Seaweed beds have recently declined and changed into barren ground in some Japanese coastal areas. On the other hand, the seaweed beds are important for production of fishery resources and conservation of marine environment. Experimental study to form a seaweed bed by preventing invading herbivores was arranged at the western part of Wakasa Bay, Sea of Japan. By using a net over the artificial constructions where Sargassum patens had not previously grown, young S. patens were able to survive. The effect of the covering net on the substrate crevasses where some herbivores may inhabit. To form a submarine forest effectively in this area. it was suggested that it is necessary to prevent herbivores from hiding in the substrate crevasses as habitats.

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アマモの草体の引き抜きに抗する固着力に及ぼすアンカー材の効果を定量的に把握するため,市販の粗礫および粗粉砕カキ殻を基質(砂または泥)との容積比率10%,50%および100%に配合し,広島県三津口湾で採取したアマモを,屋外20tコンクリート製水槽底に設置し,栽培開始3ヶ月後および1年6ヶ月後に引き抜き実験を行った。アマモの草体に引き抜きに抗する固着力については,粗礫またはカキ殻20%程度の混入率で最大となり,一方,粗礫100%およびカキ殻100%の場合に最も低下することが確認された。アマモ生育基盤を造成する際に使用する底質素材の配合・調整について定量的に検討する上での数値データが把握されたことから,アマモの生育基盤に限らず,いわゆる人口海岸の地先での浅場造成における設計の高度化にも資することが示唆された。

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In the coastal areas of the Seto Inland Sea of Hyogo prefecture, seaweed beds have been declined in their density because of reclaiming due to drastic urbanization and industrialization after the high economic growth period in the 1950's in Japan. In order to estimate the area of seaweed beds in the 1950's, the following methods were adopted. Questionnaire survey was carried out in 23 fisheries departments and 72 fisheries cooperatives and then set the objected area from this result, and the range of present seaweed bed areas was obtained by using the topographical maps, charts, side scanning sonar, underwater video camera and transparency. As the results of our survey, total seaweed bed area in the 1950's was about 2300ha but about 920ha was disappeared by the reclaiming (430ha), bank protection work (140ha) and others (280ha). Good grasp for the transition of seaweed bed area in the past is very important issue to carried out the natural reproduction plan of seaweed bed area in future.

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ミズクラゲに超小型データロガーを装着して鉛直移動を記録した。データロガーは水槽内では5時間以上装着可能で,装着前後の傘の拍動数に有意差はなかった。大村湾浅海域においてこの方法で,2009年6〜7月と10〜11月に10個体について記録を得た。ミズクラゲは6〜7月の日中には表層付近に,10〜11月には時間帯にかかわらず海底付近に滞在することが多かった。10個体中8個体がデータロガーを装着して放流した際に沈降した。この沈降行動は取り付け作業に対する反応かもしれない。

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Fishery in Fukui Prefecture, the decline in catches and production value, increased operating costs, an aging workforce and the decline of fisheries, producer prices drop, reducing the consumption of seafood has become the issues. The county has developed the following five basic measures to resolve the issues. 1. Promote increased consumption of marine products to provide of local seafood and fresh produce to consumers, 2. Promote the activation of fishing utilizing local resources to increase the number of tourists, 3. Promote context-sensitive resource management for stable catches, 4. Promote a shift to lowcost, high profitable fisheries in order to improve and increase the income of fishermen, 5. Advance the development of core fishers to revitalize the fishing village

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Various environmental changes including the increase of large-sized jellyfish and the expansion of muddy area have recently been occurring in Wakasa Bay and simultaneously fish catches and production values have been reducing. Towards these environmental changes, various technologies have been developed to maintain and restore the fishing ground environment Applying the respective technology in simple manner is not sufficient for effective expansion of these techniques but it is necessary to fully consider the restoration goals and methods from the perspectives of fishery production, proper nutrient concentrations, securing shallow bottom (tidal flats and seaweed beds) and the amount of bottom dissolved oxygen. This paper illustrates the cases of ocean fertilization technologies for the purpose of increasing the fishery production, biological habitat improvement technologies, and improvement technologies to improve the bottom mud quality. These were cited from ones have been so far studied and conducted regarding restoration technology of the fishery environment Furthermore examples of creating mechanisms to promote restoration of the fishing ground environment at regional scale were introduced and the possibilities and problems in the case of applying them to Wakasa Bay were summarized.

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It is very important to understand environment factors of the fishing grounds. In this paper, the author presents the factors of Wakasa Bay in recent years. 1. The surface sea water temperature around Japan is showing a tendency to rise, and a phenomenon was similar in Wakasa Bay. 2. The relationships between the surface sea water temperature in Wakasa Bay and the catching fluctuations of two-year-old and over yellowtail were investigated. As a result, a correlation of both items was suggested. 3. Since 1999, the catch of scomberomorus inhabit in warm waters is increasing rapidly in Japan Sea, and the fish is becoming the important species in Fukui Prefecture. 4. After 2002, a large amount of appearance of giant jellyfish was often observed in Japan sea. It was suggested that a current in Wakasa Bay effected a large accumulation and the long term remaining period of the species.

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In order to protect the snow crab population, a crab sanctuary was established. An untethered remotely operated vehicle was used to gauge crab population numbers in the protected area and an unprotected area between the years 1996-1999. UROV results conclude higher crab densities in the protected area each.

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