L'aquaculture a-t-elle le potentiel pour devenir la « biotechnologie bleue » dans l'avenir?

L'aquaculture est passée d'une contribution insignifiante de moins de 10 % de la quantité de produits aquatiques destinés à la consommation humaine dans les années 1970 à environ 50 % à l'heure actuelle. Les attentes sont élevées pour couvrir d'autres besoins dans l'avenir alors que les captures de la pêche stagnent et que les besoins de l'homme augmentent. Cet article passe en revue l'état de l'aquaculture, son expansion d'une production destinée à satisfaire une demande locale à une demande commerciale mondialisée, et examine comment l'approche empirique des besoins du passé doit être complétée par la science et la technologie, non seulement pour répondre aux attentes mais aussi pour rendre la production aquacole plus écologique et durable. Ce document est établi à partir d'une évaluation des besoins pour le développement durable préparée pour la Conférence mondiale de la FAO sur l'aquaculture (septembre 2010, Phuket, Thaïlande)

The use of algal substitutes and the requirement for live algae in the hatchery and nursery rearing of bivalve molluscs: an international survey

The mass-production of micro-algae has been recognized by several authors as the main bottle-neck for the culture of bivalve seed. This has prompted a search for alternatives to on-site algal production, such as dried heterotrophically-grown algae, preserved algal pastes, micro-encapsulated diets, and yeasts. However the extent to which these products have been tried, and rejected or retained by hatchery operators is poorly documented. Also, the actual algal requirement and production cost of the bivalve seed industry is difficult to estimate.The present inquiry allowed the collection of data concerning the requirement of live algae and its associated costs encountered in 50 commercial and experimental hatcheries from all over the world. Furthermore, the hatchery operators were questioned about their experience with alternatives for live algae, the quality and quantity of hatchery produced algae and bivalve seed, and the employment of this sector in aquaculture.The capacity of the algal production facilities ranged between 1 m³ for a few research laboratories to nearly 500 m³ for one commercial hatchery. The total algal production capacity reported by 37 hatcheries amounted to about 500 m³ algal culture day-1, which is equivalent to about 50 kg of dry biomass. The total cost of algal production in 1990 reported by 20 hatcheries approximated US $700,000 and averaged about 30$50 to 400 per kg dry weight.About a third of the questioned operators considered algal production as a limiting factor in the rearing of bivalve seed, whereas over 50% planned an expansion of the algal cultures and more than 90% was interested in the use of suitable artificial diet. The large interest for alternatives for on-site algal production was further demonstrated by the fact that more than 50% of the operators claimed to have experimented with artificial diets. Despite the extensive research efforts, artificial diets are rarely applied in the routine process of bivalve seed production and are mostly considered as a useful backup diet

International study on <i>Artemia</i>: 14. Growth and survival of <i>Artemia</i> larvae of different geographical origin in a standard culture test

For characterization of strains of the brine shrimp Artemia of different geographical origin, a standard culture test has been developed in order to compare statistically growth and survival of larvae of different strains. 25 geographical strains have been studied so far -including, for 3 strains, analyses of cysts harvested at different times. Important differences in rates of growth and survival were observed between strains but not among batches of the same strain. Best performances were noted for strains from Bahia Salinas (Puerto Rico), Buenos Aires (Argentina), Chaplin Lake (Canada), Great Salt Lake (Utah, USA), Galera Zamba and Manaure (Colombia)

International study on <i>Artemia</i> : 24. Cold storage of live <i>Artemia</i> nauplii from various geographical sources: potentials and limits in aquaculture

Freshly-hatched Artemia nauplii from various geographical sources survived storage in a refrigerator (2-4°C) at densities of 2000 per ml and above. Except for Artemia from Chaplin Lake and Buenos Aires, naupliar viability was very high even after 48 h storage, and did not decrease significantly after a 24 h post-storage transfer to 25°C. Neither the naupliar dry weight nor biochemical composition changed significantly during refrigeration for most strains tested. Comparative culture-tests with stored and freshly-hatched nauplii as food for juvenile marine mysids Mysidopsis bahia M. and larval carp Cyprinus carpio L. revealed similar production performances

International study on <i>Artemia</i> : 32. Combined effects of temperature and salinity on the survival of <i>Artemia</i> of various geographical origin

The brine shrimp inhabits geographically isolated biotopes with specific biotic and abiotic conditions. This has resulted in various geographical strains between which marked genetica, biological and chemical differentiation exists. The response of 13 different Artemia strains to the combined effect of temperature and salinity has been studied. Experimental temperatures tested ranged from 18 to 34°C and salinities from 5 to 120 promille. Except for Chaplin Lake (Canada) Artemia , all strains showed high survival over a wide range of salinities (35-110 promille). For all strains the common temperature optimum was between 20 and 25°C. Interaction between temperature and salinity was negligible or very limited. Substantial differences in tolerance were recorded in particular at the lower end of the range of experimental salinities and at the upper end of the range temperatures. Resistance to high temperature seems to be related to the genetic classification of the Artemia strains in different sibling species. Differences, however, also exist among strains from the same sibling species. Genetic adaptation to high temperature seems to take place in Artemia . The data obtained provide a first guideline for strain selection for specific aquacultural purposes

International study on <i>Artemia</i> (1). XVII. Energy consumption in cysts and early larval stages of various geographical strains of <i>Artemia</i>

Variations in dry weight, caloric content and ash content during cyst hatching and early larval development have been studied for various geographical strains of Artemia. In general, decapsulated cysts contain 30 to 40 % more energy than freshly hatched nauplii; for Chaplin Lake and Buenos Aires Artemia this difference amounts to 57 %. Ash contents increase as decapsulated cysts hatch into instar I and molt into instar II-III nauplii. Over a 24 h larval developmental period individual dry weights and energy contents of the nauplii decrease with 16-34 % and 22-37 % respectively.A small but significant correlation exists between the survival rate of starved nauplii and either the energy content of instar I and instar II-III nauplii or the proportional energy consumption during metabolism from decapsulated cysts to instar II-III nauplii. The potential impact of these results on the use of Artemia in aquaculture hatcheries is discussed

Technological improvements for the cultivation of invertebrates as food for fishes and crustaceans. I. Devices and methods

Technological problems can be considered as one of the bottlenecks of research concerned with culturing aquatic invertebrates in the laboratory, as well as at the pilot and mass production stages.Oxygenation problems, circulation of the food and sedimentation problems can easily be solved by adapting the shape of the culturing vessels, i.e., by using funnel-shaped bottoms or high, narrow cylinders. In both cases, the food particles, settled on a very small bottom area, can easily be blown back into suspension using an air pump, which re-aerates the medium at the same time.A number of culturing devices for different categories of organisms, including algae are described and commented on. The only power source involved is compressed air which aerates, keeps the water circulating, resuspends particles which have settled to the bottom and even provides CO2 in the case of algal culturing