459
24 Octopus vulgaris: Ongrowing
productive value (Cerezo Valverde et al. 2012b). The better feed efficiency of diets
with a moderate lipid content (6–9 % wet weight) compared with low lipid diets
(< 2 %) has been demonstrated (Estefanell et al. 2011; Cerezo Valverde et al. 2012b).
Krill, fish and crab meals did not give good results as regards acceptability or growth
(Estefanell et al. 2009; López et al. 2009; García-Garrido et al. 2010a). The tendency
now is to work without fresh ingredients in favour of dry, preferably freeze-dried
ones (Morillo-Velarde et al. 2012b, 2013) and to manufacture extruded feeds with a
composition that differs from granulated fish feed (Querol et al. 2012a, b).
24.5 Culture Yield: Growth and Survival
The growth and survival results obtained in different ongrowing experiments in
floating cages and tanks (Table 24.1) and their variability have been related, as
mentioned above, with factors such as water temperature, culture density, size dispersion, the reproduction season and the type of feed supplied. However, erring on
the conservative side, it can be concluded that under optimal culture conditions a
production cycle in which the octopuses grow from 750 to 3,500 g can be carried
out in 90–120 days with a survival rate of 80–90 %. This means that up to three
production cycles per year are possible although this depends on the geographical
position of the installations and, in particular, on the temperature. In the Mediterranean, sea temperatures are very high for this species (exceeding 20–24 °C) so
that production is only viable between mid-October and mid-June, as demonstrated
experimentally (García García et al. 2009) in offshore cages (Fig. 24.2). In Galicia,
on the other hand, it is the low temperatures of winter that limit culture, so that here,
too, only two cycles are possible. In areas like the Canary Islands where the water
temperature varies very little around 18–20 °C, three cycles are possible although
this has not been demonstrated experimentally. Three cycles are also possible in
tanks equipped with recirculation systems and temperature control.
24.6 Conclusions
There is enough information to establish in a general way and with certain degree of
reliability optimum conditions for ongrowing process to O� vulgaris. Unfortunately,
much of that information is available only for conference papers. Thus, specific and
rigorous studies are still needed both for the influence of environmental parameters
as to establish the optimum parameters of the culture in each geographical area and
for different production systems (land tanks or sea cages: protected areas, offshore
and benthic). Exhaustive studies on the biochemistry of cephalopods, their natural diets and different raw material have led to great advances in our understanding of their nutritional requirements. With semi-humid formulated diets moderate
growth rates have been achieved, similar to when a fish-based diet is supplied.
24 Octopus vulgaris: Ongrowing
productive value (Cerezo Valverde et al. 2012b). The better feed efficiency of diets
with a moderate lipid content (6–9 % wet weight) compared with low lipid diets
(< 2 %) has been demonstrated (Estefanell et al. 2011; Cerezo Valverde et al. 2012b).
Krill, fish and crab meals did not give good results as regards acceptability or growth
(Estefanell et al. 2009; López et al. 2009; García-Garrido et al. 2010a). The tendency
now is to work without fresh ingredients in favour of dry, preferably freeze-dried
ones (Morillo-Velarde et al. 2012b, 2013) and to manufacture extruded feeds with a
composition that differs from granulated fish feed (Querol et al. 2012a, b).
24.5 Culture Yield: Growth and Survival
The growth and survival results obtained in different ongrowing experiments in
floating cages and tanks (Table 24.1) and their variability have been related, as
mentioned above, with factors such as water temperature, culture density, size dispersion, the reproduction season and the type of feed supplied. However, erring on
the conservative side, it can be concluded that under optimal culture conditions a
production cycle in which the octopuses grow from 750 to 3,500 g can be carried
out in 90–120 days with a survival rate of 80–90 %. This means that up to three
production cycles per year are possible although this depends on the geographical
position of the installations and, in particular, on the temperature. In the Mediterranean, sea temperatures are very high for this species (exceeding 20–24 °C) so
that production is only viable between mid-October and mid-June, as demonstrated
experimentally (García García et al. 2009) in offshore cages (Fig. 24.2). In Galicia,
on the other hand, it is the low temperatures of winter that limit culture, so that here,
too, only two cycles are possible. In areas like the Canary Islands where the water
temperature varies very little around 18–20 °C, three cycles are possible although
this has not been demonstrated experimentally. Three cycles are also possible in
tanks equipped with recirculation systems and temperature control.
24.6 Conclusions
There is enough information to establish in a general way and with certain degree of
reliability optimum conditions for ongrowing process to O� vulgaris. Unfortunately,
much of that information is available only for conference papers. Thus, specific and
rigorous studies are still needed both for the influence of environmental parameters
as to establish the optimum parameters of the culture in each geographical area and
for different production systems (land tanks or sea cages: protected areas, offshore
and benthic). Exhaustive studies on the biochemistry of cephalopods, their natural diets and different raw material have led to great advances in our understanding of their nutritional requirements. With semi-humid formulated diets moderate
growth rates have been achieved, similar to when a fish-based diet is supplied.