Effect of sex ratio on growth and survival in Octopus vulgaris (Cuvier, 1797) reared in floating cages

[EN]Octopus vulgaris is a potential candidate to diversify European aquaculture for its rapid growth and high market prices (Vaz Pires et al. 2004). One factor affecting industrial development of octopus culture is sexual maturation under rearing conditions. Octopus females can lose up to 30-60% of their initial body weight during egg-laying (Iglesias et al., 2000) and die after the paralarvae hatch (Guerra,1992), while a correlation between males death and spermatic sac depletion has being recently reported by Estefanell et al. (2010b). The present experiment discusses the effect of three different sex ratios on growth, sexual maturation and survival in O. Vulgaris. Conclusions: Discarded bogue from fish farms could be used as alternative diet for the final stage of O. vulgaris ongrowing ; Male segregation would maximize biomass increment ; Under the conditions described, sex ratios close to 1:1 produced higher biomass increment than 4:1

Engorde de pulpo (Octopus vulgaris) alimentado exclusivamente con boga (Boops boops) de descarte de la acuicultura

[EN] The use of low value fish (Bogue, Boops boops), accidentally reared in seabream culture cages, as a sole food in octopus farming was tested in two different experiments located in Canary Islands. In a first experiment two different initial sizes were compared: 1,5 kg & 2,3 kg, both at a density of 11 kg/m3. Initial density was increased in a second experiments to 16 kg/m3 testing two lower initial weights: 1,0 kg & 0,8 kg. Bogue as a single feed was found to be good enough to sustain a good growth in octopus cage rearing. Best growth in terms of specific growth rate and average daily growth was obtained with the lowest grow size, 0,8 kg.

Growth and fatty acid composition of Octopus vulgaris fed different diets based on bogue (Boops boops) in comparison to wild individuals

[EN] Octopus vulgaris is a suitable candidate to diversify marine aquaculture (Iglesias et al., 2000; Vaz Pires et al. 2004). Actually, wild sub-adults are on-growing in floating cages showing promising results (Chapela et al., 2006; Rodríguez et al., 2006). Even though octopus industrial development is still limited, mainly associated to the dependence of wild catch individuals for ongrowing (Iglesias et al., 2007) and a lack of an appropriate formulated diet (García García and Cerezo, 2006). In addition, essential macronutrient requirements for this species are still not well known. Used of discarded bogue as single food for Octopus on-growth results in similar growth than co-fed diets with the crab (Portunus pelagic). FA content of Muscle and DG showed important ARA content, suggesting the important functions of this FA in this specie.

Engorde de pulpo común Octopus vulgaris en jaulas en la comunidad Canaria [Material gráfico] [Recurso electrónico] : efecto de la dieta y la densidad inicial

Octopus vulgaris on-growing in floating cages is a promising activity implemented in Spain at industrial level, with productions of 16-32 tons/year from 1998. Nevertheless, some aspects of the culture system need to be evaluated to warrantee its profitability. In the present work absolute growth rate (AGR, g/day) and mortality (%) under two initial rearing densities, 10 and 17 kg/m3, were compared under two feeding regimes over 15 weeks. One diet was composed by bogue, supplied as ?discarded? species from local fish farms. The other diet was based on a 40-60% discarded bogue-crab Portunus pelagicus. Half of the reared octopuses were PIT-tagged and two sampling points were established along the experimental period. Regardless of dietary treatment, up to the 11th week, growth was 19 and 13 g./day for the low and high rearing density. On the other hand, up to the 11th week mortality was higher in the control diet fed group (30%), reaching 74-84% by the end of the experiment regardless of rearing density and dietary treatment, which could suggest some nutritional imbalance of the tested diets.

Evaluación de 2 sistemas de cultivo en pulpos macho Octopus vulgaris: efecto de la talla inicial y de la dieta

[EN]Octopus vulgaris on-growing in floating cages has shown promising results. Nevertheless, some aspects of the culture system need to be evaluated to warrantee its profitability. In the present work individual and group rearing, in PVC net compartments and floating cages respectively, are compared under two dietary treatments. One diet is composed by bogue, supplied as ?discarded? species from local fish farms, and the other is based on a 40-60% discarded bogue-crab Portunus pelagicus. Besides, the effect of initial size is also evaluated. All octopuses were PIT-tagged and the experiment lasted 2 months. Absolute growth rate (AGR, g./day) and mortality (%) were calculated. Control diet generated higher growth rates and lower mortality which suggests different crab requirements at higher rearing temperatures. High mortality recorded in individual rearing could be related with high initial rearing density and temperatures.

Evaluación de 2 sistemas de cultivo en pulpo común Octopus vulgaris en jaulas en la comunidad Canaria

Octopus vulgaris on-growing in floating cages is a promising activity implemented in Spain at industrial level, with productions of 16-32 tons/year from 1998. Nevertheless, some aspects of the culture system need to be evaluated to warrantee its profitability. In the present study two rearing systems and two dietary treatments were evaluated. Individual and group rearing, in PVC net compartments and floating cages respectively, were compared under two dietary treatments. One diet was composed by bogue, supplied as ?discarded? species from local fish farms, and the other was based on a 40-60% discarded bogue-crab Portunus pelagicus. All octopuses were PIT-tagged and the experiment lasted two months. Animals were sampled once throughout the experimental period and absolute growth rate (AGR, g./day) and mortality (%) were calculated. AGR of group rearing was above 30 g./day, however individual rearing showed 100% survival so biomass increment was higher. On the other hand, males grew more than females regardless of dietary treatment.

Utilización de cangrejo y harinas en un pienso para pulpo común Octopus vulgaris

The present work evaluates whether the addition of 2 species of crab (Portunus pelagicus and Grapsus grapsus) as attractants (10%) in experimental moist diet based in discarded bogue (Boops boops) may increase ingestion and growth in O. vulgaris. Besides, another diet based on flour, made from discarded bogue and G. grapsus, was tested. Finally, a 40-60% discarded bogue-crab P. pelagicus was provided as a control diet. Four male octopuses, kept The present work evaluates whether the addition of 2 species of crab (Portunus pelagicus and Grapsus grapsus) as attractants (10%) in experimental moist diet based in discarded bogue (Boops boops) may increase ingestion and growth in O. vulgaris. Besides, another diet based on flour, made from discarded bogue and G. grapsus, was tested. Finally, a 40-60% discarded bogue-crab P. pelagicus was provided as a control diet. Four male octopuses, kept in PVC net cages in the same tank, were fed each diet for 8 weeks and several parameters were calculated: absolute growth rate (AGR, g./day), standard feeding rate (SFR, %/day) and feed efficiency (FE). The addition of crab to the diet under the conditions described did not improve ingestion, growth or feed efficiency in this species, while the flour based diet generated negative growth.