Bikar Atoll
Encyclopedia
Bikar Atoll is an uninhabited atoll
in the Ratak Chain
of the Marshall Islands
. It is one of the smallest atolls in the Marshalls and located at 12°14′N 170°08′E. Due to its relative isolation from the main islands in the group, Bikar has a largely undisturbed flora and fauna that has been allowed to exist in a relatively pristine condition.
, and 115 kilometres (71.5 mi) north of Utirik
, the nearest inhabited atoll. The land area is 0.5 square kilometre (0.193051079296268 sq mi), surrounding a 37.4 square kilometres (14.4 sq mi) lagoon
. It consists of 6 islets.
s are Bikar, Jabwelo, Almani, Jabwelo and Jaboero. Bikar, the largest, reaches a height of 6 meters above sea level.
Based on the results of drilling operations on Enewetak
(Eniwetok) Atoll, in the nearby Ralik Chain of the Marshall Islands, Bikar may include as much as 4600 feet of reef material atop a basalt
rock base. As most local coral growth stops at about 150 feet below the ocean surface, such a massive stony coral base suggests a gradual isostatic subsidence of the underlying extinct volcano, which itself rises 10,000 feet from the surrounding ocean floor. Shallow water fossils taken from just above Enewetak's basalt base are dated to about 55 mya.
Low rainfall and high temperatures lead to arid conditions in which a fresh water Ghyben-Herzberg lens cannot form. The water at Bikar island is not as brackish as similarly arid Taongi Atoll, allowing coconut
s planted by visiting islanders from Utirik Atoll
to survive.
Like Taongi Atoll, the combination of an almost completely enclosed lagoon and waves driven over the reef by the prevailing northeastern trade winds results in the water level being perched some 0.5 m above the mean tide level.
, Lepturus repens
, Cocos nucifera
, Boerhavia repens
, Pisonia grandis
, Portulaca lutea
, Triumfetta procumbens, Tournefortia argentea and Scaevola sericea
, as well as areas of atoll scrub and vines. Much of the Pisonia forest noted in earlier surveys was devastated by a cyclone, perhaps Typhoon Mary in 1977. This is likely a naturally recurring event. A small number of coconut palms planted by visiting islanders survive. A 1952 survey found that they produced small nuts containing bitter milk.
Twenty-three species of birds were found in a 1969 survey, of which 19 were observed during a follow-up count in 1988. Species breeding in larger numbers that year included the Great Frigatebird
and Red-footed Booby
. Their numbers appear reduced due to the destruction of the Pisonia forests. Other breeding species include the Red-tailed Tropicbird
, White-tailed Tropicbird
, the Masked Booby
, Brown Booby
, White Tern
, Brown Noddy
, and Sooty Tern
.
Migrant birds include small numbers of the Ruddy Turnstone
, Wandering Tattler
, Bristle-thighed Curlew
, Lesser Golden Plover
, and Pacific Reef Heron.
Bikar is also a major nesting site for the endangered Green Turtle, over 250 nesting sites having been observed in 1988.
The Polynesian Rat
is common on Bikar and Jabwelo. By 1993, a "population explosion" of non-Polynesian rats had been noted on the atoll, most likely introduced by Asian fishing trawlers operating illegally in the vicinity of Bikar. This raised concerns for the important sea turtle and bird nesting sites.
The coral fauna lacks diversity and shows signs of frequent storm damage. The corals include several genera not seen at Taongi Atoll, and the diversity of fish is much greater, including the Two-spot red snapper, Humpback red snapper, Leopard grouper
, and Humphead parrot fish
.
Shellfish include the Black-lipped pearl oyster, Bear paw clam
, Maxima clam
, and the sea snail Trochus
. No marine mammals have been seen in the lagoon.
and Toke
, Bikar was traditionally the hereditary property of the Ratak atoll chain Iroji Lablab
. The exploitation of abundant sea turtles, birds, and eggs was regulated by custom, and overseen by the Iroji.
and its North American territories.
