276
E. A. G. Vidal and S. von Boletzky
1989) and a complementary assortment of sensory inputs are offered in captivity,
the question remains whether these highly active, gregarious animals can be fully
acclimatized to captivity without losing significant elements of their natural behaviours (cf. Zeidberg 2008). Only if ethological aspects are clearly outside the scope
of the research field envisaged, can the question of possibly impoverished behavioural repertoires be ignored in a squid culture (cf. Yang et al. 1986). Little is known
about how broodstock feeding affects eggs and paralarval quality in squid. Ideally,
females should be maintained under controlled conditions that match those to which
they have been exposed in the wild.
16.3.1 Food Supply
Considering wild food sources of squid (mainly living marine fish and shrimp), the
question of food supply in captivity raises some practical and economic problems:
Are the prey species known from wild squid stomach contents available, and if so,
can their procurement be afforded by the squid culturist? What are the acceptable
alternatives, e.g. other marine prey items or fresh water animals? Can live prey be
replaced by dead animals or food preparations? These questions again relate to the
problem of behavioural repertoires mentioned above (Boletzky 2004).
Tardent (1962) indicated for L. vulgaris kept in the Naples Aquarium that ‘cut
dead sardines and anchovies’ and live prawns ‘Leander and Lysmata (are) given at
least once a day’. In particular, this author observed that ‘food is as readily picked
up from the bottom or walls of the tank as from the water surface’. Bentivegna
(1987) confirmed these observations.
Pierce et al. (1994) summarized information on diets of wild L. vulgaris from
Scotland, northwestern Spain, western and southern Portugal and the western Mediterranean, and found fish, crustaceans, cephalopods and polychaetes in various
combinations.
For D. opalescens, Fields (1965) summarized his observations and literature surveys: ‘Thus L. opalescens probably eats two or more meals each day, foraging from
the sea surface to its floor, and any available animals of appropriate size may be its
prey. Pelagic crustaceans and fellow squid are important components of its diet; it
feeds with, and probably upon, sardines ( Sardinops caeruleus), herring ( Clupea
pallasi), mackerel ( Scomber diego), sauries ( Cololabis saira), and anchovies ( Engraulis mordax)’. The observation that ‘fellow squid’ are regularly eaten raises the
question whether cannibalism could be ‘exploited’ in squid cultures (e.g. in ‘sacrificing’ small, immature males).
16.3.2 Sex Ratio
Although the sex ratio appears to be on an average roughly 1:1 in loliginid squids, a
special situation arises with ’sneaker mating’, a phenomenon also observed in other
E. A. G. Vidal and S. von Boletzky
1989) and a complementary assortment of sensory inputs are offered in captivity,
the question remains whether these highly active, gregarious animals can be fully
acclimatized to captivity without losing significant elements of their natural behaviours (cf. Zeidberg 2008). Only if ethological aspects are clearly outside the scope
of the research field envisaged, can the question of possibly impoverished behavioural repertoires be ignored in a squid culture (cf. Yang et al. 1986). Little is known
about how broodstock feeding affects eggs and paralarval quality in squid. Ideally,
females should be maintained under controlled conditions that match those to which
they have been exposed in the wild.
16.3.1 Food Supply
Considering wild food sources of squid (mainly living marine fish and shrimp), the
question of food supply in captivity raises some practical and economic problems:
Are the prey species known from wild squid stomach contents available, and if so,
can their procurement be afforded by the squid culturist? What are the acceptable
alternatives, e.g. other marine prey items or fresh water animals? Can live prey be
replaced by dead animals or food preparations? These questions again relate to the
problem of behavioural repertoires mentioned above (Boletzky 2004).
Tardent (1962) indicated for L. vulgaris kept in the Naples Aquarium that ‘cut
dead sardines and anchovies’ and live prawns ‘Leander and Lysmata (are) given at
least once a day’. In particular, this author observed that ‘food is as readily picked
up from the bottom or walls of the tank as from the water surface’. Bentivegna
(1987) confirmed these observations.
Pierce et al. (1994) summarized information on diets of wild L. vulgaris from
Scotland, northwestern Spain, western and southern Portugal and the western Mediterranean, and found fish, crustaceans, cephalopods and polychaetes in various
combinations.
For D. opalescens, Fields (1965) summarized his observations and literature surveys: ‘Thus L. opalescens probably eats two or more meals each day, foraging from
the sea surface to its floor, and any available animals of appropriate size may be its
prey. Pelagic crustaceans and fellow squid are important components of its diet; it
feeds with, and probably upon, sardines ( Sardinops caeruleus), herring ( Clupea
pallasi), mackerel ( Scomber diego), sauries ( Cololabis saira), and anchovies ( Engraulis mordax)’. The observation that ‘fellow squid’ are regularly eaten raises the
question whether cannibalism could be ‘exploited’ in squid cultures (e.g. in ‘sacrificing’ small, immature males).
16.3.2 Sex Ratio
Although the sex ratio appears to be on an average roughly 1:1 in loliginid squids, a
special situation arises with ’sneaker mating’, a phenomenon also observed in other