In mollusc hatcheries and nurseries, live microalgae are traditionally used as feed for bivalves. Despite recent improvements in efficiency, such intensive culture of microalgae represents major cost factors in the production of bivalve larvae and spat. In an attempt to provide cost-effective alternatives and to simplify hatchery-nursery procedures, non-living algal food has been developed over the past few years. Substitution products such as bacteria, yeast, vitamin or docosahexaenoic acid enriched powders, dry and concentrated microalgae and microcapsules have been tested and evaluated on an experimental scale. The present article reviews major research aimed at developing non living diets in mariculture, which generally resulted in lower growth and higher mortalities than that recorded for controls fed live microalgae. At the present time, concentrated and dried microalgae appear to be the best alternative products for bivalves, for juveniles essentially, while microcapsules provide an excellent research tool to study their nutritional requirements.

This paper presents a summary of information on reproduction biology in the scallop, Pecten maximus, which is required for the successful reseeding and intensive aquaculture programs developed in France since 1982. Data are presented on the following subjects: environmental factors that sustain gametogenic activity and the time of year this activity occurs; biochemical changes that are associated with gametogenesis; the consistency of egg quality; and development of a simple test to predict egg quality.