The French corvette Danaide, Capt J. de Rosamel, visited the atoll in August, 1840 during a hydrographical survey of islands in the Pacific.
During the late 1800s, Bikar was the subject of a number of commercial transactions related to the increasing German presence in the Marshall Islands. On January 12, 1880 Bikar was sold by Iroojs Jurtaka and Takular of Maloelap, and on June 19, sold by Irooj Lajikit and Tannara of Utirik to Adolph Capelle & Co. On December 18, 1883 the Atoll was sold to Deutsche Handels und Plantagengesellschaft. Spain
transferred sovereignty to the Empire of Germany in 1885, and in December, 1887 property rights were transferred to the Jaluit Gesellschaft.
In 1900, the Manchester
, a four masted steel hulled cargo ship of 2851 tons with a load of kerosene, went missing at sea between New York
and Yokohama
. Wreckage and signs of habitation were discovered on Bikar in 1901, suggesting that the ship had come to grief there, and that the survivors had pushed off in lifeboats shortly before the discovery. No sign of the crew or passengers has since been found.
occupied the Marshall Islands, and transferred German government properties to their own, including Bikar. Like the Germans before them, the Japanese colonial administration (the South Pacific Mandate
) did not attempt to exploit the atoll, and the Northern Radak Marshallese continued to hunt and fish unmolested. Following the end of World War II
, the island came under the control of the United States
as part of the Trust Territory of the Pacific Islands
. In 1951, the U.S. Geological Survey and the Army Corps of Engineers sponsored an expedition to Bikar and Taongi Atolls, to characterize their primeval environment.
While en route from the US to Asia in April, 1953, LST 1138, later commissioned as USS Steuben County, dropped anchor at Bikar to search for rumored Japanese stragglers
. The landing party found no signs of any current occupants.
In 1954, the fallout plume from the Castle Bravo
nuclear test passed over Bikar about 20 hours after the shot. Based on ash from plant samples taken on March 9, the atoll was contaminated by about 1,400,000 d/m/gm of radioactive material, compared with 35,000,000 d/m/gm from the most contaminated soil samples at Rongelap Atoll
, and 950 d/m/gm at Majuro Atoll, several hundred miles south of the fallout pattern. This experience led to a pre-planned aerial survey of atolls adjacent to the subsequent March 27 Castle Romeo
test, timed at one and four hours after the shot. The aircraft were equipped with gamma radiation detectors designed to measure ground contamination from altitudes of 200 to 500 feet. An overflight of Bikar Island measured 0.1 mrem
/hr (1 μGy
) an hour after the shot, rising to 15 mrem/hr (150 μGy) three hours later.
In 1962, 19 Japanese fishermen from the fishing boat Daitei Maru No. 15 were marooned on Bikar Atoll for several days before being rescued by the U.S. Coast Guard.
A 1981 study of fish and invertebrates within the lagoon found that the level of radio-nucleotides in muscle tissue was within the range found in fish products imported to the US and Japanese markets. The worldwide source of seafood-borne radio-nucleotides is a result of atmospheric nuclear testing since 1945, and therefore any residual activity from the 1950s Castle series of tests
contributes only a small fraction of the contamination within the lagoon's sea life.
Currently, no archaeological remains of Polynesian habitation have been identified. The almost completed corroded wreck of a Japanese fishing boat lies in the north fork of the reef passage.
Atoll
An atoll is a coral island that encircles a lagoon partially or completely.- Usage :The word atoll comes from the Dhivehi word atholhu OED...
in the Ratak Chain
Ratak Chain
The Ratak Chain is a chain of islands within the island nation of the Marshall Islands. Ratak means "sunrise". It lies just to the east of the country's other main island chain, the Ralik Chain...
of the Marshall Islands
Marshall Islands
The Republic of the Marshall Islands , , is a Micronesian nation of atolls and islands in the middle of the Pacific Ocean, just west of the International Date Line and just north of the Equator. As of July 2011 the population was 67,182...
