306
E. A. G. Vidal and S. von Boletzky
16.7.4 Cleaning Techniques
Any action likely to disturb the animals should be avoided or at least minimized.
Thus, cleaning techniques should be ‘squid friendly’. Cleaning robots moving
slowly over the walls and the bottom of tanks or sea cages may offer an optimal
approach. For such robots, circular tanks are optimal.
16.7.5 Growth, Survival, Spawning and Sampling
The right food items offered at short intervals to achieve an ad libitum regime, optimal water quality and temperature should generate high growth rates. However,
differences in individual growth rates are inevitable and may lead to increased risks
of cannibalism (small individuals being attacked by large ones).
The whole life cycle of D. opalescens was covered by Yang et al. (1986) in less
than 8 months, thus representing ‘culture’ in the strict sense of the term. Squid
exhibited exponential growth for the first 2 months of life and thereafter showed
slower logarithmic growth of 1.6 % ww day
−1
and 0.63 % mm ML day
−1
and mean
growth of 16 mm per month at 240 dah (Table 16.2). At this period, they were doubling their weight and length at every 42 days and 109 days, respectively. Mortality
slowed after 60–70 dah, and again after 180 days due to spawning. Maximum lifespan was 235 and 248 days in the two experiments conducted, with squid attaining
a maximum size of 116 mm ML. Maturity was observed at 60 mm ML in females
and 70 mm ML in males. Spawning took place between 196 and 239 dah producing viable eggs. Fin or skin damage and senescence after reproduction accounted
for late mortality. Thus, considering the aforementioned culture conditions, time to
marketable size cannot be reduced below a minimum of 4–8 months.
16.8 Trends in Research and Industrial Level
Both loliginid species considered in this chapter have been used extensively as experimental models in several research areas. Nevertheless, as indicated above, there
is no hint of a market pressure for industrial levels of culture in L. vulgaris and D.
opalescens. When considering these two species as candidates for large-scale cultures in research, it would be interesting to assess their potential in relation to that
of other loliginid species.
E. A. G. Vidal and S. von Boletzky
16.7.4 Cleaning Techniques
Any action likely to disturb the animals should be avoided or at least minimized.
Thus, cleaning techniques should be ‘squid friendly’. Cleaning robots moving
slowly over the walls and the bottom of tanks or sea cages may offer an optimal
approach. For such robots, circular tanks are optimal.
16.7.5 Growth, Survival, Spawning and Sampling
The right food items offered at short intervals to achieve an ad libitum regime, optimal water quality and temperature should generate high growth rates. However,
differences in individual growth rates are inevitable and may lead to increased risks
of cannibalism (small individuals being attacked by large ones).
The whole life cycle of D. opalescens was covered by Yang et al. (1986) in less
than 8 months, thus representing ‘culture’ in the strict sense of the term. Squid
exhibited exponential growth for the first 2 months of life and thereafter showed
slower logarithmic growth of 1.6 % ww day
−1
and 0.63 % mm ML day
−1
and mean
growth of 16 mm per month at 240 dah (Table 16.2). At this period, they were doubling their weight and length at every 42 days and 109 days, respectively. Mortality
slowed after 60–70 dah, and again after 180 days due to spawning. Maximum lifespan was 235 and 248 days in the two experiments conducted, with squid attaining
a maximum size of 116 mm ML. Maturity was observed at 60 mm ML in females
and 70 mm ML in males. Spawning took place between 196 and 239 dah producing viable eggs. Fin or skin damage and senescence after reproduction accounted
for late mortality. Thus, considering the aforementioned culture conditions, time to
marketable size cannot be reduced below a minimum of 4–8 months.
16.8 Trends in Research and Industrial Level
Both loliginid species considered in this chapter have been used extensively as experimental models in several research areas. Nevertheless, as indicated above, there
is no hint of a market pressure for industrial levels of culture in L. vulgaris and D.
opalescens. When considering these two species as candidates for large-scale cultures in research, it would be interesting to assess their potential in relation to that
of other loliginid species.