East China Sea

Japanese: 東シナ海 - ひがししなかい（英語表記）East China Sea

A marginal sea of the Pacific Ocean east of China. In China, it is called the East Sea. It is bounded in the north by a line connecting the mouth of the Yangtze River (Changjiang) and the southwest corner of Jeju Island, in the south by a line connecting Nan'ao Island in Guangdong Province and Eluanbi in Taiwan, in the east by an island arc stretching from Kyushu through Okinawa to Taiwan, and in the west by mainland China. Its area is 1,249,000 square kilometers. The area northwest of the line connecting Taiwan and the Goto Islands of Japan is basically part of the continental shelf, accounting for two-thirds of the total area. The area southeast of this line is the continental slope. The average depth is 188 meters, and the maximum depth is 2,719 meters. In waters less than 100 meters deep, the seabed is mostly flat and composed of sand and mud, making it suitable for bottom trawl fishing. The seabed between 30 degrees north latitude and 32 degrees north, and between 124 degrees east longitude and 126 degrees east is sandy and muddy, making it a place where many kinds of fish spend the winter. The length of the coastline of mainland China is 4,200 kilometers, with many inlets and inlets, good harbors, and the area with the most islands of China's five major ocean regions. Taiwan Island and about 60% of China's coastal islands are distributed here. The areas around these islands provide good fishing grounds, and the waters around the Zhoushan Archipelago in particular are said to be a treasure trove of marine fish. It is the largest producer of hairtail, big yellow fish, yellow croaker, and squid, which are considered to be representative marine economic fish in China, and it also has a large crab catch. In addition, there are good fishing grounds off the coast of Japan from the Goto Islands to Okinawa, and deep-sea fishing operations are being carried out based on the Japan-China Fisheries Agreement. In addition, the continental shelf in the southern part of the ocean is predicted to be rich in oil resources, and drilling of offshore oil fields has begun in areas such as east of Shanghai.

[Kono Michihiro]

Sea conditions

Sea surface temperatures are fairly uniform at 25 to 28°C in summer, but in winter they are over 20°C north of the Nansei Islands, where the Kuroshio Current flows, and below 10°C in the north. Sea surface salinity is over 34.0 psu (psu stands for practical salinity unit) in the southeast, but is 31 to 32 psu from the central and northern parts, and especially at the mouth of the Yangtze River, salinity falls to below 20 psu during the rainy season.

The main ocean currents are the Kuroshio Current (current speed: about 2 knots), which flows in between Taiwan and Ishigaki Island, passes through the north of the Nansei Islands, and then exits the Tokara Strait; the branch of this current flows north along the west of Kyushu, eventually reaching the Tsushima Warm Current; and the coastal current flows south along the Chinese mainland. However, regarding the origin of the Tsushima Warm Current, apart from the view that it is a branch of the Kuroshio Current that flows north along the west of Kyushu, there is also the view that there is a series of ocean currents that run from the Taiwan Strait to the Tsushima Strait that are separate from the Kuroshio Current. In addition to the ocean currents, there are also tidal currents that are prominent in shallow waters, reaching 1-2 knots in the central area and 2-3 knots along the coast. Furthermore, the tidal range is large in the Taiwan Strait, reaching more than 7 meters in some places, and at spring tides, the "bore phenomenon" can be seen at the mouth of the Qiantang River in Hangzhou Bay, where tidal waves surge like a tsunami.

[Kouichi Nagasaka and Koichi Ishikawa]

"Fish of the East China Sea and Yellow Sea," edited by Okamura Osamu and edited by Yamada Baifuji et al. (1986, Fisheries Agency, Western Sea Regional Fisheries Research Institute)" ▽ "Folklore of the East China Sea Cultural Zone, by Shimono Toshimi (1989, Miraisha)" ▽ "Sea and Archipelago Culture 4: East China Sea and Western Sea Culture," edited by Amino Yoshihiko, Obayashi Taryo, Tanigawa Kenichi, Miyata Noboru and Mori Koichi (1992, Shogakukan)" ▽ "East China Sea and Northwest Kyushu," edited by Amino Yoshihiko et al. (2000, Japan Library Center)" ▽ "Bio-ecological Characteristics of Major Resources in the East China Sea and Yellow Sea: A Comparison of Knowledge between Japan and China," edited by Horikawa Hiroshi et al. (2001, Fisheries Agency, Western Sea Regional Fisheries Research Institute)"

