岩手県越喜来湾における褐藻ヒジキの多回収穫型養殖 Multi-harvestable aquaculture of Sargassum fusiforme (Phaeophyta) in Okirai Bay, Northeast Japan
Both intact thalli of <i>Sargassum fusiforme</i> and those without holdfasts were aquacultured in Okirai Bay, Northeast Japan, to establish them as a multi-harvestable aquaculture resource. Elongated main branches (edible part) of the intact thalli were harvested twice (August 2005 and June 2006) during 1.5 years of aquaculture (November 2004-June 2006). However, two fouling organisms, <i>Laminaria japonica</i> and <i>Mytilus galloprovincialis</i>, also occurred on the aquaculture rope. As a fouling countermeasure, <i>S. fusiforme</i> thalli without holdfasts were aquacultured for 6 months (February-August 2005) with freshwater treatment (biweekly 2-min exposures). Their stipes regenerated holdfasts, and the attached holdfasts elongated around the aquaculture rope; moreover, the new holdfasts gave rise to a number of stipes, which became the bases of new main branches. The elongated main branches were harvested after 4 months of aquaculture. Thalli without holdfasts collected from the rope were aquacultured again for ca. 1 year (October 2005-August 2006) with the same freshwater treatment. After 8 months, elongated main branches were harvested from these thalli with their new regenerated holdfasts. The freshwater treatment was effective to remove <i>L. japonica</i>, but it had no effect on fouling by <i>M. galloprovincialis</i>. Therefore, the two successive harvests were conducted before the mass occurrence of <i>M. galloprovincialis</i> in the summer.
- Sessile organisms
Sessile organisms 25(1), 17-23, 2008-02-29