Growth and mortality of common octopus Octopus vulgaris reared at different stocking densities in Mediterranean offshore cages |
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Authors: | Benjamí n Garcí a Garcí a,Jesú s Cerezo Valverde,Felipe Aguado-Gimé nez,José Garcí a Garcí a,& Marí a D Herná ndez |
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Affiliation: | IMIDA-Acuicultura, Consejería de Agricultura y Agua de la Región de Murcia, Puerto de San Pedro del Pinatar, San Pedro del Pinatar, Murcia, Spain |
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Abstract: | Four ongrowing cycles of common octopus ( Octopus vulgaris ), each with two stocking densities, were carried out in an offshore area in order to evaluate the effect of the following variables on growth ( G , % body weight day−1) and mortality ( M , % day−1): weight ( W , 0.5–3.0 kg), temperature ( T , 14–26 °C), stocking density (SD, 6–46 kg m−3), size dispersion, expressed as coefficient of variation (CV, 13–42%) and significant wave height (SWH: 0.4–1.2 m). The assays were performed in an 8 m3 stainless-steel floating cage divided into two compartments of 4 m3 each. For the range of temperatures considered (14–26 °C), G depended significantly on T and SWH, with maximum G values being obtained at 18.5 °C and with an important negative effect of SWH. M depended significantly on T, W and CV, mortality being minimal at 18 °C. The two other variables had an antagonistic effect, mortality increasing with greater size dispersion – suggesting that animals should be graded throughout the process – although the effect diminished as the sizes increased. The results point towards two alternatives for the commercial ongrowing of octopus under the particular conditions of the present study: (A) two ongrowing cycles of 3.5 months to reach a final weight of 2.5 kg or (B) one 5-month cycle to reach a final weight of 3.5 kg. |
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Keywords: | Octopus vulgaris ongrowing Mediterranean offshore cages mortality size dispersion |
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