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

中国の東方にある太平洋の縁海。中国では東海とよぶ。北は長江(ちょうこう／チャンチヤン)（揚子江(ようすこう／ヤンツーチヤン)）の河口と済州島(さいしゅうとう／チェジュド)南西角を結ぶ線、南は広東(カントン)省の南澳島(なんおうとう／ナンアオタオ)と台湾の鵞鑾鼻(がらんび／オーロワンピー)を結ぶ線、東は九州から沖縄を経て台湾に至る島弧、西は中国本土に囲まれた水域である。面積124万9000平方キロメートル。台湾と日本の五島(ごとう)列島を結んだ線より北西は基本的には大陸棚に属し、総面積の3分の2を占める。この線より南東は大陸斜面である。平均深度188メートル、最大深度2719メートル。深度100メートル以浅の水域は海底の大部分が平坦(へいたん)で砂泥質からなり、底引網漁業に適している。北緯30度以北32度まで、東経124度以東126度までの間の海底は砂混じりの泥質で、多種類の魚の越冬する場所である。中国大陸の海岸線の長さは4200キロメートルに達し、海岸線の出入りが多く良港に富み、また中国五大海区のうちではもっとも島が多い。台湾島および中国の沿海島嶼(とうしょ)の約60％がここに分布する。これらの島々の周辺は良好な漁場をなし、ことに舟山群島(しゅうざんぐんとう／チョウシャンチュンタオ)周辺の海域は海産魚類の宝庫といわれる。中国の代表的海洋経済魚とされるタチウオ、フウセイ（大黄魚）、キグチ（小黄魚）、イカの最大の産地で、カニの漁獲量も多い。また日本沿岸も五島列島から沖縄にかけて好漁場がみられ、日中漁業協定に基づく遠洋操業が実施されている。また本海南部の大陸棚の部分には石油資源の埋蔵が豊富と予測され、上海(シャンハイ)東方などで海底油田の掘削が始まっている。

［河野通博］

海況

海面水温は、夏季には25～28℃とほぼ一様であるが、冬季には黒潮が流れている南西諸島北側の20℃以上に対して、北部では10℃以下となる。また海面の塩分は、南東部では34.0psu（psuはpractical salinity unitの略、実用塩分単位）以上であるが、中部以北では31～32psu、とりわけ長江河口では雨期には塩分は20psu以下となる。

　おもな海流は、台湾と石垣島の間から流入し南西諸島北側を経て吐噶喇(とから)海峡に抜ける黒潮（流速2ノット前後）およびこの分流で九州西を北上し、やがては対馬(つしま)暖流に至るものと、中国大陸側を南下する沿岸流とがある。ただし、対馬暖流の起源については、九州西を北上する黒潮の分流であるとする見解とは別に、台湾海峡から対馬海峡に続く一連の、黒潮とは別の海流系があるという考えがある。また海流に加えて浅海部では潮流も卓越しており、中央部で1～2ノット、沿岸部では2～3ノットに達している。さらに台湾海峡では潮差も大きく、一部では7メートル以上にも及び、大潮時には杭州(こうしゅう／ハンチョウ)湾銭塘江(せんとうこう／チエンタンチヤン)河口では潮汐(ちょうせき)波が津波のように押し寄せる「ボア現象」がみられる。

［長坂昂一・石川孝一］

『岡村収監修、山田梅芳ほか編『東シナ海・黄海のさかな』（1986・水産庁西海区水産研究所）』▽『下野敏見著『東シナ海文化圏の民俗――地域研究から比較民俗学へ』（1989・未来社）』▽『網野善彦・大林太良・谷川健一・宮田登・森浩一編『海と列島文化4　東シナ海と西海文化』（1992・小学館）』▽『網野善彦ほか監修『東シナ海と西北九州』（2000・日本図書センター）』▽『堀川博史ほか編『東シナ海・黄海主要資源の生物・生態特性――日中間の知見の比較』（2001・水産庁西海区水産研究所）』