Combined effects of rearing density and tank colour on the growth and welfare of juvenile white sea bream Diplodus sargus L. in a recirculating water system

Abstract

Appropriate rearing conditions for successful farming of white sea bream Diplodus sargus L. have not yet been studied in depth, while one of the major problems is the species increased aggressiveness. Given the known e¡ect of density and background colour on ¢sh growth, welfare and social behaviour, the present study aimed to investigate whether the two factors combined could favour D. sargus performance. Juveniles (17.37 AE 0.06 g) were reared in white, light blue and black tanks under low (7 ¢shtank À1 or 1.96 kg m À 3 ) and high (28 ¢sh tank À1 or 7.79 kg m À 3 ) density for 87 days. Water quality was not a¡ected by experimental treatments. The best overall performance (growth, food utilization, body protein content, liver fatty acids) was achieved under low density and white or light blue tanks. Increased incidence of social interactions was indicated in ¢sh under high density or when reared in light blue and black tanks. The present results clearly suggested that the use of black tanks should be avoided. On the other hand, stocking D. sargus at a density of up to 7.79 kg m À 3 may be feasible because productivity was greater even if growth was slower. In this case, however, the use of white tanks is highly recommended.

Larvicultura de matrinxã em tanques de diferentes cores

“…Semelhantemente ao presente trabalho, o uso de tanques de cores claras favoreceu a criação de larvas de P. fl uviatilis (Tamazouzt et al, 2000), Colossoma macropomum (Pedreira & Sipaúba-Tavares, 2001) e juvenis de C. carpio (Papoutsoglou et al, 2000), Oncorhynchus mykiss (Papoutsoglou et al, 2005), Verasper moseri (Yamanome et al, 2005), P. fl uviatilis (Strand et al, 2007) e Diplodus sargus (Karakatsouli et al, 2007).…”

“…Para outras espécies, a cor do tanque também afeta a sobrevivência (Tamazouzt et al, 2000), o crescimento (Jentoft et al, 2006;Strand et al, 2007), parâmetros bioquímicos (Karakatsouli et al, 2007), pigmentação da pele (Amiya et al, 2005;Doolan et al, 2007), comportamento agonístico e atividade motora (Merighe et al, 2004). Além disso, a coloração do tanque pode levar a um maior contraste do alimento, o que facilita sua captura com conseqüente melhora na produtividade (Pedreira & Sipaúba-Tavares, 2001).…”

Larviculture of two neotropical species with different distributions in the water column in light- and dark-colored tanks

“…On the other hand, pelagic species have eyes placed laterally (Kirchheim & Goulart, 2010). The contrast between the color of the food organism and the wall of the tank is important for the visual perception of the prey by the larvae (Krise & Meade, 1986;Ostrowsky, 1989), providing higher or lower visibility and consumption of prey (Pedreira & Sipaúba-Tavares, 2001;Strand et al, 2007), and also affecting survival (Tamazouzt et al, 2000;Pedreira et al, 2008b), growth (Jentoft et al, 2006;Strand et al, 2007;Monk et al, 2008), biochemical parameters (Karakatsouli et al, 2007), skin pigmentation (Amiya et al, 2005;Doolan et al, 2007), agonistic behavior and motor activity (Merighe et al, 2004), and finally productivity (Pedreira & Sipaúba-Tavares, 2001). …”

Behavioural indicators of welfare in farmed fish

“…Galhardo et al (2008) showed that the use of tank substrate affects the reproductive behaviour and physiology, including behavioural needs (see below), in Mozambique tilapia males. Höglund et al (2005) showed that providing hiding materials affects the fear response to alarm cues from conspecifics in crucian carp, while tank design and colour have also been shown to improve farmed fish welfare (Ross et al 1995;Karakatsouli et al 2007). The use of feeding systems or regimes that deliver a responsive ration in relation to appetite levels can also improve welfare by reducing the chances that fish are underfed (Suzuki et al 2008), by reducing competition (Andrew et al 2002;Noble et al 2007b) and by reducing the frequency of injury and damage Suzuki et al 2008).…”