. It is one of the smallest atolls in the Marshalls and located at 12°14′N 170°08′E. Due to its relative isolation from the main islands in the group, Bikar has a largely undisturbed flora and fauna that has been allowed to exist in a relatively pristine condition.
Geography
It is located 579 kilometres (359.8 mi) north of Majuro Atoll, the capital of the Marshall Islands, 320 kilometres (198.8 mi) South-southeast of BokakBokak Atoll
Bokak Atoll or Taongi Atoll is an uninhabited coral atoll in the Ratak Chain of the Marshall Islands, located in the North Pacific Ocean at...
, and 115 kilometres (71.5 mi) north of Utirik
Utirik Atoll
Utirik Atoll or Utrik Atoll is a coral atoll of 10 islands in the Pacific Ocean, and forms a legislative district of the Ratak Chain of the Marshall Islands. Its total land area is only , but it encloses a lagoon with an area of...
, the nearest inhabited atoll. The land area is 0.5 square kilometre (0.193051079296268 sq mi), surrounding a 37.4 square kilometres (14.4 sq mi) lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
. It consists of 6 islets.
Physical features
The approximately diamond-shaped atoll measures up to 13 km north to south and up to 8 km across. Its six islets have a combined land area of less than 0.5 square kilometre (0.193051079296268 sq mi) and enclose a shallow lagoon of 37 square kilometres (14.3 sq mi). The surrounding reef is continuous except for one narrow pass located on the western side. The major isletIslet
An islet is a very small island.- Types :As suggested by its origin as islette, an Old French diminutive of "isle", use of the term implies small size, but little attention is given to drawing an upper limit on its applicability....
s are Bikar, Jabwelo, Almani, Jabwelo and Jaboero. Bikar, the largest, reaches a height of 6 meters above sea level.
Based on the results of drilling operations on Enewetak
Enewetak
Enewetak Atoll is a large coral atoll of 40 islands in the Pacific Ocean, and forms a legislative district of the Ralik Chain of the Marshall Islands. Its land area totals less than , surrounding a deep central lagoon, in circumference...
(Eniwetok) Atoll, in the nearby Ralik Chain of the Marshall Islands, Bikar may include as much as 4600 feet of reef material atop a basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
rock base. As most local coral growth stops at about 150 feet below the ocean surface, such a massive stony coral base suggests a gradual isostatic subsidence of the underlying extinct volcano, which itself rises 10,000 feet from the surrounding ocean floor. Shallow water fossils taken from just above Enewetak's basalt base are dated to about 55 mya.
Low rainfall and high temperatures lead to arid conditions in which a fresh water Ghyben-Herzberg lens cannot form. The water at Bikar island is not as brackish as similarly arid Taongi Atoll, allowing coconut
Coconut
The coconut palm, Cocos nucifera, is a member of the family Arecaceae . It is the only accepted species in the genus Cocos. The term coconut can refer to the entire coconut palm, the seed, or the fruit, which is not a botanical nut. The spelling cocoanut is an old-fashioned form of the word...
s planted by visiting islanders from Utirik Atoll
Utirik Atoll
Utirik Atoll or Utrik Atoll is a coral atoll of 10 islands in the Pacific Ocean, and forms a legislative district of the Ratak Chain of the Marshall Islands. Its total land area is only , but it encloses a lagoon with an area of...
to survive.
Like Taongi Atoll, the combination of an almost completely enclosed lagoon and waves driven over the reef by the prevailing northeastern trade winds results in the water level being perched some 0.5 m above the mean tide level.
Climate
Bikar is one of the driest of the Marshall Islands atolls, having a semi-arid character. Mean annual temperature is approximately 82°F. Mean annual rainfall is less than 45", and falls primarily during the July through October rainy season. Prevailing winds are north to north-easterlies.Vegetation
Plant species of atoll forest include Pandanus tectoriusPandanus tectorius
Pandanus tectorius is a species of Pandanus that is native to Malesia, eastern Australia, and the Pacific Islands. Common names include Thatch Screwpine, Hala , Bacua , and Vacquois ....
