Practical research on rearing broodstock abalone using a closed recirculating system

Abstract

Hatcheries in Japan's Tohoku region induce the gonadal maturation of Haliotis discus hannai by controlling the water temperature. However, the cost of heating the water places financial pressure on the hatcheries. This study showed that the heating cost in rearing abalone broodstock can be reduced using a simple closed recirculating system that was constructed using common commercial products. During our experiment, the water quality parameters including ammonia-, nitrite- and nitrate- nitrogen were kept under recommended safety levels, pH did not show a significant decrease during the breeding period. Although the calcium ion concentration and salinity value were less stable in the closed recirculating system than in the flow-through system, both were within adequate levels for rearing abalone over long periods. Moreover, the gonadal maturation of 11, discus hannai was not inhibited by rearing in a closed recirculation system. And the electric power consumption in the closed recirculating system was reduced to about one seventh of that in the flow-through system.