Improving the Food Quality of Sea Urchins Collected from Barren Grounds by Short-Term Aquaculture under Controlled Temperature

摘要

In west Hokkaido, there are many barren grounds where Mesocentrotus nudus is abundant. These sea urchins have poor commercial value due to their thin gonads, but can become marketable by intensive feeding for gonad enhancement. In general, the quality of sea urchin gonads as food products decreases as gametogenesis progresses. Mature ovaries and testes are not suitable as food products because of the unpleasant taste caused by gamete content and the melting appearance caused by gamete flow via breakage of the gonoduct. Immature to pre-mature gonads that contain predominantly nutritive phagocytes (somatic nutrient storage cells) and not copious gametes have a higher commercial value. Thus, enhancing the nutrient accumulation into nutritive phagocytes plus suppressing gametogenesis is advantageous for sea urchin aquaculture. We are developing short-term aquaculture techniques to improve the food quality of M. nudus collected from barren grounds under controlled temperature to suppress gametogenesis. Rearing M. nudus under a low temperature between summer and autumn has proved to be effective to increase the gonad size without the quality deterioration caused by maturation.