perature-controlled light room. Banks of fluo- 

 rescent lamps that can be raised or lowered 

 were constructed to provide the required in- 

 tensity of light. At present, electric pumps 

 transfer the diatoms to the harvesting tanks; 

 however, construction is underway to provide 

 space in the attic where the algae culture room 

 can be transferred. From the attic the algae 

 will be able to flow by gravity to the rearing 

 tanks. 



Algal culture .-- The diatom, Cyclotella nana , 

 was grown for shrimp food in carboy cultures 

 and in mass cultures with Instant Ocean-"- arti- 

 ficial sea salt (mixed in tap water and prepared 

 without heat) as the basic culture media. To 

 this salt water we added Tris buffer, EDTA, 

 KNO3 , Na2Si03, vitamins B-12 and thiamin, 

 and iron, either as FeClj or FeNH^(SO^)2. 

 We counted 3 to 6 million diatom cells per 

 nnilliliter. After the number of diatoms reached 

 a peak (usually 2 days), we harvested about 

 two-thirds of the volume daily and replaced it 

 with new medium to maintain the quality of the 

 culture. We nnaintained cultures for as long as 

 1 4 days. 



We studied how artificial sea- salt media 

 would be affected by adding three sources of 

 iron--ferric sequestrine, ferric annmoniunn 

 sulfate, and ferric chloride. Ferric sequestrine 

 and ferric ammonium sulfate supported good 

 growth of Skeletonema sp. in test-tube cul- 

 tures, whereas ferric ammonium sulfate sup- 

 ported the best growth of Thalassiosira sp. in 

 tube and carboy cultures. 



General suitability of the Instant Ocean-tap 

 water medium for certain flagellates, dino- 

 flagellates, and diatoms in tube cultures was 

 indicated by good growth of 19 to 22 organisms 

 tested. 



Harry L. Cook, Project Leader 

 Ausbon Brown 

 Cornelius R. Mock 

 M. Alice Murphy 



Food and Experimental Environments 



The purpose of our research has been to 

 find a suitable food for raising shrinnp. Once 

 we have accomplished this, we can turn our 

 energies to selective breeding. We studied the 

 growth of shrimp fed various foods prepared 

 in our laboratory and fed connmercially avail- 

 able foods. We have also completed studies to 

 determine if shrinnp prefer certain sizes of 

 food particles. 



We continued to use the fish protein concen- 

 trate pellet developed last year and modified 

 it to test additional proteins. Pellets were 

 made with fish protein concentrate, cottonseed 

 meal, and soybean meal as the source of pro- 

 tein, either singly or in combination. Test 

 shrinnp ate pellets made with fish protein con- 

 centrate but not pellets made only with cotton- 

 seed nneal or soybean meal. The aninnals tore 

 apart the pellets containing fish and vegetable 

 meals and appeared to extract as much of the 

 fish protein concentrate as possible. A great 

 portion of the vegetable nnaterial was left on 

 the bottonn of the tank. All experiments had 

 negligible growth and poor survival, apparently 

 from a heavy growth of micro-organisms, 

 fouling of the water, or a connbination of these 

 factors. 



Trade names referred to In this publication do not 

 imply endorsement of commercial products. 



