The effect of density on sea bass (Dicentrarchus labrax) performance in a tank-based recirculating system

Abstract

Sea bass (Dicentrarchus labrax) (135 ± 4 g) were reared under tank-based recirculating aquaculture system for a 63-day period at four densities: 10, 40, 70, 100 kg m −3. Fish performance, stress indicators (plasma cortisol, proteonemia plus other blood parameters-Na + , K + , glucose, pH, total CO 2 −) and water quality were monitored. At the end of the 63-day period, resistance to infection was also studied by a nodavirus challenge. A 25-day test was performed on fish from two extreme densities (10 and 100 kg m 3) and one intermediate density (40 kg m 3). With regards to the different density treatments, there was no significant difference between the daily feed intake (DFI) and the specific growth rate (SGR) up to a density of 70 kg m −3. No significant difference was found between treatments concerning the feed conversion ratio (FCR) and the mortality rate. No density effect was observed on the fish stress level (plasma cortisol) or on sensitivity to the nodavirus challenge. Under these experimental rearing conditions, the density above 70 kg m −3 has an impact on growth performance (DFI and SGR) indicators and also some blood parameters (CO 2) at the highest density tested (100 kg m −3). This study suggests that a density up to 70 kg m −3 has no influence on sea bass performance and welfare. At 100 kg m −3 , average specific growth rate was decreased by 14% without welfare deterioration according to the welfare indicators monitored.

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“…However, no mortality was observed in any of the selected stocking densities in our current study. Similar results have been reported for farmed fish cultured with good water quality, e.g., rainbow trout, sea bass, red porgy (Pagrus pagrus), African catfish (Clarias gariepinus), and Nile tilapia (Oreochromis niloticus) (Hengsawat et al, 1997;North et al, 2006;Sophie et al 2009;Laizcarrión et al 2012).…”

Performance of Three Different Biofilter Media in Laboratory-Scale Recirculating Systems for Red Seabream Pagrus major Culture

“…The pH was maintained between 7.2 and 7.6. This was slightly lower than normal seawater but is common in recirculating systems and is not a problem for fish growth (Fivelstad et al, 1995(Fivelstad et al, , 1998Sammouth et al, 2009). Salinity remained between 32 and 34 psu in all systems.…”

“…Negative effects of higher density on fish growth performance are generally associated with water quality deterioration and increased aggressive behavior (Ellis et al, 2002). The TAN concentrations of sea bass (Dicentrarchus labrax) at densities of 10 kg/m 3 and 40 kg/m 3 were 1.03 and 1.44 mg/L, respectively, and these were significantly different (Sammouth et al, 2009). Therefore, high stocking densities need high water exchange rates or higher water loading rates to reduce the nitrogen content of the water (Lawson, 1995;Björnsson and Ólafsdóttir, 2006;Foss et al, 2006).…”

“…Each system was stocked with 25 fish. The pH was controlled using soda addition to keep values above 7.1 (Fivelstad et al, 1995(Fivelstad et al, , 1998Sammouth et al, 2009). …”

Densidade de estocagem no crescimento, composição e perfil lipídico corporal do jundiá

“…Apesar do elevado gasto inicial para a implantação de um sistema de recirculação e dos custos fixos com energia elétrica, este sistema requer reduzido espaço, além de permitir o reuso da água, pouca renovação, assim como maior controle dos parâmetros físicos e químicos desta água (SAMMOUTH et al, 2009).…”