Table 1. — Continued. 



1971 



Month Day 



Algae 



Hour 



Larval 

 stage 



Larval 

 count 



Residual 



Feed 



Artemiu 



Residual Feed 



April 7 — continued 



April 8 



April 

 April 



April 

 April 



10 



289,000 



No. cells/ml 



187,500 S 



445,000 C 



45.000 S 



507.500 C 



No. cells 

 fed/ml 



300.000 S 

 312.000 S 



231.000 S 



131,000 



No./ml 



3.0 



0.2 

 3.5 



3.4 

 1.4 



3.8 



3.4 



5.2 



18.6 

 K 14.9 



4.0 

 5.0 



5.0 



5.0 



- 8.0 



^20.0 



' N = Nitzschia sp. 



- Frozen Anemia (Anemia did nol hatch). 



airstones along the side and one in the middle of the 

 tank aerated the water. 



The food used initially was the diatom 

 Skc'letonema costaiiim; however, live Nitzschki sp. 

 and Cyclotella nana were also present. Because this 

 e.xperiment was conducted in a greenhouse, the ad- 

 ditional species, which were introduced inadver- 

 tently, grew in the tank. Since C. nana had also been 

 frozen and was present in the tank, it was added to 

 the experiment. Frozen cultures of Nitzschia sp. 

 were not available, so it was decided to only monitor 

 its presence. 



Examination of Table I will reveal that at times the 

 uneaten cells remaining in the tank were at a higher 

 level than that fed. These discrepancies are due to 

 counting error. 



.Aliquot counts of the population on 8 .April 

 showed that 95^r of the larvae had advanced to mysis 

 I stage. Unfortunately, because two successive 

 days — 10 and 1 1 .April — of poor hatches ot'Arteniia 

 occurred, frozen Artemia were used as food. The 

 frozen Artemia sank to the bottom, deteriorated 



rapidly, and caused apparent decline in water qual- 

 ity. Before fresh seawater could be exchanged and 

 before freshly hatched Artemia could be added, a 

 number of the larval shrimp perished. Only 429f of 

 the population survived to the postlarval stage. 



A second rearing experiment was performed in 

 May 1971 using two 1,893-liter (500-gal) fiber glass 

 tanks with conical bottoms. Average length of the 

 shrimp that spawned was 191 mm. and the average 

 number of eggs spawned was 2.^ I. ()()() per shrimp 

 (range 71,000-380,000) with an individual hatching 

 success of about 12.8% (range of 0.5-35.7). The 

 spawn from each shrimp was divided into equal parts 

 and each part v\as poured into one of the rearing 

 tanks. 



Experiment II 



In E.xperiment II. Tank I (Table 2). two species of 

 concentrated frozen algae, Skeletonema costatiim 

 and Tetraselmis sp., were used, the latter being in- 

 troduced during the advanced protozoeal II stage. 



36 