, Lepturus repens
Lepturus
Thintail is a grass genus in the Poaceae family. The related monotypic genus Hainardia was formerly included in Lepturus. Species within this genus are often found in tropical or subtropical ecosystems; an example occurrence is on certain islands within the Great Barrier Reef in the Coral...
, Cocos nucifera
Coconut
The coconut palm, Cocos nucifera, is a member of the family Arecaceae . It is the only accepted species in the genus Cocos. The term coconut can refer to the entire coconut palm, the seed, or the fruit, which is not a botanical nut. The spelling cocoanut is an old-fashioned form of the word...
, Boerhavia repens
Boerhavia
Boerhavia, the spiderlings, is a genus of about 40 species of annual or perennial herbaceous plants in the four o'clock flower family, Nyctaginaceae. The common name refers to the appearance of a spider or spider's web given by the numerous long, slender and interlocking stems of the inflorescences...
, Pisonia grandis
Pisonia grandis
Pisonia grandis is a species of flowering tree in the Bougainvillea family, Nyctaginaceae.-Description:The tree has broad, thin leaves, smooth bark and bears clusters of green sweet-smelling flowers that mature into sticky barbed seeds....
, Portulaca lutea
Portulaca
Portulaca is the type genus of the flowering plant family Portulacaceae, comprising about 40-100 species found in the tropics and warm temperate regions. They are also sometimes known as Rose Moss or more commonly Moss Roses....
, Triumfetta procumbens, Tournefortia argentea and Scaevola sericea
Scaevola
Scaevola is a genus of flowering plants in the Goodenia family, Goodeniaceae. It consists of more than 130 tropical species, with the center of diversity being Australia and Polynesia, including Hawaii....
, as well as areas of atoll scrub and vines. Much of the Pisonia forest noted in earlier surveys was devastated by a cyclone, perhaps Typhoon Mary in 1977. This is likely a naturally recurring event. A small number of coconut palms planted by visiting islanders survive. A 1952 survey found that they produced small nuts containing bitter milk.
Fauna
Bikar's status as a major seabird nesting site was affected by a cyclone and the introduction of more aggressive rat species.Twenty-three species of birds were found in a 1969 survey, of which 19 were observed during a follow-up count in 1988. Species breeding in larger numbers that year included the Great Frigatebird
Great Frigatebird
The Great Frigatebird is a large dispersive seabird in the frigatebird family. Major nesting populations are found in the Pacific and Indian Oceans, as well as a population in the South Atlantic....
and Red-footed Booby
Red-footed Booby
The Red-footed Booby, Sula sula, is a large seabird of the booby family, Sulidae. As suggested by the name, adults always have red feet, but the colour of the plumage varies. They are powerful and agile fliers, but they are clumsy in takeoffs and landings...
. Their numbers appear reduced due to the destruction of the Pisonia forests. Other breeding species include the Red-tailed Tropicbird
Red-tailed Tropicbird
The Red-tailed Tropicbird, Phaethon rubricauda, is a seabird that nests across the Indian and Pacific Oceans. It is the rarest of the tropicbirds, yet is still a widespread bird that is not considered threatened. It nests in colonies on oceanic islands....
, White-tailed Tropicbird
White-tailed Tropicbird
The White-tailed Tropicbird Phaethon lepturus, is a tropicbird, smallest of three closely related seabirds of the tropical oceans and smallest member of the order Phaethontiformes. It occurs in the tropical Atlantic, western Pacific and Indian Oceans...
, the Masked Booby
Masked Booby
The Masked Booby, Sula dactylatra, is a large seabird of the booby family, Sulidae. This species breeds on islands in tropical oceans, except in the eastern Atlantic; in the eastern Pacific it is replaced by the Nazca Booby, Sula granti, which was formerly regarded as a subspecies of Masked Booby...
