Food and feeding of the brine shrimp Artemia franciscana (Brazilian Macau population) in semi-intensive culture

Campos, Alberto Alves (2000) Food and feeding of the brine shrimp Artemia franciscana (Brazilian Macau population) in semi-intensive culture. Masters thesis, Memorial University of Newfoundland.

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Abstract

The brine shrimp Artemia spp. is a widely used food item in aquaculture. Almost the entire worldwide production of brine shrimp eggs and biomass comes from extensive harvesting of inland saline lakes or coastal solar saltworks. Declining salt prices and growing aquaculture demand has switched the focus to Artemia production in hypersaline environments. NE Brazil has a salt-producing area of 35,000 ha, half of which is abandoned or under strictly artisanal operation. The present research evaluated the effect of supplemental feeding on Artemia franciscana (Brazilian “Macau” population) production and developed semi-intensive culture techniques for this region. -- Preliminary laboratory trials with dried microalgae (Spirulina maxima) were performed to test feeding rations and a feeding table was produced. Low cost feedstuffs available in NE Brazil were evaluated for their digestibility and processing yields, and three brewery by-products were selected (i.e., malt bran, brewer's yeast and spent grains). These were then tested individually and combined in laboratory feeding trials, and their performance was recorded as growth and survival of the Artemia. Malt bran showed significantly better results for both parameters and was selected to be tested in the field. -- Malt bran was efficiently converted into biomass by the Artemia (FCE = 39.16 %) and supplemental feeding was very effective in increasing biomass production. Monthly yields in fertilized control ponds averaged 306.17 kg• ha⁻¹, while feeding ponds produced up to 977.78 kg• ha⁻¹. Increasing feeding levels (rations), although not showing marked differences in size and survival, exhibited gains in individual weight and, consequently, in biomass output. The fatty acid profile of the cultured Artemia was greatly influenced by the diet, while protein content and amino acids did not show significant variations among treatments. -- High salinities were the most efficient predator control method in semi- intensive field systems, and a minimum of 90 ppt was identified as a safe limit to avoid the major predators in the area (i.e., cyclopoid copepods and the fish, Poecilia vivipara). The high mortalities experienced (above 70%) were believed to be related to high temperatures and stocking densities. Measures should be taken to reduce pond water temperature (deeper ponds, shading) and stocking densities below 100 ind• L⁻¹ are recommended.

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