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December 2012 Issue

Fish Near Fukushima’s Damaged Nuclear Plant Still Contaminated
The majority of fish caught off the northeast coast of Japan remain below limits for seafood consumption, even though the Japanese government tightened those limits in April 2012, Woods Hole Oceanographic Institution (WHOI) marine chemist Ken Buesseler found after analyzing data made publicly available by the Japanese Ministry of Agriculture, Forestry and Fisheries on radiation levels in fish, shellfish and seaweed collected at ports and inland sites in Fukushima Prefecture.

Nearly 9,000 samples describe the complex interplay between the marine environment and radionuclides released from the Fukushima Dai-Ichi nuclear power plant following the 2011 Tohoku earthquake and tsunami.

Buesseler’s findings, published in October in Science, also point out that the most highly contaminated fish continue to be caught off Fukushima prefecture’s coast and that bottom-dwelling fish consistently show the highest level of contamination by a radioactive isotope of cesium from the damaged nuclear power plant. Additionally, levels of contamination in almost all classifications of fish are not declining, although not all types are showing the same levels, and some are not showing any appreciable contamination.

Buesseler concludes that there may be a continuing source of radionuclides into the ocean, either in the form of low-level leaks from the reactor site itself or contaminated sediment on the seafloor. In addition, the varying levels of contamination across fish types points to complex methods of uptake and release by different species, making regulation and communication of the reasons behind decision making to the fish-hungry Japanese public all the more difficult.

“What we really need is a better understanding of the sources and sinks of cesium and other radionuclides that continue to drive what we’re seeing in the ocean off Fukushima,” Buesseler said.

Wideband Echosounder Works on 100 Frequencies Simultaneously
Norwegian researchers are finishing the development of a wideband echosounder that works on 100 frequencies simultaneously, making it much easier to identify fish and zooplankton.

Research vessels and many fishing vessels typically use echosounders that send and receive signals on up to six frequencies. Currently, multiple echosounders working in parallel on different frequencies are needed to identify marine organisms below the surface. A specific target can be singled out by analyzing all the elements within the echosounder image and removing the echoes from other species.

The project WESTZOO (Exploiting new wideband echosounder technology for zooplankton characterization, sizing and abundance estimation) has received funding from the Research Council of Norway.

Initially, the project researchers focused on zooplankton, since the echo from these marine organisms was well suited to the available frequency band. Later, they tried out the wideband echosounder on fish and other targets.

The echosounder will be launched in 2013, commercialized by Simrad (Horten, Norway).

In addition to the echosounder, WESTZOO researchers have developed a stereo camera method for photographing organisms being measured in ocean depths. The photos are used to verify the patterns and data detected by the echosounder. The researchers also created an acoustic probe to quantify and distinguish fish and plankton down to depths of 1,500 meters.


EU’s DEVOTES Aims to Improve Marine Monitoring Strategies
The European Union (EU) in November launched the DEVOTES (DEVelopment Of innovative Tools for understanding marine biodiversity and assessing good Environmental Status) project, which aims to explore how marine biodiversity is measured and to support the development of cost-effective systems in monitoring and management strategies.

The four-year DEVOTES project, which has a€12 million fund, involves more than 250 scientists in 23 research centres from 12 EU countries, as well as Ukraine, Turkey, Saudi Arabia and the U.S. Ángel Borja, principal investigator at AZTI-Tecnalia’s marine research division, will coordinate the project.

The scientists will develop and validate innovative tools that relate to ecological theory and assessment. These include remote sensing, modeling and genomics. The goal is to advance the understanding of the changes in ecosystems and biodiversity.

With the information and products generated during the DEVOTES project, the researchers will propose to the European authorities some measures contributing to the sustainable use of seas and marine resources.


Tagging Research Reveals Tracks Of Mako Shark in High Resolution
A satellite-reporting tagging device known as a Smart Position and Temperature (SPOT) tag, attached to a shortfin mako shark in New Zealand, is providing scientists previously unknown details of the species’ timing and long-distance migratory movements.

As of November, the juvenile shark had traveled 5,700 miles in five months, averaging 60 miles per day.

The Guy Harvey Research Institute (GHRI) at Nova Southeastern University is collaborating with the New Zealand National Institute of Water and Atmospheric Research (NIWA) on the tagging experiment with Carol, the shortfin mako shark.

The SPOT tag revealed the shark spends a lot of time at the ocean surface, reporting its location to the satellite several times daily. The shark’s movements are tracked at www.nova.edu/~johnmatt/makosharks.htm.

“Conventional identification tags tell us little about the timing of mako shark movements, the route that they take or distance traveled,” said Malcolm Francis, who is leading the NIWA effort on this study.

Since makos are often fished for their fins and meat, their population trends are declining in parts. They are listed as vulnerable on the International Union for Conservation of Nature Red List of threatened species.

The GHRI and NIWA plan to expand this study off New Zealand starting in January 2013. The GHRI is working with Keen M International (Isla Mujeres, Mexico) to compare the migratory patterns of mako sharks in the Atlantic by tagging them off Isla Mujeres.


2013:  JAN | FEB | MARCH | APRIL | MAY | JUNE | JULY | AUG | SEPT | OCT | NOV | DEC
2012:  JAN | FEB | MARCH | APRIL | MAY | JUNE | JULY | AUG | SEPT | OCT | NOV | DEC

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