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Pikeperch (Sander lucioperca) has a high potential for inland aquaculture diversification in Europe. Bottlenecks (i.e. low survival, cannibalism and deformity rates) hamper further expansion of pikeperch culture, because of the weak production performances at the nursery level. To improve the production of pikeperch juveniles under recirculation system we used a pilot scale larval rearing system (700 L tanks) and multifactorial designs. Three successive larval rearing trials (duration: 35-49 days) were conducted to identify the best combination of environmental, feeding and population factors. Considering the main significant effects observed on survival, growth, swim bladder inflation rates and biomass gain, a favourable combination of twelve factor (F) modalities was proposed (F1- initial density: 100 larvae.L-1, F2- no sorting of fish jumper, F3- no sibling population, F4- eggs from large females, F5- discontinuous feeding, F6- no co-feeding, F7- light intensity: 50 lx, F8- beginning of the weaning at 16 dph (days post-hatching), F9- weaning duration: 9 days, F10- water renewal rate of 100 % per hour, F11- tank cleaning during morning and F12- tank bottom-up water current). A final validation step was realized over a last trial (seven replicates, duration: 49 days), and validated with the best productive results obtained over the global experimental period (2015-2018). These results were: a final body weight of 815.64 ± 95.34 mg, a survival rate of 16.9 ± 1.7 %, a specific growth rate of 15.1 ± 5.9 %.d-1, a final fish biomass of 9.55 ± 0.23 kg, a swim bladder inflation rate of 92.6 ± 3.2 % and a food conversion rate of 0.65 ± 0.02 (dry food). The final stocking density was 13.6 kg.m-3 of rearing volume. Authors were able to validate and provide a reliable basic protocol for pikeperch larval rearing using recirculating units. info:eu-repo/semantics/publishedVersion

Biology of European Seabass presents up-to-date reviews on key topics of seabass biology, written by leading scientific experts with extensive knowledge of seabass as well as their respective field of expertise. The book covers the biology and ecology of the different sea basses and the latest findings in molecular biology, physiology, and beh; International audience; Marine fish larval culture is one of the main bottlenecks in the aquaculture industry. At hatching, most of the organs of marine fish larvae are not fully developed, and developmental processes initiated during embryogenesis continue during larval development in order to ensure the proper ontogenesis of organs and associated physiological functions, essential for the survival of individuals. Consequently, during the first weeks of life, marine fish larvae undergo significant morphological and physiological modifications to acquire all the adult features by the end of the larval period. This phase is certainly the most critical in the life cycle of fish, not only in natural environments, but also under controlled conditions. In aquaculture, in spite of the many advances made to control environmental cues, this stage of production can still suffer from substantial mortality impaired larval quality, influencing the overall performance of the rearing production, whose final objective is the obtention of enough fry of good quantity and quality for on-growing purposes.

To improve the understanding of the incidence of skeletal deformities in Senegalese sole (Solea senegalensis), a feeding trial was carried out to evaluate the effect of increasing dietary arachidonic acid (ARA) levels during the Artemia feeding period on larval growth and skeletogenesis. Larvae were fed from 8 to 50 days post hatching (dph) with Artemia nauplii enriched with three different levels of ARA: ARA-Low, ARA-Medium and ARA-High (1.0, 4.5 and 7.0% ARA of total fatty acids, respectively). Increasing levels of dietary ARA did not affect significantly the survival. However, it influenced growth; larvae from the ARA-M group presented the highest values of final standard length and dry weight (11.36 +/- 0.47 mm and 5.86 +/- 1.06 mg at 50 dph, respectively) and larvae from the ARA-H group the lowest ones (9.53 +/- 0.27 mm and 2.47 +/- 0.26 mg at 50 dph). The skeleton of larvae fed the ARA-M diet tended to be more calcified at 15 dph than that of larvae fed ARA-L and ARA-H diets. Larvae from the ARA-M group tended to show a higher incidence of fusion of hypurals 3 and 4 (34.4 +/- 3.1%) at 50 dph than the larvae from the other groups (18.7 +/- 1.6%, in average). The latter results reflected a trend to a higher degree of skeletal development rather than a deformity, this being in agreement with the higher larval growth of this group. Besides, ARA levels did not affect significantly the incidence of total skeletal deformities (41.4 +/- 1.5% in average). Larvae from all dietary treatments mostly displayed fusions of the vertebra 43 and 44 (32.2 +/- 1.3% in average). The amount of 4.5% of total fatty acid of dietary ARA during Artemia feeding period promoted the best growth and proper skeletogenesis in Senegalese sole larvae.

