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

In west Hokkaido, there are many barren grounds where Mesocentrotus nudus isabundant. These sea urchins have poor commercial value due to their thin gonads, but can becomemarketable by intensive feeding for gonad enhancement. In general, the quality of sea urchingonads as food products decreases as gametogenesis progresses.Mature ovaries and testes arenot suitable as food products because of the unpleasant taste caused by gamete content and themelting appearance caused by gamete flow via breakage of the gonoduct. Immature to pre-maturegonads that contain predominantly nutritive phagocytes (somaticnutrient storage cells) and notcopious gametes have a higher commercial value. Thus, enhancingthe nutrient accumulation intonutritive phagocytes plus suppressing gametogenesis is advantageous for sea urchin aquaculture.We are developing short-term aquaculture techniques to improvethe food quality of M. nuduscollected from barren grounds under controlled temperature to suppress gametogenesis. RearingM. nudus under a low temperature between summer and autumn hasproved to be effective toincrease the gonad size without the quality deterioration caused by maturation.