Influence of trophic sequence in larval rearing of Sparus aurata (Abstract)
Mazzola, A.; Arculeo, M. (1989). Influence of trophic sequence in larval rearing of Sparus aurata (Abstract), in: De Pauw, N. et al. (Ed.) Aquaculture: a biotechnology in progress: volume 1. pp. 675 In: De Pauw, N. et al. (1989). Aquaculture: a biotechnology in progress: volume 1. European Aquaculture Society: Bredene. ISBN 90-71625-03-6. 1-592 pp., more |
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| Abstract | Sparus aurata is a highly valued seafish in every Mediterranean area with a high commercial value. In some Italian regions it exceeds the standard prices of the best Sparidae species such as sea bass and sargo. In the first 3 months of life, gilthead bream is very vulnerable and sensitive to breeding conditions. A high mortality level is recorded between the 10th and 15th day after hatching. To understand the causes of this mortality, some intensive and extensive larval-breeding experiments have been carried out, between 1980-1983, using various food sequences. The influence of the breeding density and of some environmental parameters on the larval survival have been evaluated. The best results have been obtained by substituting the rotifer Brachionus plicatilis for the first few days by the ciliate Euplotes in a diet also composed of concentrated Chlamydomonas. The typical movements of Euplotes seemed to facilitate catching the prey by the juveniles. A culturing density of 4-7 larvae per liter in green water with few water exchanges, has enhanced a plankton bloom which resulted in quite satisfactory growth increments and homogeneous sizes of the larvae. From the 40th to the 70th day, frozen Artemia were fed. This acquainted the post-larvae to capture an inert prey, and facilitated the larval growth. With regard to the survival rates, it has been shown that some critical period in larval breeding occurs. The first critical period was identified to occur immediately after hatching with a mortality rate of 15%. Most probably it is caused by environmental factors and by mechanisms which regulate the population density. |
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