Affects of Radioactive Levels from Fukushima on Fish

by Zoe Hurley on February 18, 2014

As population levels rise, it is becoming increasingly difficult to find food sources that can sustain the entire global population. Grain and farmland expansion is slowing to  stagnant levels and grazing land for cattle and other animals is also running out. One solution that has arisen is to look to the ocean. Fish has become an increasingly popular form of protein and aquaculture is on the rise. The ocean’s ecosystem, however, can be distressed by water pollution. After the April 2011 earthquake and tsunami in Fukushima, Japan, alarming levels of radioactive waste have been dumped into the water. This has lead to the question of how radioactive materials affect the aquatic environment, particularly how much will be absorbed by fish and other wildlife. If fish become dangerously radioactive, then food supply will dramatically drop. One fish in particular, the Yellow-Fin Tuna, is facing a major risk of becoming inedible due to the radioactive levels in their bloodstream and because their migratory pattern follows the path the radioactive materials are traveling.


Fish Caught off the Coast of Japan

Following the Fukushima Daiichi disaster, many people have worried about the radioactive levels present in the water as well as in fish that are consumed. Since the 1950s, radioactive materials have been found throughout the ocean thanks to radioactive plants dumping their wastes into the water. Some examples of this are the  British nuclear fuels plant dumping into the Irish sea, the French plants dumping into the English Channel, and the Soviets dumping their wastes into the Arctic Ocean, the Kara Sea, and the Barents Sea. Even though these wastes have been polluting the ocean for many years, there is still very little information about the effects. Organisms that have been studied in the Irish sea have indicated that previous releases of radioactive waste does not travel with ocean currents. Instead, the waste is deposited into marine sediment, which is then eaten and absorbed by organisms. This results in radioactive material climbing the food web. In this case, fish, especially tuna, are swimming through and eating radioactive materials then swimming across the Pacific Ocean toward California.

The radioactive material that is cause for concern is both short-lived and long-lived. Short-lived radioactive material includes iodine-131. Iodine is absorbed by the thyroid and while deficiencies can cause metabolic problems, radiation levels can also cause the thyroid to stop functioning. This stops the body from metabolizing food and can range from mild symptoms such as fatigue and weight gain, to more serious symptoms including effects such as brain damage and mental retardation. Long-lived radioactive material includes Cesium-137. Cesium acts similarly to potassium and is therefore very easily absorbed. Cesium’s half-life is 30 years and can therefore stay in the ocean, as well as fish, for this amount of time. Large doses of cesium have been linked to death, cancer, or genetic damage.

Lack of research concerning how radioactive materials are absorbed by organisms and then transferred to humans is cause for great concern, especially since the earthquake. Many people are worried about buying seafood, particularly tuna, that has come from Japan and the West Coast. Immediately after the disaster Japan implemented a temporary fishing ban. Many other countries have issued bans on using products from the ocean near the site of the disaster. In particular, the US has barred food from the Fukushima region the Food and Drug Administration is closely monitoring all food products from Japan. Even with these bans, Japan only implemented a standard for radioactive levels in seafood on April 5, 2011 and the levels that are dangerous versus negligible are still unknown.


Soon after the disaster the levels in fish were measured and the levels found in tuna were still considered safe to consume, although levels in small fish were considerably higher. Since the disaster, the radioactive levels in fish have been continuously monitored and a year after the disaster the levels found in tuna were so negligible that when compared to other foods the fish had lower levels than those found in a typical banana. With these statistics, tuna and other fish found in the Pacific Ocean appear to be safe to eat, but the presence of radioactive material is in itself alarming. However,  because fish who have ingested the radioactive sediment have been migrating toward California, the levels in all fish caught will have to be continuously monitored for years to come because they have been gradually rising.  The levels will be especially critical within the next few months, as the radioactive fish present at the time of the disaster are expected to reach the west coast of California where a large majority of Yellow Fin Tuna are harvested. Whether this will affect the global fish market is yet to be known. If radioactive levels in tuna continue to rise the fish industry will have to begin to rely on other sources of fish to supplement this major loss of food. Only time can tell whether this will occur, but if it does it will most certainly affect global food supply and slow down the use of fish as a food source combat world hunger.




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