was a Japanese tuna fishing boat with a crew of 23 men which was contaminated by nuclear fallout from the United States Castle Bravo thermonuclear weapon test at Bikini Atoll on March 1, 1954.
The crew suffered acute radiation syndrome (ARS) for a number of weeks after the Bravo test in March. All recovered from the immediate effects of the American test detonation except for Kuboyama Aikichi, the boat's chief radioman, who died on September 23, 1954, from complications of radiation sickness. Kuboyama is considered the first victim of the hydrogen bomb and of the Castle Bravo test.
Early days and final voyage Built in March 1947 and launched from Koza, Wakayama, the boat was originally named . It was a bonito boat and moored in Misaki Fishing Harbor, Kanagawa Prefecture. It was later remodeled into a tuna fishing boat. In 1953, it moved to Yaizu Port, Shizuoka Prefecture, with a new name, Daigo Fukuryū Maru, translated as Lucky Dragon No. 5 or the Fifth Lucky Dragon.
The Lucky Dragon No. 5 took five ocean voyages, the last of which began on January 22, 1954, and ended on March 14 of that year. The crew set off to go fishing in the Midway Sea near Midway Atoll, but when they lost most of their trawl nets to the sea, they altered their course southward near the Marshall Islands and encountered fallout from the Castle Bravo nuclear test at Bikini Atoll on March 1.
A map of the varying location of the boat in the days leading up to and after the day of the explosion is available. On March 1, the map depicts the vessel very near to the border of the US Navy issued "danger zone notice" dated October 10, 1953. Following March 1, the vessel charted a practically straight geodesic course back to its home port of Yaizu, passing the same latitude as Wake Island between March 4 and 6 and arriving at Yaizu on March 14.
The source of the map does not state how the map was created, that is, it does not state that the ship's log was consulted in the creation of the map, nor does it provide the navigator's measurements with the compass and sextant of the period. The exact position of the ship on the day of the explosion is therefore uncertain. Contemporary references give a figure of "80 miles (130 km) east of Bikini Atoll" without stating the method by which the distance was computed.Structure shielding against fallout gamma rays from nuclear detonations By Lewis Van Clief Spencer, Arthur B. Chilton, Charles Eisenhauer, Center for Radiation Research, United States. National Bureau of Standards, University of Illinois at Urbana-Champaign. pg 6Nasaizumi, Research in the effects and influences of the nuclear bomb test explosions, Volume 2 Japan. Committee for Compilation of Report on Research in the Effects of Radioactivity, Japan Society for the Promotion of Science, 1956 - History - page 1281 onwards of 1835 pages. According to a 1997 paper by Martha Smith-Norris, the ship was operating "14 miles" outside the 57,000 square mile "Danger Area", and it was not detected by radar or visual spotter planes.
Events surrounding March 1, 1954
The Daigo Fukuryū Maru (Lucky Dragon No. 5) encountered the fallout from the U.S. Castle Bravo nuclear test at Bikini Atoll, near the Marshall Islands, on March 1, 1954. When the test was held, the Daigo Fukuryū Maru was catching fish outside the danger zone that the U.S. government had declared in advance. However, the test was more than twice as powerful as predicted, and changes in weather patterns blew nuclear fallout, in the form of a fine ash, outside the danger zone. On that day, the sky in the west lit up like a sunset. The Daigo Fukuryū Maru was not damaged by the shock wave from the blast. However, several hours later white, radioactive dust made up of radioactive particles of coral and sand fell upon the ship. The fishermen attempted to escape from the area, but they took almost six hours to retrieve fishing gear from the sea and process fish (mainly shark and tuna) caught on the lines, exposing themselves to the radioactive fallout. The fishermen scooped the highly radioactive dust into bags with their bare hands. One fisherman, Oishi Matashichi, reported that he "took a lick" of the dust that fell on his ship, likening the falling material to 粉雪 ("powdered snow") and describing it as gritty but with no taste. The dust stuck to their bodies and the ship, entering their nasal passages and ears, irritating their eyes and collecting inside their underwear. Radiation sickness symptoms appeared later that day. Due to this, the fishermen called the white ash shi no hai (死の灰, death ash). The ash that fell upon the ship carried strontium-90, cesium-137, and uranium-237.Schreiber, Mark, "Lucky Dragon's lethal catch ", Japan Times, March 18, 2012, p. 7.
Events between March 2 and 14
During their return, the crew began showing symptoms of radiation poisoning as early as the evening after exposure. They experienced pain, headaches, nausea, dizziness, and diarrhea. Their eyes began to turn red and developed an itchy mucus. One crewman decided to keep some of the ash in order to have it analysed on their arrival home, but it was kept in a pouch hung from one of the bunks and was therefore in close proximity to the sleeping men for the duration of their return. Later analysis of the sample by, among others, Tokyo University determined that the ash was caused by a hydrogen bomb. The announcement of this news came as a large surprise to the Americans as they had persistently kept their nuclear experimentation secret.
