Raking: an innovative and sustainable echinoculture method to produce “caviar” without sacrificing sea urchins

Abstract

Sea urchin aquaculture represents a promising tool to achieve sustainable aquaculture, promote sector diversification and obtain high-priced products using low-trophic species. However, although echinoculture has been practised for several decades, this sector has not yet achieved economic sustainability and large-scale development mainly due to problems linked to long-term sea urchin rearing cycles. In this paper we present a groundbreaking production method, called "Raking", for sea urchin caviar production that represents a technological advancement both in terms of production approach and in the final product. Raking, in fact, is a no-kill method for the harvesting of eggs as a final product (sea urchin caviar) from only-female batches of sea urchins, meaning that the same sea urchins are employed through several production cycles. This method, therefore, helps overcome important biological and economic constraints of echinoculture, such as high mortality in the early development stages and the slow speed of growth to reach viable market size. This new production method was compared with a traditional gonad enhancement method known as Bulking. Our results showed that multi-cycle production using the Raking method proved more profitable and sustainable than the Bulking method, and in fact allowed us to obtain a cyclic ovulation with a total regenerative capacity of the ovary of about 3/4 months, employing the same sea urchin batch in each productive cycle. In addition, the sea urchin caviar harvested in this way was appreciated by assessors in terms of its sensory qualities and was actually preferred to the traditional gonad products, when assessors were informed of the sustainability and ethical criteria of the Raking production method.