determined gravimetrically. The lipid material was saponified with 10 ml 0.5 N 

 potassium hydroxide-methanol. 



Fatty acids were methylated with 14 percent boron trifluoride-methanol 

 (28). Fatty acid methyl esters (FAME) were injected into a single column 

 Varian Aerograph 1200 gas-liquid chromatography unit operated isothermally 

 at 180°C and equipped with a flame ionization detector. FAME were separated 

 on a 15 percent diethylene glycol succinate (DEGS) column, on 100-120 mesh 

 Chromosorb W-HP, 2.1 m long x 3.2 mm O.D., supplied with 75 ml/min flow 

 of nitrogen as the carrier gas and a three percent ethylene glycol succinate 

 polyester-Z (EGSP-Z) column (same dimensions as DEGS) on 100-120 mesh 

 Gas Chromosorb Q support with 40 ml/min nitrogen. Identification and 

 quantification of the FAME were made with an electronic integrator (Hewlett 

 Packard 3380A) supplied with the relative retention times of authentic 

 standards and literature values for published oils (2). Cod liver oil was used as a 

 secondary standard (3) and heptadecanoic acid (17:0) was used as an internal 

 standard (16). Unresolved chromatogram peaks were detected by comparing 

 the profiles of the two individual column separations. 



RESULTS AND DISCUSSION 



Artemia Diet— Batch Culture 



The total protein levels and amino acid profiles are given in Table 1 5-4 for 

 the wild silversides, their eggs, and laboratory cultured fish of various ages. The 

 cultured fish had been fed the live 3-day-old brine shrimp diet. The amino acid 

 spectrum of the silversides was very similar to the spectrum of migrating 

 Atlantic salmon (15). 



The brine shrimp analysis was similar to the results of Gallagher and Brown 

 (18) who also analyzed San Francisco Bay brine shrimp. These authors stated 

 that methionine in the brine shrimp may be limiting compared to standard egg 

 albumin levels. However, our results showed that the methionine levels in brine 

 shrimp were very similar to tlie level found in the silverside eggs. The major 

 differences between the 3-day-old brine shrimp and the silverside eggs were the 

 lower levels of threonine, serine, proline, valine, and leucine, and the higher 

 levels of arginine in the brine shrimp. 



The silverside eggs contained higher levels of threonine, serine, proline, 

 alanine, leucine, and tyrosine, and lower levels of glycine and methionine than 

 were found in the wild fish. The amino acid profile of the 5-day-old silversides 

 changed substantially from the profile of the eggs. Most of the changes resulted 

 in a general decrease in amino acids from the egg to the larval stage. 



220 