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The presence of sublethal morphological deformities represents one of the main bottleneck of the industrial finfish hatchery production, resulting in major economic loss due to reduced growth and marketing ability of the final product, that has to be transformed (filets) or sold for fish flour. Furthermore, the elimination of deformed fishes from the productive cycle needs for periodic selections at present carried out by manual sorting. This represents an additional economic cost, and a stress for fishes. This work benefits from participation in LARVANET COST action FA0801.

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This chapter is aimed at providing a global view of Siberian sturgeons' alevin production standards, by successively indicating production systems, management standards and alimentation strategies. A recall of morphological alterations of larvaes through their development is given in annexes. When it is possible, data from other species also are indicated. Restoration and protection of Acipenser sturio is limited by the very weak availability of biological devices and therefore experimental possibilities also are limited in this field. However, we show preliminary results earned from this endangered species., Ce chapitre va s'attacher à donner une vue d'ensemble du mode de production d'alevins d'esturgeons sibériens, en indiquant successivement les systèmes de production, les modes de gestion et les stratégies d'alimentation. Un rappel des changements morphologiques que présentent les larves au cours de leur développement est donné sous forme d'annexes. Lorsque cela sera possible, les données sur d'autres espèces seront indiquées. La restauration et la sauvegarde de l'acipenser sturio se heurte à une très faible disponibilité en matériel biologique et limite donc considérablement les possibilités expérimentales dans ce domaine. Néanmoins, nous indiquerons les résultats préliminaires acquis sur cette espèce en danger.

The influence of short-term storage in coelomic fluid at 15° C of ovulated eggs of mature females from sterlet (Acipenser ruthenus) and siberian sturgeon (Acipenser baeri) was studied. The percentage of fertilization, embryonic survival, abnormally developing embryos, hatching and larvae with malformations at hatching was measured.

Behavioural modifications of Acipenser baeri were studied during early ontogeny at 18°C by means of specific tests and general observations. At 13 days p.h., the percentage of fish exhibiting positive phototactism, preferring open to concealed bottom habitats and white bottoms started to decrease, while at 20 days p.h. specimens showed a clear preference for bottom concealment and black and greyish bottoms. The significance, use and evolution of the former behavioural patterns is deeply discussed., Les résultats sont obtenus à partir de larves provenant d'une seule femelle. Cela suggère que se sont des caractéristiques spécifiques. Des tests de comportement ont permis de décrire l'évolution des préférendum des larves depuis l'éclosion jusqu'à 20j pour la lumière ou l'ombre, un habitat ouvert ou couvert et la couleur du fond. A l'âge de 20j, les alevins préfèrent un abri et des fonds gris ou noir. L'ensemble des données comportementales acquises sont discutées que ce soit vis à vis de l'élevage ou de l'écologie de l'espèce.

This thesis is focus on the early ontogenesis of the siberian sturgeon, Acipenser baeri Brandt. Morphological development and growth were described. Different stages of behaviour were defined and connected with first feeding and tentatively with ecology. The influence of egg size and time of first feeding were studied on survival and growth. The digestive tract was characterised from both aspects, histology and histochemistry., Cette thèse est focalisée sur le debut de l'ontogénese chez l'esturgeon Acipenser baeri Brandt de Siberie. Le dévelopement morphologique et la croissance sont décrit. Les différentes étapes de comportement sont définies et mise en relation avec la nourriture ingurgitée au premier repas et l'environment. L'influence de la taille des oeufs et le délai entre l'éclosion et le premier repas sur la survie et la croissance de l'esturgeon a aussi été étudiée. Le tube digestif a été caractérisé aussi bien sur son aspect histologique et histochimique.

Morphological development of Siberian sturgeon (Acipanser baeri) between hatching and metamorphosis (up to 3 weeks after hatching) was examined in hatchery-reared specimens in order to describe an useful criterion for fish farmers to estimate the quality of young specimens and detect abnormal and unsuitable rearing conditions. Morphological development was described according to morphological traits distinguishable upon external observation of specimens, such as the level of development of sensory, feeding and swimming systems, and the determination of the depletion of yolk sac and onset of exogenous feeding. Two distinct phases were observed in the morphological development of Siberian sturgeon, the prelarval stage which was comprised between hatching (10.4-11.1 mm TL) and first feeding (9-10 days post hatch, 19.7-21.6 mm TL) and the larval stage, which was between the initiation of external feeding and metamorphosis (19-20 days post hatch, 28-32 mm TL). Morphogenesis and differentiation were more intense during prelarval than larval development. Hatchlings and prelarvae had rudimentary sensory and locomotor systems. During prelarval development these systems developed greatly, and at the beginning of the larval stage, their development was almost finished. At the end of the larval phase, specimens resembled a miniature adult. The structure and morphological development of Siberian sturgeon during prelarval and larval ontogeny were quite similar to other Acipenserid species, and some differences were detected in relation with the age at which morphological changes took place, as a consequence of different rates of development and rearing temperatures.

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