Growth and mortality of common octopusOctopus vulgarisreared at different stocking densities in Mediterranean offshore cages

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.

Comparison Between Individual and Group Rearing Systems in Octopus vulgaris (Cuvier, 1797)

“…Despite the negative effect on survival, the traditional group rearing system had a positive effect on growth and final weight, especially noticeable in males, probably related to the stimulation of food intake, producing better biomass increment and A‐FCR than individually reared specimens until the 40–50th d of rearing. This finding underlines that traditional group rearing system could be more profitable than individual rearing if mortality can be reduced, for example, with periodic grading, which should reduce weight dispersion during the ongrowing cycle (Socorro et al 2005; García García et al 2009). Also, present results underlined the negative effect of breeding behavior on O. vulgaris biological performance, especially in females.…”

“…Particularly in Trial 1, low growth rates observed in females and the presence of egg masses evidenced reproductive behavior (Iglesias et al 2000), which is associated to the end of O. vulgaris life cycle in both sexes (Estefanell et al 2010). Also, different growth rate and final weight between sexes led to high weight dispersion, which also increases mortality in O. vulgaris under rearing conditions, due to hierarchical behavior and cannibalism (Socorro et al 2005; García García et al 2009). As a result, mortality in this trial could have been related to reproductive processes, to interaction among octopuses or to a combination of both.…”

“…Indeed, octopus industrial farming is carried out in floating cages provided with shelters (Chapela et al 2006; Rodríguez et al 2006). Particularly in O. vulgaris , mortality under rearing conditions is associated to hierarchical behavior, cannibalism, and reproductive processes (García García et al 2009; Estefanell et al 2010). In contrast, high survival rates were observed in octopuses reared in confinement in individual tanks (Petza et al 2006; García García and Cerezo Valverde 2006; Miliou et al 2007; García Garrido et al 2011) or in individual net cages placed inside tanks (400–1000 L) (Biandolino et al 2010; Estefanell et al 2009; Prato et al 2010).…”

Performance of raw material thermal treatment on formulated feeds for common octopus (Octopus vulgaris) ongrowing

“…The common octopus (Octopus vulgaris) has aroused great interest in recent years as a new species for aquaculture because of its high appreciation by consumers, a broad international market and attractive selling prices, and potential for offshore aquaculture García García et al, 2009;Vaz-Pires et al, 2004). Nonetheless, the development of a sustainable artificial diet is still considered a bottleneck in O. vulgaris culture (Sánchez et al, 2014) and understanding the species physiology and nutrition will probably be the biggest challenge in developing the large scale culture of the species on a medium to long-term (Villanueva et al, 2014).…”

Biological performance ofOctopus vulgarisin ‘integrated aquaculture’ models: effect of two potential fresh diets, sex and sexual maturation during the grow-out phase

“…In contrast, several authors reported a high biological performance in males and females of O. vulgaris reared together in floating cages (Rodríguez et al . ; García García, Cerezo Valverde, Aguado‐Giménez, García García & Hernández ).…”