Potential for Freezing and Freeze-Drying as Methods for Preserving Microalgal Concentrates in Bivalve Hatcheries

摘要

As the human population grows, there is a growing demand for bivalves as they are low in saturated fats and a nutritious source of omega-3 fatty acids. There is also increasing reli-ance on bivalve aquaculture, which has increased in Canada and aroundthe world over the past two decades, to provide these healthy products for human consumption. The limitation in this industry is that it may not be able to increase its production enough to meet growing demands unless hatcheries are able to supplyjuveniles to marine grow out farms. Hatchery rearing of bivalves depends on the production of live microalgae which is costly and unpredictable. Hatchery production would be improved if optimal microalgal diets could be concentrated and preserved in frozen orfreeze-dried forms. An effective concentrated diet would improve reliability and success of bivalve aquaculture by accelerating growth rate of young bivalves under repeatable and controlled conditions while maximizing return on microalgae-culture investment. In the Maritimes, this microalgal supply problem is particularly evident in aquaculture of the American oyster, Crassostrea virginica. A cost-effective frozen or freeze-dried alternative to onsite microalgae would reduce operating costs in hatcheries and improve the efficiency of juvenile oyster production. This paper reviews the literature on the use of concentrated microalgae as food for juvenile bivalves.