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Rearing temperature was used to monitor muscle growth patterns of sea bass Dicentrarchus labrax , L. from hatching to the commercial size (350 g, 30 cm). At this moment, the white muscle cellularity, proximate composition and organoleptic parameters of the fillet were analysed to evaluate the influence of temperature on the structure and quality of the commercial product. One ambient (A/A) and three warm regimes of temperature were compared. In warmed tanks temperature was raised to 19 °C: during the larval period (W/A), only during the cool seasons (winter and early spring) (A/W), or both during the larval period and cool seasons (W/W). High temperature during the larval period was positive for an advanced yield of fingerlings and early juveniles. Winter heating of juveniles also advanced the time to reach 200 g by 25 days. However, independently of the thermal regime all fish attained the commercial size at approximately 600 days. Temperature modulated the rates of hypertrophy and hyperplasia of white muscle fibres throughout the larval, fingerling and juvenile periods, such that at commercial size the number and size distributions of muscle fibres varied depending on the previous thermal story. Thus, the density of muscle fibres (number/mm 2 ) was maximum in tank W/A (212.19 ± 8.77) and minimum in W/W (151.95 ± 8.7) ( p

Sea bass (Dicentrarchus labrax L.) has been widely farmed in the last decade. In order to a better understanding of the final quality of this species, muscle cellularity and quality parameters of the flesh were studied on 14 specimens of wild and 11 farmed Atlantic sea bass, at approximate commercial size (weight 350 g, length 32 cm). White muscle cellularity was evaluated by means of the following parameters: number and diameter of muscle fibres, as well as the muscle fibre size distribution, throughout the total cross-section of the flesh. To ascertain the flesh quality, several physico-chemical parameters (moisture, protein, total fat, fatty acids, hydroxyproline, collagen and pH) were analyzed, and textural mechanical properties (hardness, springiness, chewiness, cohesiveness, gumminess) were determined objectively with a texturometer. Muscle cellularity was different between both groups, such that muscle fibre density was higher for wild specimens (pb0.05). Farmed sea bass showed a higher content of moisture and protein (pb0.01), and a lower flesh pH, and hydroxyproline and collagen contents (pb0.01). Despite of the fact that the total fat did not show significant differences between both populations, saturated and monounsaturated fatty acids were significantly higher in farmed than in wild sea bass, whereas wild fish showed a higher content of polyunsaturated fatty acids (pb0.05). No significant differences were found in the total content of N3 fatty acids between both groups. All textural properties were significantly higher in wild than in farmed fish (pb0.001), all of them show a positive and significant correlation with muscle fibre density, pH, hydroxyproline and collagen contents. Changes in these parameters determined marked differences in the flesh quality of wild and farmed sea bass, whereas no relationship was found between muscle cellularity and nutritional composition of the sea bass. According to our results, genetic factors as well as the influence of extrinsic factors such as feeding regimes and/or exercise may determine significant variations of some structural and flesh quality parameters of the sea bass. D 2005 Elsevier B.V. All rights reserved.

Recently, it has been found that the thermal experience during the earliest phases of development could determine the larval and postlarval growth characteristics of teleosts. In order to investigate the effects of the early temperature regime on the advanced stages of growth of sea bass, Dicentrarchus labrax L., this species was reared during the vitelline phase at two temperatures: natural temperature (i15 jC) and 17.7F0.1 jC, and then larvae transferred to common temperature (natural temperature). Muscle growth was studied by morphometric and histochemical techniques (mATPase and NADH-TR). Body length and body mass were also measured. During the vitelline phase, muscle growth was similar in both experimental groups, but at 25 days, both hypertrophy and hyperplasia of white muscle fibres were greater in the prewarmed group (p

Two genetically different populations of sea bass, Dicentrarchus labrax L., Atlantic (Atl.) and Mediterranean (Med.), were subjected to the following incubation/cultivation temperatures (T): 15 °C/natural, 17 °C/natural, 15/19 °C, 17/19 °C (natural T averaging 15 °C and raising gradually). Muscle cellularity was measured at different larval stages for each T regime. During the vitelline phase, muscle growth was mainly due to muscle fibre hypertrophy. In Med. larvae, higher incubation T (17 °C) increased the area of white and red fibres at hatching, while in Atl. larvae there was no significant T effect at this stage. At mouth opening, the area of white fibres increased at 19 °C in Atl. larvae (P

An early myopathy affecting the myotomes of a stock of sea bass is described. By electron microscopical examination different degrees of muscle lesions were first detected in recently hatched larvae. Muscle fibres underwent a degenerative process, that according to the gravity of the lesions and age of the fish was sequenced in four stages. Necrotic muscle fibres were abundant in the myotomes of post-larvae (more than 60 days). Although this degenerative myopathy is non-specific, the importance lies in its progressive sequence. Vitamin E-selenium deficiency and uncontrolled peroxidation of the lipid content in the feed is thought to be the cause of the problem. The possible implication of the myopathy in the appearance of a high percentage of lordosis in the same stock of sea bass is discussed.