483
26 Current Status and Future Challenges in Cephalopod Culture
field of research in cephalopod culture. In addition, greater effort is being made to
understand the digestive capability of cephalopods, and recent results in octopuses
may be able to clarify the assimilation process and the feeding requirements during
the juvenile phase (see Chaps. 5 and 20). The acidic environment and the presence
of cathepsins (enzyme of the lineage of pepsin) in the gastric juice of O� maya juveniles have shown that artificial food for octopus, and possibly for cephalopods
in general, should have characteristics very different from those used to feed other
aquatic organisms (Martínez et al. 2011).
On the other hand, in species displaying a small-sized paralarvae after hatching
and being planktonic during this life stage, the delicate first feeding period represents a major source of mortality, where the suitability of food is suspected to be
the main factor influencing the poor survival such as for O� vulgaris (Iglesias et al.
2007; Villanueva and Norman 2008). In these cases, to go beyond the experimental
rearing that relies on natural prey, as decapod crustacean zoeae (Villanueva 1994), a
suitable enriched Artemia protocol is needed to feed the planktonic paralarvae, and
recent studies have provided encouraging results to this respect (Guinot et al. 2013,
Chap. 23). Although nutritional approaches will play an important role in improving
rearing conditions, future efforts also should focus on improving feeding rates of
paralarvae and thus their survival and growth. The mechanisms by which paralarvae
select their prey and that determine prey-capture success remain as an area of much
needed research.
26.2.2 The Control of Reproduction
After nutrition, the second main bottleneck in cephalopod culture probably is the
control of reproduction. Although most cultured species reproduce in captivity and
eggs are obtained during the spawning season, overall control over reproduction is
lacking. Cephalopods are semelparous and individuals of all coastal species tested
for culture die after spawning; thus, the broodstock must be renewed every culture
cycle. Further investigation to describe methods and establish protocols for accelerating and retarding the collection of egg masses is needed. Until now, cephalopod
egg masses are obtained by: (a) spontaneous spawning of broodstocks, (b) eggs
collected from the field and (c) in vitro fertilization. As coastal cephalopods spawn
at the end of their life cycle, experienced workers can tentatively expect the collection of egg masses in laboratory according to the existing knowledge of a given
species life cycle for a particular geographical location. This includes information
on the spawning season, behaviour and external body characteristics. However, this
method is relatively basic and sometimes subjected to high individual variation.
Studies that allow the ability to control sexual maturation and spawning entirely
are necessary to accurately obtain egg masses according to the planned culture design. Knowledge of the influence of natural variables on sexual maturation and
spawning should be clearly defined. The effect of light intensity and photoperiod
on sexual maturity has been studied in few species (Richard 1971; Zúñiga et al.
1995) and need further research. Despite the functional neuroendocrine analogy
26 Current Status and Future Challenges in Cephalopod Culture
field of research in cephalopod culture. In addition, greater effort is being made to
understand the digestive capability of cephalopods, and recent results in octopuses
may be able to clarify the assimilation process and the feeding requirements during
the juvenile phase (see Chaps. 5 and 20). The acidic environment and the presence
of cathepsins (enzyme of the lineage of pepsin) in the gastric juice of O� maya juveniles have shown that artificial food for octopus, and possibly for cephalopods
in general, should have characteristics very different from those used to feed other
aquatic organisms (Martínez et al. 2011).
On the other hand, in species displaying a small-sized paralarvae after hatching
and being planktonic during this life stage, the delicate first feeding period represents a major source of mortality, where the suitability of food is suspected to be
the main factor influencing the poor survival such as for O� vulgaris (Iglesias et al.
2007; Villanueva and Norman 2008). In these cases, to go beyond the experimental
rearing that relies on natural prey, as decapod crustacean zoeae (Villanueva 1994), a
suitable enriched Artemia protocol is needed to feed the planktonic paralarvae, and
recent studies have provided encouraging results to this respect (Guinot et al. 2013,
Chap. 23). Although nutritional approaches will play an important role in improving
rearing conditions, future efforts also should focus on improving feeding rates of
paralarvae and thus their survival and growth. The mechanisms by which paralarvae
select their prey and that determine prey-capture success remain as an area of much
needed research.
26.2.2 The Control of Reproduction
After nutrition, the second main bottleneck in cephalopod culture probably is the
control of reproduction. Although most cultured species reproduce in captivity and
eggs are obtained during the spawning season, overall control over reproduction is
lacking. Cephalopods are semelparous and individuals of all coastal species tested
for culture die after spawning; thus, the broodstock must be renewed every culture
cycle. Further investigation to describe methods and establish protocols for accelerating and retarding the collection of egg masses is needed. Until now, cephalopod
egg masses are obtained by: (a) spontaneous spawning of broodstocks, (b) eggs
collected from the field and (c) in vitro fertilization. As coastal cephalopods spawn
at the end of their life cycle, experienced workers can tentatively expect the collection of egg masses in laboratory according to the existing knowledge of a given
species life cycle for a particular geographical location. This includes information
on the spawning season, behaviour and external body characteristics. However, this
method is relatively basic and sometimes subjected to high individual variation.
Studies that allow the ability to control sexual maturation and spawning entirely
are necessary to accurately obtain egg masses according to the planned culture design. Knowledge of the influence of natural variables on sexual maturation and
spawning should be clearly defined. The effect of light intensity and photoperiod
on sexual maturity has been studied in few species (Richard 1971; Zúñiga et al.
1995) and need further research. Despite the functional neuroendocrine analogy