, Brown Booby
Brown Booby
The Brown Booby is a large seabird of the booby family, Sulidae. The adult brown booby reaches about in length. Its head and upper body are covered in dark brown, with the remainder being a contrasting white. The juvenile form is gray-brown with darkening on the head, wings and tail...
, White Tern
White Tern
The White Tern is a small seabird found across the tropical oceans of the world. It is sometimes known as the Fairy Tern although this name is potentially confusing as it is the common name of the Fairy Tern Sternula nereis...
, Brown Noddy
Brown Noddy
The Brown Noddy or Common Noddy is a seabird from the tern family. The largest of the noddies, it can be told from the closely related Black Noddy by its larger size and plumage, which is dark brown rather than black...
, and Sooty Tern
Sooty Tern
The Sooty Tern, Onychoprion fuscatus , is a seabird of the tern family . It is a bird of the tropical oceans, breeding on islands throughout the equatorial zone. Colloquially, it is known as the Wideawake Tern or just wideawake...
.
Migrant birds include small numbers of the Ruddy Turnstone
Ruddy Turnstone
The Ruddy Turnstone is a small wading bird, one of two species of turnstone in the genus Arenaria. It is now classified in the sandpiper family Scolopacidae but was formerly sometimes placed in the plover family Charadriidae...
, Wandering Tattler
Wandering Tattler
The Wandering Tattler, Tringa incana , is a medium-sized wading bird. It is similar in appearance to the closely related Gray-tailed Tattler, T. brevipes...
, Bristle-thighed Curlew
Bristle-thighed Curlew
The Bristle-thighed Curlew, Numenius tahitiensis, is a large shorebird that breeds in Alaska and winters on tropical Pacific islands. It has a long, decurved bill and bristled feathers at the base of the legs. Its length is about 43 cm and wingspan about 84 cm...
, Lesser Golden Plover
Pacific Golden Plover
The Pacific Golden Plover is a medium-sized plover.The 23–26 cm long breeding adult is spotted gold and black on the crown, back and wings. Its face and neck are black with a white border and it has a black breast and a dark rump. The legs are black...
, and Pacific Reef Heron.
Bikar is also a major nesting site for the endangered Green Turtle, over 250 nesting sites having been observed in 1988.
The Polynesian Rat
Polynesian Rat
The Polynesian Rat, or Pacific Rat , known to the Māori as kiore, is the third most widespread species of rat in the world behind the Brown Rat and Black Rat. The Polynesian Rat originates in Southeast Asia but, like its cousins, has become well travelled – infiltrating Fiji and most Polynesian...
is common on Bikar and Jabwelo. By 1993, a "population explosion" of non-Polynesian rats had been noted on the atoll, most likely introduced by Asian fishing trawlers operating illegally in the vicinity of Bikar. This raised concerns for the important sea turtle and bird nesting sites.
The coral fauna lacks diversity and shows signs of frequent storm damage. The corals include several genera not seen at Taongi Atoll, and the diversity of fish is much greater, including the Two-spot red snapper, Humpback red snapper, Leopard grouper
Mycteroperca
Mycteroperca is a genus of fish in the family Serranidae, subfamily Epinephelinae .It contains the following species:* Black grouper * Venezuelan grouper...
, and Humphead parrot fish
Parrotfish
Parrotfishes are a group of fishes that traditionally had been considered a family , but now often are considered a subfamily of the wrasses. They are found in relatively shallow tropical and subtropical oceans throughout the world, but with the largest species richness in the Indo-Pacific...
.
Shellfish include the Black-lipped pearl oyster, Bear paw clam
Bear paw clam
The bear paw clam, also known as the horse's hoof clam or strawberry clam, Hippopus hippopus, is a species of large saltwater clam, a tropical marine bivalve mollusk in the family Tridacnidae, the giant clam family.-Distribution:...
