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笠岡湾の生産力に関する研究
https://fra.repo.nii.ac.jp/records/2005112
https://fra.repo.nii.ac.jp/records/20051126aff5917-70c8-46dc-bc9d-91ea363407a6
| Item type | 紀要論文 / Departmental Bulletin Paper(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2024-05-17 | |||||
| タイトル | ||||||
| タイトル | 笠岡湾の生産力に関する研究 | |||||
| 言語 | ja | |||||
| タイトル | ||||||
| タイトル | STUDY ON PRODUCTIVITY OF KASAOKA BAY | |||||
| 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 | |||||
| 著者 |
井上, 明
× 井上, 明 |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | The science of limnology has been directed and advanced to the study of biological productivity of water, its nature and function, since the researches conducted by Thieneman, Naumann and others in recent years. For the investigations on the same direction in limnological science of Japan, hydrobiologists such as Hogetsu (1948-1952), Nakano (1950-1953), Hanaoka(1947-1955) and others may be named active workers, and these workers are believed to be responsible to initiate the studies on aquatic organisms from static biology to biotic productivity of water. Studies of this nature in seawater may be characterized and hampered in their conduct by those facts as listed here as compared to those in freshwater. 1. Existence of significant water currents. 2. Moving and migration of organisms in larger extent. 3. Habitats are stabilized, and organisms show more restricted adaptation to varied environments. The productivity of aquatic environment may be shown by the amount of valuable organisms produced from an unit of water in a given time of period. The productivity may be determined by interrelation of organism and environment as well as biological association. A routine procedure taken in the calculation of the productivity has been the quantitative analysis of a partial phenomenon taking place in the cycle of materials, and efforts were made in recent years to measure photosynthesis of chlorophyll. Yoshimura (1932), based on the data presented by Birge, Juday and others, reported the correlation of water transparency to suspended matters. Hanaoka (1952), in a belief that the measurement of a part of productivity of water including primary productivity can hardly indicate the fishery productivity, evaluated adoption of an indicator, of which the amount of suspended matters proved to show an intimate correlation to fish production. While, Aikawa (1936) showed the amount of benthic organisms indicating a relation to fish catch. The present writer, in the study of Kasaoka Bay, an inlet water in Seto inland-sea, examined critically the relation between fish catch and suspended matters in water and benthos. In the same study the technique involved in the collection of bottom organisms was tested. Also, study was made on environmental factors affecting the fluctuation in extended years of fish catch by "masuami" set-net, Suspended matters and fish catch 1. The total fish catch in Kasaoka Bay amounted 56,000kan(1kan=3.75kg) in 1953, while, a presumed amount of catch calculated following Hanaoka's (1952) formula derived 58,000 kan. The two figures are approximate, however, it must be noted that the transparency of the water in inner bay is affected by the depth and current of water, and influenced by inflow from land. 2. In the study of relation between the piscivorous fish and salinity of water in Kasaoka Bay, it was found that these fish constitute 2.38% of total fish species in the bay. The chlorinity of surface water for a year, 16.5‰ indicated, according to a conversion formula proposed by Hanaoka (1953), the presence of piscivorous fish population amounting 2.41%. Thus, the proposed percent of fish-eating fish is closely approximate to the actual percentage. The piscivorous fish dwelling Kasaoka Bay which is a typical inner bay were represented mainly by individuals of young ages, and the food items taken by them showed their feeding adhered to benthic animals. "Masuami" set-net The fishing gear "masuami" is commonly seen operated in neighbouring waters of Kasaoka Bay. Since, in the operation of this particular set-net, the gear of same size are adopted in a given locality for extended years, the catch derived presents a source information concerning the fluctuation of migratory fish shoals. 1. Among 500 sets examined in the present study, those adopted in coastal waters are usually smaller than those used in island waters. 2. The fishing season lasts longer on the coast than in islands. The months of larger catch vary by the fishery cooperatives, but it is usual to see the fishing condition in general shifting from outer to inner waters in the bay. 3. The set-net catches more than 73 species of fish, and coastal waters find major forma such as mullet, black sea-bream (Mylso), sea-bass (Lateolabrax), shrimps, cuttle-fish and crabs, while, red sea-bream (Chrysophrys) is the representative species caught in island water. The constitution of the species was found to vary by regions generally accompanied by the change in salinity of water. 