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内海・内湾漁業生物の生産力について
https://fra.repo.nii.ac.jp/records/2003310
https://fra.repo.nii.ac.jp/records/200331012d5da0c-9b0d-4440-ba6c-6704c8afa6f6
| Item type | 紀要論文 / Departmental Bulletin Paper(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2024-04-25 | |||||
| タイトル | ||||||
| タイトル | 内海・内湾漁業生物の生産力について | |||||
| 言語 | ja | |||||
| タイトル | ||||||
| タイトル | Productivity of the Inshore Fishing Grounds Changes of Productivity in the Seto Inland Sea (Review) | |||||
| 言語 | en | |||||
| 言語 | ||||||
| 言語 | jpn | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_6501 | |||||
| 資源タイプ | departmental bulletin paper | |||||
| アクセス権 | ||||||
| アクセス権 | metadata only access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
| その他（別言語等）のタイトル | ||||||
| その他のタイトル | 瀬戸内海漁業資源の生産力 | |||||
| 言語 | ja | |||||
| 著者 |
多々良, 薫
× 多々良, 薫 |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | The Seto Inland Sea is the largest inshore fishing ground - about 19 × 103 km2 - in Japan. Annual production amounts to more than 400 × 103 m.t. in the boat fishery and about 300 × 103 m.t. in the aquaculture, totaling more than 38 m.t./km2/year. In the present paper, the fishery of the Seto Inland Sea is outlined initially. The Seto Inland Sea includes eight fishing grounds which are connected by passages and channels. Although hundreds of islands and strong tidal currents create diverse environmental conditions, water is moderate and clam as a whole with the average depth of 30 meters and the annual range of water temperature is about 10°C to 25°C. Under these conditions, the area is the largest nursery ground along the Japanese Islands. More than 600 species of marine organisms including more than 100 commercial species are reported from this area. Those commercial species can be categorized into three ecological groups: (a) Spawner entering type (Spanish mackerel, Red sea bream, etc.) which enters the Inland Sea in their spawning season from the outer sea area, (b) Younger entering type (Mackerel, Horse mackerel, Kuruma prawn, etc.) which flows into the Inland Sea in their various stages of egg or juveniles and then extend its distribution to the outer sea area, and (c) Proper type (Sea bass, Sand lance, etc.) which stays in the Inland Sea throughout their life history. As described above, the Inland Sea fishery resources consist of a large number of species, but the quantity of each species is very small. Only the catch amount of Anchovy exceeds 10% of the total production, Sand lance and Short necked clam attain 5%, while Red sea bream and Kuruma prawn are less than 0.7%. Reflecting these facts, fisheries business in this area is small and diverse. The small type fisheries were modernized and had become equipped with high powered boats during the period of high economic growth during the 1960s. As a result, fishing efforts intensified sharply, and total production increased by 1.7 times in that single decade. The increased demand for species with higher commercial values was particulary notable and this eventually caused depletion of the resources. The 1960s also saw a tremendous growth in the aquaculture industry; including of breeding of Yellowtail, Red sea bream and Kuruma prawn, and oyster and seaweed cultures. The improvements in technology allowed a larger scale cultivation possible and increased the productivity. The present day aquaculture faces a dorp in the market demand for its products which seems to restrain the growth of the industry. Water pollution and coastal reformation caused serious environmental problems in the 1960s. Industrialization and urbanization of the coastal land area induced the eutrophication. Thus, the primary production of the inshore water increased considerably. The appearance of red tide in various parts of fishing grounds then caused numerous problems to the fishing industry. Productivity of the fishing grounds was very high as mentioned above, however, the productivity differed from one fishing ground to another. The inshore fishing ground with strong eutrophication seem to attain higher productivity. The relation between the water depth of fishing ground and the productivity showed clear relevance as shown in Figs. 7 & 8. In order to study these relations, the degree of inshoreness for each fishing ground was calculated by the following equation. E = k/D.T where E = degree of inshoreness D = mean water depth of fishing ground in meter T = transparency in meter k = constant The relations between the productivity and E were plotted, and the two curves showing changes in productivity per km2 (Fig. 10) and another curve per km3 (Fig. 11) were drawn. These curves indicated that the productivities and the degrees of inshoreness are related. It had been conjectured previously that the primary production of the sea increased by the eutrophication. The amount of primary production utilized through fishery during the period from 1951 to 1977 was estimated by the method presented in the separate paper: "Relation between the Primary Production and the Commercial Fishery Production in the Fishing Ground". Using the figures derived from the above method, the historical changes of the relation between the amount of estimated consumption of primary production and the actual catch amount was then discussed. Generally the relation seems to be a linear one (Fig. 12), excluding last three years (1975 - 1977).The total catch amount increased by 2.6 times during twenty five years since 1951, and the estimated consumption of primary production increased by 1.6 times in the same period. Figure 13 shows that the mean trophic level of the catch decreased accompanying the quantitative leveling up of the catch. The fish of the higher trophic level has, most case. higher commercial value. Then degrading of the trophic levels of the fish caught results a significant impact in the commercial fishery. In the Seto Inland Sea, the catch amount could be increased up to the level of 600 × 103 m.t. However, at the same time, the mean trophic level should be lowered about 0.25. Therefore, it can be summerized that the utilization of primary production in the sea area is characterized by the fishery and the features of the fishery resources which are continually transformed by the change of fishery. The recent three years of unprecedented growth in catch amount were derived from the effective catchings of the outbursted shellfishes and squids in the eutrophicated fishing grounds. The exploitation of these multiplying species became very important in recent years as a surplus catch. To make this surplus harvest a promising one, there should be a systematic coorporation between the scientific monitoring of resources and the management of commercial fisheries. | |||||
| 言語 | en | |||||
| bibliographic_information |
ja : 南西海区水産研究所研究報告 en : Bulletin of the Nansei Regional Fisheries Research Laboratory 巻 13, p. 135-167, ページ数 33, 発行日 1981-03 |
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| 出版者 | ||||||
| 出版者 | 南西海区水産研究所 | |||||
| 言語 | ja | |||||
| 出版者 | ||||||
| 出版者 | Nansei Regional Fisheries Research Laboratory | |||||
| 言語 | en | |||||
| item_10002_source_id_9 | ||||||
| 収録物識別子タイプ | PISSN | |||||
| 収録物識別子 | 0388-841X | |||||
| item_10002_source_id_11 | ||||||
| 収録物識別子タイプ | NCID | |||||
| 収録物識別子 | AN00181988 | |||||
| 情報源 | ||||||
| 識別子タイプ | Local | |||||
| 関連識別子 | nnf_k_13_135 | |||||
| 関連サイト | ||||||
| 識別子タイプ | URI | |||||
| 関連識別子 | https://agriknowledge.affrc.go.jp/RN/2010232927 | |||||
| 言語 | ja | |||||
| 関連名称 | 日本農学文献記事索引(agriknowledge) | |||||
