153
9 Farming Costs and Benefits, Marketing Details, Investment Risks
water temperature range and variation, one or two fattening cycles may be completed in the Mediterranean and up to three in open sea in the Atlantic area.
Water temperature is the greatest conditioning factor in octopus growth. Trials
in tanks and cages in the Mediterranean have shown that the best performance is
obtained between 16 and 21 °C, with mortality notably increasing at temperatures
above 22 °C (Aguado Giménez and García García 2002; García García et al. 2009).
The open sea locations of the Northwest Atlantic in the Galician coast exhibit ideal
conditions for O� vulgaris, having a growing temperature within the optimal range
indicated. However, this process commonly occurs inside the Galician estuaries,
where the annual temperature ranges from 12 to 19 °C, and therefore it is not within
the optimum range all year round. In the Mediterranean, the temperature varies
widely from 10 to 14 °C in winter and in the range of 25–27 °C in summer; therefore, the fattening activities of this species is restricted to about 7–8 months per
year, specifically between October and June (García García et al. 2009).
Survival is one of the production parameters that varies most according to diverse factors, notably the load, size dispersion, type of food supplied, descents in salinity by rainfall or in locations next to river mouths. Under optimum conditions, the
survival for a production process could be around 80 % (Rey-Méndez et al. 2003;
Alemany 2011; García García et al. 2004b).
9.2.4 Feeding
Most of the ongrowing octopus experiments use similar foodstuff, fundamentally
fishery discards, particularly crustaceans, fishes and bivalve molluscs. However,
the best performance in terms of growth and food conversion index (CI) has been
obtained with mixed diets of crab ( Carcinus mediterraneus) and bogue ( Boops boops; García García and Cerezo Valverde 2006). According to the initial and final
sizes measured in the ongrowing process at the different stages tested, several survival values and indexes of real conversion were calculated; these results are to be
taken into account because of the extra cost that they suppose (Oltra et al. 2005;
García García et al. 2004a). In any case, and as already mentioned, to develop the
industrial ongrowing of O� vulgaris and obtain a satisfactory performance of the
whole process, a specific commercial diet is necessary that has not yet been developed (Lee 1994; Vaz-Pires et al. 2004; Cerezo Valverde et al. 2008).
9.3 Costs Analysis
9.3.1 Initial Investment
The initial investment in the octopus culture structures is very high when compared
with intensive fish farming, both on land and in floating sea cages. This may be
9 Farming Costs and Benefits, Marketing Details, Investment Risks
water temperature range and variation, one or two fattening cycles may be completed in the Mediterranean and up to three in open sea in the Atlantic area.
Water temperature is the greatest conditioning factor in octopus growth. Trials
in tanks and cages in the Mediterranean have shown that the best performance is
obtained between 16 and 21 °C, with mortality notably increasing at temperatures
above 22 °C (Aguado Giménez and García García 2002; García García et al. 2009).
The open sea locations of the Northwest Atlantic in the Galician coast exhibit ideal
conditions for O� vulgaris, having a growing temperature within the optimal range
indicated. However, this process commonly occurs inside the Galician estuaries,
where the annual temperature ranges from 12 to 19 °C, and therefore it is not within
the optimum range all year round. In the Mediterranean, the temperature varies
widely from 10 to 14 °C in winter and in the range of 25–27 °C in summer; therefore, the fattening activities of this species is restricted to about 7–8 months per
year, specifically between October and June (García García et al. 2009).
Survival is one of the production parameters that varies most according to diverse factors, notably the load, size dispersion, type of food supplied, descents in salinity by rainfall or in locations next to river mouths. Under optimum conditions, the
survival for a production process could be around 80 % (Rey-Méndez et al. 2003;
Alemany 2011; García García et al. 2004b).
9.2.4 Feeding
Most of the ongrowing octopus experiments use similar foodstuff, fundamentally
fishery discards, particularly crustaceans, fishes and bivalve molluscs. However,
the best performance in terms of growth and food conversion index (CI) has been
obtained with mixed diets of crab ( Carcinus mediterraneus) and bogue ( Boops boops; García García and Cerezo Valverde 2006). According to the initial and final
sizes measured in the ongrowing process at the different stages tested, several survival values and indexes of real conversion were calculated; these results are to be
taken into account because of the extra cost that they suppose (Oltra et al. 2005;
García García et al. 2004a). In any case, and as already mentioned, to develop the
industrial ongrowing of O� vulgaris and obtain a satisfactory performance of the
whole process, a specific commercial diet is necessary that has not yet been developed (Lee 1994; Vaz-Pires et al. 2004; Cerezo Valverde et al. 2008).
9.3 Costs Analysis
9.3.1 Initial Investment
The initial investment in the octopus culture structures is very high when compared
with intensive fish farming, both on land and in floating sea cages. This may be