Progress in larviculture of the Atlantic halibut Hippoglossus hippoglossus
Lein, I.; Gulbrandsen, J.; Holmefjord, I.; Refstie, T.; Bolla, S.; Olsen, Y.; Reitan, K.I.; Vadstein, O.; Øie, G.; Harboe, T.; Sorgeloos, P. (1992). Progress in larviculture of the Atlantic halibut Hippoglossus hippoglossus. Mededel. Fac. landb. wet. Rijksuniv. Gent 57(4b): 2099-2110
In: Mededelingen van de Faculteit Landbouwwetenschappen. Rijksuniversiteit Gent. Faculteit Landbouwwetenschappen: Gent. ISSN 0368-9697, more
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| Keywords |
Hippoglossus hippoglossus (Linnaeus, 1758) [WoRMS]
Marine/Coastal |
| Authors | | Top |
- Lein, I.
- Gulbrandsen, J.
- Holmefjord, I.
- Refstie, T.
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- Bolla, S.
- Olsen, Y.
- Reitan, K.I.
- Vadstein, O.
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- Øie, G.
- Harboe, T.
- Sorgeloos, P., more
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| Abstract |
The main goal of the project is to develop intensive industrial scale production systems for halibut fry. Halibut eggs were obtained from three brood stocks both by stripping and by natural spawning. Photoperiod manipulation is used to increase the spawning period, and spawning now takes place in the period February to June/July. The eggs are disinfected and incubated in up-stream conical tanks (8°C, darkness) and transferred to larval incubators after hatching. Two incubator-types are used; small glass bowls (3 liter), run stagnant or semi-stagnant, or large conical silos (0.7-15m³) run with continuous water flow (4-8°C, darkness). These different systems can be used to bring the yolk sac larvae of halibut up to the stage of first feeding. The yolk sac phase lasts for 35-50 days dependent of the temperature, and the larvae are very sensitive to physical conditions (light, temperature, water currents) and the environmental microbial community during this development stage. The survival averages 80% (for adequate groups) in small bowls and 50-70% in large flow-through silo incubators.Adjustment of the light conditions is presently among the main challenges in halibut first feeding. The larvae are positively attracted by all light qualities and dense schooling in the surface of the tank is a frequent observation. Such behaviour will result in extensive mortality in a matter of a week, and must in all events be avoided. Use of submerged light or strong sublight, which has been reduced to 30% intensity by appropriate filters, combined with algal addition to the fish tanks have yielded adequate behavioural response and in turn positive feeding results, but the mechanisms are not adequately understood so far.The rotifer Brachionus plicatilis and Artemia enriched by long chain omega3 fatty acids by use of emulsified lipid diets (Selco-type, Artemia Systems SA, Belgium) have been used as live feed for the halibut larvae. The rotifers are normally used during the first 10-15 days, but attempts have been made to use small Artemia instead of the rotifer. Larger on-grown Artemia has been used after 3-4 weeks of feeding. Addition of microalgae to the fish tanks enhance both growth rate and survival through the phase of the first feeding. The larvae increase their body weight by approximately 10% per day in the initial phase (13°C), provided that adequate diets are used. Weaning may be started beyond day 50 after the start of first feeding, and metamorphosis will occur at the same time. Survival up to 20% has been obtained so far. |
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