GROWTH PERFORMANCE OF Litopenaeus vannamei IN …

1 GROWTH PERFORM ANCE OF Litopenaeus vannamei IN super INTENSI VE M IXOTROPHIC raceway culture with ZERO DISCHARGE USING TAERATION TECHNOLOGY FOR aeration AND extended CO2 DEGASSING Tzachi M . Samocha*, Bob Advent, Eudes S. Correia, Timothy C. M orris, and Joshua S. Wilk enfeld Texas Agr iLif e Resear ch M ariculture Laboratory , Corp us Christi, TX 78418 Losses to viral disease outbreaks and the p otential negative imp act from nutrient-rich water on receiv in g st reams ar e t wo major cha llen ges for t he dev elop ment of sust ainable, b iosecure, and cost-effective shrimp farmin g p ractices. Use of greenhouse- enclosed mixotrop hic sup er- intensive , biofloc domin ated, zero exchan ge sy stems can alleviate these p roblems. A 108 d sup er- intensive grow-out study was conducted in four 40 m3 raceway s wit h wat er p reviously used in a 62 d nursery t rial.

2 Preliminary result s showed t hat high shrimp y ields ( kg/m3), high survival ( ), lar ge size ( g), good GROWTH ( g/wk), and low FCR ( ), are feasible. Addition of freshwater was minimal ( culture volume/d), servin g most ly t o offset evap orat ive losses. T ot al wat er use varied bet ween 99 and 126 L/k g shrimp p roduced. Op erating biofloc sy stems at these p roduction levels requires excessive en er gy to satisfy the high oxy gen d emand of the shrimp and the microb ial commun ities. Up on successful comp letion of the above mentioned study , shrimp and water from one raceway were t ransferred int o an e mp ty raceway at a density of 393/m3 (av. wt. g) with biomass load of kg/m3, to evaluate the p otential use of a new aeration d evice (Taeration , Advan ced Industrial aeration , Tamp a, FL. USA) to purge CO2, p rovide adequate mixin g of the biofloc, and maintain op timal dissolved oxy gen lev els in the culture medium without using p ure o xy gen while redu cin g ener gy consump tion.

3 Prior t o imp lement ing t he T aerat ion devic e, t he DO level in t he ra ceway had been ma int ained using a p ump driven Vent uri in ject or sy st em t o enrich t he wat er wit h a ir and sup p lement al oxy gen. Preli minary result s showed t hat t he T aerat ion system using 3:1 air/water r atio and without oxy gen supp lementation maintained higher DO levels in the culture medium with good mi xin g whi le el imin at ing t he need for t he Vent uri and a ll air-dr iven d evic es (e. g., air blower, air diffusers, airlift p ump s) necessary for mixin g and circu lation. These results suggest that a total of 13 hp (four 2 hp p ump s p lus one 5 hp air blower) p reviously needed t o op erat e t he four raceway s could be redu ced t o 8 HP, while also el imin at ing t he cost for supp lement al p ure oxy gen. T his p resent at ion will summariz e t he result s obt ained in t his st udy and t he effect on select ed water quality indicators and shrimp p erformance.

4 Key words: Litopenaeus vannamei , high-d ensit y , z ero exch an ge, T aerat ion technolo gy