A MODEL FOR GROWTH OF ARTEMIA-FRANCISCANA CULTURES BASED ON FOOD RATION-DEPENDENT GROSS GROWTH EFFICIENCIES

Laboratory cultures of Artemia franciscana grown under batch regimes at constant temperatures (28-degrees-C) and salinity (35 g l-1), three initial food concentrations (0.1, 0.4 and 1 M cells ml-1), various daily food rations (0.l-9 M Dunaliella tertiolecta cells Artemia-1), and different population densities (1-16 ind ml-1) were used to develop a model of population growth. Growth rates and gross growth efficiencies (K1) were largely independent of population densities and initial food concentrations but determined by age and daily amount of food ingested. While maximum growth rates were found with the highest rations, K1 max peaked at rations of 0.5 million cells d-1 and decreased at feeding levels above this. A contour plot showing the trend relating K1 to Artemia size and ingestion rate in combination and was used to model growth in analogous controlled feeding conditions. Computer simulations using this model paralleled published results of final 15-day average individual sizes of Artemia. Optimal results for near constant food utilization are predicted for high initial population densities (100 Artemia nauplii ml-1) and daily culls of enough animals to equilibrate food demand with food availability. This strategy could permit a range of Artemia sizes harvested, maximize final individual sizes and retain high total yields (> 1.2 kg dry wt l-1). Effects of different culture strategies are discussed.