you're reading...


Juvenile Pacific albacore party where the activity is hot: Studying the links between Fukushima-derived radionuclide distribution and fish migration

Article: Neville, D.R.; Phillips, A.J.; Brodeur, R.D.; Higley, K.A. (2014) Trace levels of Fukushima disaster radionuclides in East Pacific albacore. Environmental Science & Technology, 48:4739-4743.  DOI:10.1021/es500129b

Figure 1: March 11, 2011 magnitude 9.0 earthquake (red target) and location of Fukushima Daiichi nuclear reactor (black and yellow radiation symbol) (Source:  http://www.whoi.edu/website/fukushima-symposium/overview)

Figure 1: March 11, 2011 magnitude 9.0 earthquake (red target) and location of Fukushima Daiichi nuclear reactor (black and yellow radiation symbol) (Source)


As you all might recall, there was a wee bit of an earthquake (magnitude 9.0) in the western Pacific that occurred on March 11, 2011, resulting in a tsunami that caused the destruction of the Fukushima Daiichi nuclear plant in Japan (Figure 1). The explosions from three reactor buildings released a substantial amount of radioactive particles into the atmosphere and ocean, including the fission products Cesium-134 and Cesium-137 (134Cs and 137Cs). These cesium particles subsequently made their way into the food chain and were found in biota up to 600 meters offshore of the nuclear plant within one month of the accident. However, it has been estimated that surface ocean currents won’t transport the liquid plume with radionuclides from Fukushima to United States waters until 2014-2016.

But, ocean currents aren’t the only mechanism of radionuclide transport to the eastern Pacific. Some fish species are known to make trans-Pacific migrations. One such species is the Pacific albacore (Figure 2), which, between the ages of 2 and 5 years old, migrates annually between Japan and the United States. A survey of Pacific albacore conducted off the coast of Oregon and Washington every summer from 2008 to 2012 was able to show that not only was radiocesium present in Pacific Albacore, but that there were significant differences between pre-Fukushima fish and post-Fukushima fish.

Figure 2: Pacific Albacore (Source: http://www.fishwatch.gov/seafood_profiles/species/tuna/species_pages/pacific_albacore_tuna.htm)

Figure 2: Pacific Albacore (Source)

A total of 7 albacore from 2008, 2 from 2011, and 17 from 2012 were ashed and counted on a high purity germanium gamma spectrometer. Although 137Cs was present in all fish sampled, 134Cs was only detected in fish collected after March 2011. 134Cs is primarily produced in nuclear fuel, but it is not released by U.S and Canadian reactors; therefore, any presence in albacore samples is assumed to be solely derived from Fukushima contamination. 134Cs has a half-life of only 2 years and the ratio of 134Cs/137Cs released from Fukushima is believed to be 1:1 (one-to-one), so, any 137Cs unaccounted for in the albacore samples after ratio corrections was attributed to pre-Fukushima levels (Figure 3).

Figure 3: Non-Fukushima 137Cs (“Activity” on y-axis) were similar between both fish exposed to Fukushima-derived radiation (years 2011 and 2012, especially age 4 fish) and unexposed fish (2008).

Figure 3: Non-Fukushima 137Cs (“Activity” on y-axis) were similar between both fish exposed to Fukushima-derived radiation (years 2011 and 2012, especially age 4 fish) and unexposed fish (2008).

These findings are great for providing insight into the mechanisms of radionuclide transport and show that fish can introduce nuclear contamination to different regions of the ocean well before ocean currents can. As a bonus, this research is also useful for inferring migration patterns of Pacific albacore caught along the U.S. Pacific Northwest coast. Not all of the fish caught after March 2011 contained 134Cs, indicating that some fish had not been exposed to Japanese waters. This could be due to migration pattern and age. Juvenile albacore departing the U.S. coast have been observed to undergo five different migration patterns, only one of which brings them to Japanese waters. Additionally, the data from this study show a strong relationship between age and inferred migration near Japan. Since Pacific albacore migrate across the Pacific between the ages 2 and 5 years, fish that are only 2 years old are less likely to have been exposed to Japanese waters than those that are 3 or 4 years old. While both 3 and 4 year old fish caught in the summer of 2012 would have had two opportunities to migrate to Japan and back since the 2011 earthquake, it is possible only the 4 year old fish had actually made the trip twice since 3 year old fish were found to have lower 134Cs concentrations (Figure 4). However, it must be clarified that this study does not determine whether these concentration differences between ages are due to differences in migration patterns (i.e. exposure) or simply age-based ability to accumulate heavy metal contaminants (metabolism).

134Cs in Pacific albacore

Figure 4: Differences in 134Cs activity (y-axis) in Pacific albacore based upon fish age. Age 4 fish were bigger and exhibited higher 134Cs activity.


This study found that the radiocesium in exposed Pacific albacore was only about 0.1% of the U.S. Food and Drug Administration level of concern, and therefore does not appear to be significant to food safety. Such fish monitoring can help us track radionuclide transport from the Fukushima-Daiichi disaster and provide insight into Pacific albacore migration routes by using radionuclides as tracers. Future work will include sampling of both northern and southern U.S. albacore fisheries to see if radionuclides in the fish can help establish migration patterns. It is currently hypothesized that the north and the south are actually two different stocks of fish, with only the northern substock migrating to Japan.





No comments yet.

Post a Comment


  • by oceanbites 2 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 3 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 4 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 5 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 7 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 8 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 9 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 9 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 10 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 10 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 11 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 11 months ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com