By the third day, the men began to develop small blisters on their bodies where they had been touched by the radioactive ash. Their faces also began to turn dark. A week into their return journey, their hair began to fall out. On March 11, the ship encountered rough seas causing them to dock late on March 14. This late arrival fortunately caused the contaminated fish to stay within the ship until the next morning. Thus, they were able to throw away much of the tuna once they discovered the radiation.
Events after return to Yaizu port
After their arrival, the men went to the Yaizu Public Hospital, where the surgeon, Oi Toshiaki, applied a zinc ointment to their faces and sent them home. On March 15, 1954, engineer Yamamoto, deckhand Masuda, and 5 others who were said to make up the "elderly" crew members were sent to the Tokyo University Hospital for treatment. There, they tested Masuda's bone marrow and found his white blood cell count at half the normal level. Japanese biophysicist Nishiwaki Yasushi immediately traveled from Osaka to Yaizu to examine the crew and their boat. He quickly concluded that they had been exposed to radioactive fallout and wrote a letter to the chief of the US Atomic Energy Commission (AEC) asking for more information on how to treat the crew. The crew members, suffering from nausea, headaches, burns, pain in the eyes, bleeding from the gums, and other symptoms, were diagnosed with acute radiation syndrome. The US did not respond to Nishiwaki's letter or letters from other Japanese scientists requesting information and help. However, the United States did dispatch two medical scientists to Japan to study the effects of fallout on the ship's crew and to assist their doctors. The remaining crew members were quarantined in Yaizu North Hospital with all of their clothes and belongings buried on the property. High levels of radiation were found in the men's hair and nails, and so the hospital was forced to cut off the rest of their hair.
There is a hint of criticism from one of the crewmembers, Oishi Matashichi, aimed at the then Japanese Foreign Minister Katsuo Okazaki in his book, citing the fact that despite the lingering resentment towards the US over the atomic bombings of Hiroshima and Nagasaki in 1945, and the suspicion that US officials were only interested in research rather than attempting to cure anyone of their subsequent bombing-related ailments, Foreign Minister Okazaki is said to have spoken frequently to the crew about the need for the Americans to be present during treatment. Indeed, Oishi goes as far as to say "The Foreign Minister usually stood on the American side, and it appeared that he was the American Foreign Minister (rather than our own)."
The men were all transferred to the Tokyo University Hospital. There, they would remain for 14 months or more in some cases. They were subjected to daily examinations and multiple blood samples. Bone marrow was also drawn from different parts of their bodies. Their red and white blood cells had dropped significantly, causing internal bleeding and bloody stools. They had constant high fevers, bled from their noses and gums, and had persistent diarrhea. Their sperm counts also fell to low numbers or, in some cases, to none. For their treatment, the men were prescribed bed rest and given large quantities of antibiotics and blood transfusions. Dr. Morita Hisao reported that the men had developed acute panmyelosis, a disease that attacked their bone marrow, destroying its ability to generate blood.
Around August 20, Kuboyama Aikichi's condition deteriorated. By August 29, he fell into critical condition after developing meningitis. He became delirious and violent, having to be tied to a bed on the floor. Kuboyama soon fell into a coma and developed pneumonia. On September 23, he became the first member of the crew to die from complications of radiation sickness. The remaining 22 crew members were released from the hospital on May 20, 1955, after 14 months. They received yearly checkups to monitor the toll of long-term radiation sickness complications.
Health history of the surviving crew Like the hibakusha, survivors of atomic bombings in Hiroshima and Nagasaki in 1945, the Daigo Fukuryū Maru crew were stigmatized because of the Japanese public's fear of those exposed to radiation (it was commonly believed to be contagious). The crew tried to stay quiet about their exposure for decades, beginning with their discharge from the hospital. Some crew members moved away from their homes to make a fresh start. However, unlike the hibakusha, the Lucky Dragon No. 5 crew did not qualify for the medical care benefits that the survivors of the atomic bomb were given.
After being released from the hospital, Oishi Matashichi left his hometown to open a dry cleaning business. Beginning in the 1980s, he frequently gave talks advocating nuclear disarmament. His first child was stillborn, which Oishi attributed to his exposure to radiation. In 1992, Oishi developed cirrhosis of the liver but recovered after successful surgery. In 2011, he published a book titled, The Day the Sun Rose in the West: Bikini, the Lucky Dragon and I in English. The book combines his personal story, the story of the Daigo Fukuryū Maru, and declassified documents regarding communications between the Japanese and American governments about the fallout's damage. Former crew member Susumu Misaki opened a tofu shop after the incident. He died of lung cancer in Shizuoka Prefecture at the age of 92. Another crew member, Masayoshi Kawashima (川島正義), tried to earn a living making pouches after his release from the hospital, but it failed. Issues in his personal life led to a divorce. Kawashima returned to fishing but died soon after aged 47.
Crew member Sanjirō Masuda (増田三次郎) died aged 54 after contracting various illnesses and diseases, including cirrhosis of the liver, sepsis, stomach ulcers and diabetes. Crew member Yūichi Masuda (増田祐一) collapsed suddenly while working in a field and died less than 10 days later. Again, cirrhosis of the liver was cited as a cause.