長崎県新三重地区における磯焼け対策について(平成21年度日本水産工学会秋季シンポジウム「持続的な磯焼け対策の実践に向けて」)

概要

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Along the rocky shores in Shi-Mie, Nagasaki Prefecture, seaweed beds have decreased since 1990's and urchin barrens are extensively common. To recover seaweed beds, we removed sea urchins and supplied 'seeds' of seaweed in an area of 7,000m^2 in 2008. The total number of sea urchin removed in one year is 25,700 (Anthocidaris crassispina 19,700 and Diadema spp. 6,000) Six hundreds thallii of Sargassum were deployed with modified spore bags on the bottom from spring to summer. Drifting seaweeds were abundantly captured by modified surface gill nets and supplied 'seeds' for the urchin-removed area. In December 2008, the density of juvenile Sargassum (5〜10mm in length) was higher in the urchin-removed area (422.4ind./m^2) than that in the control area (136.0ind./m^2). In May 2009, Sargassum beds were established in the urchin-removed area while the control area continued to be a barren ground.
2011-07-15