|Management of a module for sole eggs production (Abstract)|
Lenzi, M.; Salvatori, R. (1989). Management of a module for sole eggs production (Abstract), in: De Pauw, N. et al. (Ed.) Aquaculture: a biotechnology in progress: volume 1. pp. 549
In: De Pauw, N. et al. (Ed.) (1989). Aquaculture: a biotechnology in progress: volume 1. European Aquaculture Society: Bredene, Belgium. ISBN 90-71625-03-6. 1-592 pp., more
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During the experiments to induce reproduction and larval culture of the sole ( Solea solea Fowler), carried on for 4 years, the best results with regard to high quality and quantity of the eggs, obtained at required times, have been obtained by stocking breeders, rather than by capturing breeders in the sea or in the Orbetello Lagoon. The breeders were stocked in two 9.5m² cement basins, with water replacement from the bottom flowing by a perforated tube bundle immersed in the sand. Water flows out at the surface, into the tube in the middle of the basin, on which a nylon net-basket of 500-600m mesh holds the planktonic eggs. The soles in the basins were between 1 and 8 years of age and fed fresh mussel meat, during the reproductive period, and this frozen food, during the pause reproductive activity, at the rate of 5.6g.d.kg-1 sole. The density was 4.5-6 individuals.m-2, corresponding to 1.2-1.5kg.m-2, which is the highest density allowed under summer temperatures. The water of a canal was used and had variabie chemical and physical characteristics depending on the tide. The annual temperatures varied between 5 and 28°C. Hypothermal salt pit water (25°5"9'; 37°/oo s) mitigated the lowest winter temperatures. During the first years of experiments, eggs were obtained by hormonal treatment of the fish with well developed gonads. Later on, conditioning experiments based upon temperature variations allowed "spontaneous" spawning and to obtain eggs continuously from October to June, with a pause during the hottest months only. The best results, on eggs quality, were obtained with specimens which had been subjected to even a short cold period (8-12°C), compared to fish kept continuously at autumnal temperatures (14-17°C) during the whole winter. During 1986, 19.20kg of soles (total starting weight) have "spontaneously" produced 10.10kg of eggs (fertilized for 60-70%), their weight increased with 42% after 9 months, and a food conversion of 16% was obtained.