, Maxima clam
Maxima clam
The maxima clam , also known as the small giant clam, is a species of bivalve found throughout the Indo-Pacific. They are much sought after in the aquarium trade, as their often striking coloration mimics that of the true giant clam, however the maximas maintain a manageable size, with the shells...
, and the sea snail Trochus
Trochus
Trochus is a genus of medium-sized to very large sea snails. They are marine gastropod molluscs in the family Trochidae, the top snails....
. No marine mammals have been seen in the lagoon.
Prehistory
Although humans migrated to the Marshall Islands about 2000 years ago, and Bikar was occasionally visited by the Marshallese, there is no evidence that there has ever been a resident human population. The lack of water and the susceptibility of the atoll to cyclone and storm disturbance indicate that it will probably remain uninhabited. The atoll has traditionally been used for hunting and gathering, particularly sea birds and turtles, by inhabitants of other atolls in the northern Ratak chain. Along with the other uninhabited northern Ratak atolls of Bokak (Taongi)Bokak Atoll
Bokak Atoll or Taongi Atoll is an uninhabited coral atoll in the Ratak Chain of the Marshall Islands, located in the North Pacific Ocean at...
and Toke
Toke Atoll
Toke Atoll or Taka Atoll is a small, uninhabited coral atoll in the Ratak Chain of the Marshall Islands. It is one of the smaller atolls in the Marshalls and located at . It is visited regularly by the residents of nearby Utirik Atoll.- Geography :The atoll is north of Majuro Atoll, the capital...
, Bikar was traditionally the hereditary property of the Ratak atoll chain Iroji Lablab
Iroijlaplap
Iroijlaplap is the title given to the paramount chiefs in the Marshall Islands. An ordinary chief holds the title of Iroij ....
. The exploitation of abundant sea turtles, birds, and eggs was regulated by custom, and overseen by the Iroji.
19th century
The Russian brig Rurik, Captain Otto von Kotzebue, visited in the summer, 1817 during a search for a north passage between western RussiaRussian Empire
The Russian Empire was a state that existed from 1721 until the Russian Revolution of 1917. It was the successor to the Tsardom of Russia and the predecessor of the Soviet Union...
and its North American territories.
The French corvette Danaide, Capt J. de Rosamel, visited the atoll in August, 1840 during a hydrographical survey of islands in the Pacific.
During the late 1800s, Bikar was the subject of a number of commercial transactions related to the increasing German presence in the Marshall Islands. On January 12, 1880 Bikar was sold by Iroojs Jurtaka and Takular of Maloelap, and on June 19, sold by Irooj Lajikit and Tannara of Utirik to Adolph Capelle & Co. On December 18, 1883 the Atoll was sold to Deutsche Handels und Plantagengesellschaft. Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
transferred sovereignty to the Empire of Germany in 1885, and in December, 1887 property rights were transferred to the Jaluit Gesellschaft.
In 1900, the Manchester
Manchester (barque)
Manchester was a four-masted, steel-hulled British barque which was wrecked in late 1900 on the reefs of Bikar Atoll, Marshall Islands.-History:The Manchester was built at the shipyards of William Doxford & Sons in Sunderland, England in 1892...
, a four masted steel hulled cargo ship of 2851 tons with a load of kerosene, went missing at sea between New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
and Yokohama
Yokohama
is the capital city of Kanagawa Prefecture and the second largest city in Japan by population after Tokyo and most populous municipality of Japan. It lies on Tokyo Bay, south of Tokyo, in the Kantō region of the main island of Honshu...
. Wreckage and signs of habitation were discovered on Bikar in 1901, suggesting that the ship had come to grief there, and that the survivors had pushed off in lifeboats shortly before the discovery. No sign of the crew or passengers has since been found.
20th century to Present
In 1914, the Empire of JapanEmpire of Japan
The Empire of Japan is the name of the state of Japan that existed from the Meiji Restoration on 3 January 1868 to the enactment of the post-World War II Constitution of...
occupied the Marshall Islands, and transferred German government properties to their own, including Bikar. Like the Germans before them, the Japanese colonial administration (the South Pacific Mandate
South Pacific Mandate
The was the Japanese League of Nations mandate consisting of several groups of islands in the Pacific Ocean which came under the administration of Japan after the defeat of the German Empire in World War I.-Early history:Under the terms of the Anglo-Japanese Alliance, after the start of World...