4. The fishing and environmental factors were analysed to find their relationship. Some of the findings are : (1) The oceanographical data collected at Kasaoka Branch and Onomichi Branch, Inland Sea Regional Fisheries Research Laboratory revealed that the water in Kasaoka Bay received a hcavier effect of inland water than in the water of Onomichi channel. The weather condition was checked on the data collected by Matsunaga Weather Station, Ministry of Communication. In the examination of yearly fluctuation of oceanographical and weather conditions from 1950 to 1957, the low salinity of water in 1954 was noted, and it was believed that the low salinity was derived due to factors other than weather condition. (2) The yearly fluctuation of the fishing was studied on the amount of catch per unit of effort for each fishery cooperative. The catch gained in the years 1960 to 1955 was not much varied, but it dropped markedly in 1956-1957. As to the migratory routes of fish into Kasaoka Bay which were analysed on the record of Konoshima Uchiura Fishery Cooperative, 1946-1965, it was understood that the fish staying in offshore waters up to July in a year migrate to shalower and inner waters in the months to follow. (3) The fishing experiences the peak in April and May in island waters, and September in inner part of the bay. In the year when the specific gravity of water is high in July the fish catch is favourable in the same month. The reverse was also held true. (4) The maximum and minimum catch by one set of the net per day were analysed for 1960-1965 period correlated with environmental factors. The catches, varied by species of fish in certain extent, were affected by oceanography and weather. The maximum catch was experienced on fewer precipitation (days and amount), and on the day previous to strong or southernly wind. The large catches were also met on the day or one day ahead of longer day light hour. The continuous rainfall and higher precipitation resulted the minimum catch, which is often accompanied by strong wind also. The minimum catch was also seen on the day of strong wind especially of north-east direction, or, the day or one day ahead of shorter day light hour. Benthic organisms The benthic animals afford valuable food materials to fishes in the bay, and the abundance of these organisms was believed to affect directly the amount of fish production. 1. The Ekman-Birge sampler, tested in the present study, was found not highly dependable in the quantitative analysis of benthos. The efficiency collecting bottom samples of the tool was noted to vary by weather, water and bottom materials. 2. A qualitative analysis of the benthos was made from July 1952 to December 1953 on the materials collected by the Ekman-Birge sampler. Some of the results are ; (1) The counting made on the number of benthic animals found bivalves and annelids as major forms, each amounting 35% or so in community : the former showed the highest popuIation in April and the latter September. The total population of benthic animals was assumed to amount 1.55 × 10¹⁰ in a year within Kasaoka Bay with total area of about 41.4 km². The benthos community of Kasaoka Bay was classified into 3 regional types after the method of Motomura (1951). finding each region characterized by respective value of salinity. A similar regional type of benthos community was also observed in Mutsu Bay (Yamamoto, 1951). (2) The weight of benthic animals showed that bivalves and echinoderms were representative forms in the bay, and the total weight of bottom animals produced in a year was estimated to amount 3,600 ton. (3) The distribution of the benthos was clarified by species. 3. The benthic animals were studied referred to environmental conditions. Some of the results are : [1] The population density of the animals was found to be thinner when the consumed potassium permanganate was measured especially high or low. The number of molluscs was counted fewer where CPP reading was low, and a reverse relation was noted for polychaete worms. However, the same chemical character did not give influence on the population of other animals so significantly, [2] The close correlation of consumed potassium permanganate to decrease by incalescence was expressed by a formula, Mn = - 2.782 + 2.927 Ig where Mn is mg in gr of dried material, and Ig decrease by incalescence in%. [3] The values of CPP were found to vary parallel to the depth of water. | |||||
| 言語 | en | |||||
| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | 笠岡湾について,魚類の生産力標示方式に関する検討を行ない,ます網によって漁獲された魚類の漁況および底棲生物と環境要因などについて調査した。1. 懸物質量または透明度と漁獲量との関係は,花岡(1952)と一致するが,透明度は水深,流速,陸水などによって強く影響をうける。2. 食物連鎖区分による魚食性魚類の割合は,湾口の巾,平均水深,塩分濃度によって規定されるというが,笠岡湾のような強内湾性の内湾においては,魚食性魚類に属する魚類の大半は若年魚で,これらは,食性からみて底棲生物捕食魚類とみなすことが妥当である。3. ます網漁業について,単位努力当たり漁獲量の永年変動をみると,魚種ごとに増減の傾向を異にするが,全般的に昭和31,32年の漁獲量の減少が目立つ。漁の豊凶の要因は複雑であって,容易に判断できないが,海況,気象の環境異変による現象とは認められない。4. 魚類が湾内へ回游する経路は,沖合水の進入経路をたどると推定されるが,春から夏には沖合に,秋から冬には沿岸近く回游する。5. 高鹹水域は,低鹹水域に比較すると,魚種組成は単純で大型魚類が多く,卓越種の季節的変化が小さい。6. 日日の豊凶の要因は,魚種によって多少異なるが,一般的に気象,海況によっておこる。漁獲量が極大を示すばあいは,降雨日数,降雨量ともに小さく,風程は極大の日の前日に大きく,風向は南西寄りであり,日照時数は極大の日とその前日に大きい。これに反して,極小のばあいには,降雨日数,降雨量ともに大きく,風程は極小の日に大きく,風向は北東寄りで,日照時数は極小の日とその前日に小さい。7. 底棲生物によって生産量を推定するばあいには,まず採集方法の改善がのぞまれる。すなわちエクマンパージを使用して底棲生物を採集するばあい,採集操作が気象,海況によって一定せず,また泥質によっても採泥量が不均一で,特に魚類の主要な餌料であるェビ類,ガンマルス類が,ほとんど採集できない。8. 底棲生物と環境について検討した。すなわち過マンガン酸カリ消費量は,水深,灼熱減量と密接な相関を示し,多毛類は過マンガン酸カり消費量の少ない場所に多く,軟体類は過マンガン酸カリ消費量の多い場所に多い傾向を示す。 | |||||
| 言語 | ja | |||||
| bibliographic_information |
ja : 内海区水産研究所研究報告 en : Bulletin of Naikai Regional Fisheries Research Laboratory 巻 20, p. 1-115, ページ数 115, 発行日 1963-01 |
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| 出版者 | ||||||
| 出版者 | 内海区水産研究所 | |||||
| 言語 | ja | |||||
| 出版者 | ||||||
| 出版者 | Naikai 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 | 0497-5022 | |||||
| item_10002_source_id_11 | ||||||
| 収録物識別子タイプ | NCID | |||||
| 収録物識別子 | AN00176718 | |||||
| 情報源 | ||||||
| 識別子タイプ | Local | |||||
| 関連識別子 | nai_k_2001 | |||||
| 関連サイト | ||||||
| 識別子タイプ | URI | |||||
| 関連識別子 | https://agriknowledge.affrc.go.jp/RN/2010841499 | |||||
| 言語 | ja | |||||
| 関連名称 | 日本農学文献記事索引(agriknowledge) | |||||
