or Kojima is an uninhabited volcanic island in the
Sea of Japan
The Sea of Japan is the marginal sea between the Japanese archipelago, Sakhalin, the Korean Peninsula, and the mainland of the Russian Far East. The Japanese archipelago separates the sea from the Pacific Ocean. Like the Mediterranean Sea, it h ...
, southwest of the mainland portion of the town of Matsumae and is the southernmost point in Hokkaidō. It is under the administration of the district of Matsumae in
Oshima Subprefecture
is a Subprefectures of Hokkaido, subprefecture of Hokkaido, Hokkaido Prefecture, Japan. As of 2004 it had a population of 456,621 and an area of 3,715.38 km2.
Hakodate Airport is located in the City of Hakodate, Hokkaido, Hakodate.
Ge ...
in
Hokkaido
is Japan's second largest island and comprises the largest and northernmost prefecture, making up its own region. The Tsugaru Strait separates Hokkaidō from Honshu; the two islands are connected by the undersea railway Seikan Tunnel.
The la ...
,
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
. To distinguish Ko Island from other islands with the same name, it is sometimes known as or .
Ko Island is the world's smallest
volcanic island
Geologically, a high island or volcanic island is an island of volcanic origin. The term can be used to distinguish such islands from low islands, which are formed from sedimentation or the uplifting of coral reefs (which have often formed ...
andesitic
Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...
stratovolcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and per ...
. The peak consists of non-alkali
mafic
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...
rocks, dating from the
Early Pleistocene
The Early Pleistocene is an unofficial sub-epoch in the international geologic timescale in chronostratigraphy, being the earliest division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently estimated to span the time ...
overtop of non-alkali
felsic
In geology, felsic is a modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz.Marshak, Stephen, 2009, ''Essentials of Geology,'' W. W. Norton & Company, 3rd ed. It is contrasted with mafic rocks, whi ...
rocks from the
Late Miocene
The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...
-
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58
Several smaller islets surround Ko Island, including Daihiyakushima, Shohiyakushima, Tenjinshima, and Sazaeshima.
To provide refuge for fishing vessels, a small harbor has been put in place.
Flora and fauna
Ko Island has been designated a natural monument. It is a breeding ground for
common guillemot
The common murre or common guillemot (''Uria aalge'') is a large auk. It has a circumpolar distribution, occurring in low-Arctic and boreal waters in the North Atlantic and North Pacific. It spends most of its time at sea, only coming to land to ...
,
Japanese cormorant
The Japanese cormorant (''Phalacrocorax capillatus''), also known as Temminck's cormorant, is a cormorant native to the east Palearctic. It lives from Taiwan, north through Korea and Japan, to the Russian Far East.
The Japanese cormorant has a b ...
, and black-tailed gull. The island, along with some neighbouring islets, have been recognised as an
Important Bird Area
An Important Bird and Biodiversity Area (IBA) is an area identified using an internationally agreed set of criteria as being globally important for the conservation of bird populations.
IBA was developed and sites are identified by BirdLife Int ...
(IBA) by
BirdLife International
BirdLife International is a global partnership of non-governmental organizations that strives to conserve birds and their habitats. BirdLife International's priorities include preventing extinction of bird species, identifying and safeguarding ...
because they also support
colonies
In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the '' metropolitan state'' ...
of rhinoceros auklets.
to the west of Ko Island is the Ko Island Bank, where migratory fish tend to gather. In the adjacent seas there is also
tuna
A tuna is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna (max length: ...
and
squid
True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...
. In previous times it was referred to as the . For this reason it is a major fishing area for fishermen out of Matsumae, especially because of the decline in the
Arabesque greenling
The Okhotsk atka mackerel (''Pleurogrammus azonus''), also known as the Arabesque greenling, is a mackerel-like species in the family Hexagrammidae. It is commonly known as hokke in Japan and imyeonsu in Korean. The primary population of the fi ...
over the last 24 to 25 years.
The predominant vegetation on the island is grasses, but there are stands of
Acer pictum subsp. mono
''Acer pictum'' subsp. ''mono'', commonly known as painted maple or mono maple in English, or in Japan, wu jiao feng () in China, or gorosoe () or gorosoenamu () in Korea, is a species of maple.
Description
''Acer pictum'' subsp. ''mono'' g ...
in the caldera.
See also
*
Desert island
A desert island, deserted island, or uninhabited island, is an island, islet or atoll that is not permanently populated by humans. Uninhabited islands are often depicted in films or stories about shipwrecked people, and are also used as stereot ...
*
Lists of islands
This is a list of the lists of islands in the world grouped by country, by continent, by body of water
A body of water or waterbody (often spelled water body) is any significant accumulation of water on the surface of Earth or another plane ...