) did not attempt to exploit the atoll, and the Northern Radak Marshallese continued to hunt and fish unmolested. Following the end of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, the island came under the control of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
as part of the Trust Territory of the Pacific Islands
Trust Territory of the Pacific Islands
The Trust Territory of the Pacific Islands was a United Nations trust territory in Micronesia administered by the United States from 1947 to 1986.-History:...
. In 1951, the U.S. Geological Survey and the Army Corps of Engineers sponsored an expedition to Bikar and Taongi Atolls, to characterize their primeval environment.
While en route from the US to Asia in April, 1953, LST 1138, later commissioned as USS Steuben County, dropped anchor at Bikar to search for rumored Japanese stragglers
Japanese holdout
Japanese holdouts or stragglers were Japanese soldiers in the Pacific Theatre who, after the August 1945 surrender of Japan that marked the end of World War II, either adamantly doubted the veracity of the formal surrender due to strong dogmatic or militaristic principles, or were not aware of it...
. The landing party found no signs of any current occupants.
In 1954, the fallout plume from the Castle Bravo
Castle Bravo
Castle Bravo was the code name given to the first U.S. test of a dry fuel thermonuclear hydrogen bomb device, detonated on March 1, 1954 at Bikini Atoll, Marshall Islands, as the first test of Operation Castle. Castle Bravo was the most powerful nuclear device ever detonated by the United States ,...
nuclear test passed over Bikar about 20 hours after the shot. Based on ash from plant samples taken on March 9, the atoll was contaminated by about 1,400,000 d/m/gm of radioactive material, compared with 35,000,000 d/m/gm from the most contaminated soil samples at Rongelap Atoll
Rongelap Atoll
Rongelap Atoll or Namorik Atoll is a coral atoll of 61 islands in the Pacific Ocean, and forms a legislative district of the Ralik Chain of the Marshall Islands. Its total land area is only , but it encloses a lagoon with an area of...
, and 950 d/m/gm at Majuro Atoll, several hundred miles south of the fallout pattern. This experience led to a pre-planned aerial survey of atolls adjacent to the subsequent March 27 Castle Romeo
Castle Romeo
Castle Romeo was the code name given to one of the tests in the Operation Castle series of American nuclear tests. It was the first test of the TX-17 thermonuclear weapon , the first deployed U.S...
test, timed at one and four hours after the shot. The aircraft were equipped with gamma radiation detectors designed to measure ground contamination from altitudes of 200 to 500 feet. An overflight of Bikar Island measured 0.1 mrem
Röntgen equivalent man
Named after Wilhelm Röntgen , the roentgen equivalent in man or rem is a unit of radiation dose equivalent...
/hr (1 μGy
Gray (unit)
The gray is the SI unit of absorbed radiation dose of ionizing radiation , and is defined as the absorption of one joule of ionizing radiation by one kilogram of matter ....
) an hour after the shot, rising to 15 mrem/hr (150 μGy) three hours later.
A 1981 study of fish and invertebrates within the lagoon found that the level of radio-nucleotides in muscle tissue was within the range found in fish products imported to the US and Japanese markets. The worldwide source of seafood-borne radio-nucleotides is a result of atmospheric nuclear testing since 1945, and therefore any residual activity from the 1950s Castle series of tests
Operation Castle
Operation Castle was a United States series of high-energy nuclear tests by Joint Task Force SEVEN at Bikini Atoll beginning in March 1954...
contributes only a small fraction of the contamination within the lagoon's sea life.
Currently, no archaeological remains of Polynesian habitation have been identified. The almost completed corroded wreck of a Japanese fishing boat lies in the north fork of the reef passage.