Japan’s Sharks and Rays tested on Radioactivity

The Effect of the Fukushima Nuclear Disaster
on the Elasmobranch Fauna in Japan

 

 Helmut Nickel, Shark Year Magazine,
01. June 2012

The following list provides an update on our post from October 2011
Radioactive Materials found in Elasmobranchs in Fukushima Japan.

Below are the latest results of the tests for radioactive Caesium (Caesium-134 and Caesium-137) found in muscle tissue of elasmobranch species (sharks, skates and rays).

‘Shark Year Magazine’ has obtained these analytical results from the latest (April/May) publications of the Japanese Fisheries Agency.

 

According to the source, the Japanese standard limit for radioactive Caesium in fish is 100 Bq/kg.

The ocellate spot skate is the only one of the nine elasmobranch species which exceeded this limit ( in 18 of the 32 samples ). All these samples were collected from skates that had been caught in the waters of the Fukushima Prefecture.

For comparison: In the European Union, the current limit applying to imports of food (except liquid foods) from Japan is 500 becquerels per kilogram (Bq/kg).

The origin of the majority of the samples of ocellate spot skates was the Fukushima Prefecture.

All samples of pelagic shark species (salmon, blue, mako and thresher shark) were collected from offshore Pacific areas and later reported from the Miyagi Prefecture.

The two mottled skate samples came from the Hokkaido Prefecture in the north of the country, and the three tissue samples of the red stingray were collected from waters of the Ibaraki Prefecture.

 List of Analytical Results :

Pelagic Shark Species

Origin: Offshore ( Miyagi Prefecture ).
Sampling Date: 20. Februar – 23. March 2012.
Species: Salmon shark ( Lamna ditropis ).
Radioactive Caesium (Bq/kg) : Not detectable.

Origin: Offshore ( Miyagi Prefecture ).
Sampling Date: 20. Februar – 23. March 2012.
Species: Thesher shark ( Alopias sp.)
Radioactive Caesium (Bq/kg): 0.65

Origin: Offshore southern Sanriku Region.
Sampling Date: 28. March 2012.
Species: Salmon shark ( Lamna ditropis ).
Radioactive Caesium (Bq/kg): 17

Origin: Offshore ( Miyagi Prefecture )
Sampling Date: 26. February – 21. March 2012.
Species: Shortfin mako shark ( Isurus oxyrinchus ).
Radioactive Caesium (Bq/kg): 1.2

Origin: Offshore ( Miyagi Prefecture )
Sampling Date: 26. February – 21. March 2012.
Species: Blue shark ( Prionace glauca ).
Radioactive Caesium (Bq/kg): 0.61

Origin: Offshore southern Sanriku Region
Sampling Date: 1. April 2012.
Species: Salmon shark ( Lamna ditropis ).
Radioactive Caesium (Bq/kg): 13

Origin: Offshore southern Sanriku Region.
Sampling Date: 2-3 April 2012.
Species: Salmon shark ( Lamna ditropis ).
Radioactive Caesium (Bq/kg): 20

Origin: Offshore ( Miyagi Prefecture ).
Sampling Date: 29 February-28 March 2012.
Species: Blue shark ( Prionace glauca ).
Radioactive Caesium (Bq/kg): 2.2

Origin: Offshore ( Miyagi Prefecture )
Sampling Date: 03-26 March 2012.
Species: Shortfin mako shark ( Isurus oxyrinchus ).
Radioactive Caesium (Bq/kg): 14

Origin: Offshore ( Miyagi Prefecture )
Sampling Date: –
Species:  Shortfin mako shark ( Isurus oxyrinchus ).
Radioactive Caesium (Bq/kg): 9.8

Origin: Offshore southern Sanriku Region
Sampling Date: 6-7 April 2012.
Species: Salmon shark ( Lamna ditropis ).
Radioactive Caesium (Bq/kg): 4.6

Origin: Offshore Hitachi and Kashima.
Sampling Date: 04-08 April 2012.
Species: Salmon shark ( Lamna ditropis ).
Radioactive Caesium (Bq/kg): 13

Origin: Offshore Hitachi and Kashima.
Sampling Date: 04-08 April 2012.
Species: Blue shark ( Prionace glauca ).
Radioactive Caesium (Bq/kg): Not detectable.

Origin:Offshore southern Sanriku Region.
Sampling Date: 13. April 2012.
Species: Salmon shark ( Lamna ditropis ).
Radioactive Caesium (Bq/kg): 11

Origin: Offshore southern Sanriku Region.
Sampling Date: 13. April 2012.
Species: Salmon shark ( Lamna ditropis ).
Radioactive Caesium (Bq/kg): 13

Origin: Offshore southern Sanriku Region.
Sampling Date: 13. April 2012.
Species: Blue shark ( Prionace glauca ).
Radioactive Caesium (Bq/kg): 1.4

Origin: Offshore southern Sanriku Region.
Sampling Date: 16. April 2012.
Species: Salmon shark ( Lamna ditropis ).
Radioactive Caesium (Bq/kg): 10

Origin: Offshore ( Miyagi Prefecture )
Sampling Date: 16. March – 15. April 2012.
Species: Blue shark ( Prionace glauca ).
Radioactive Caesium (Bq/kg): Not detectable.

Origin: Offshore southern Sanriku Region.
Sampling Date: 24. April 2012.
Species: Salmon shark ( Lamna ditropis ).
Radioactive Caesium (Bq/kg): 21

Origin: Offshore ( Miyagi Prefecture ).
Sampling Date: 28 March -20 April 2012.
Species: Shortfin mako shark ( Isurus oxyrinchus ).
Radioactive Caesium (Bq/kg): 12

Origin: Offshore Miyagi.
Sampling Date: 8. May 2012.
Species: Tiger shark ( Galeocerdo cuvier ).
Radioactive Caesium (Bq/kg): 0.79

Origin: Offshore southern Sanriku Region.
Sampling Date: 9. May 2012.
Species: Salmon shark ( Lamna ditropis ).
Radioactive Caesium (Bq/kg): 20

Origin: Offshore southern Sanriku Region.
Sampling Date: 14. May 2012.
Species: Salmon shark ( Lamna ditropis ).
Radioactive Caesium (Bq/kg): 3.6

Origin: Offshore ( Miyagi Prefecture ).
Sampling Date: 9. May 2012.
Species: Blue shark ( Prionace glauca ).
Radioactive Caesium (Bq/kg): 0.73

————

Skates

Origin: Offshore Hisanohama ( Fukishima Prefectur ).
Sampling Date: 2. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 640

Origin: Offshore Nakoso ( Fukishima Prefectur ).
Sampling Date: 2. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 140

Origin: Offshore Hirono ( Fukishima Prefectur )
Sampling Date: 26. March 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 380

Origin: Offshore Haramachi ( Fukishima Prefectur )
Sampling Date: 29. March 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 190

Origin: Offshore Haragama ( Fukishima Prefectur )
Sampling Date: 28. March 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 59

Origin: Offshore Matsushima (Miyagi Prefecture).
Sampling Date: 1. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 50

Origin: Offshore Hisanohama (Fukushima Prefecture).
Sampling Date: 9. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 630

Origin: Offshore Hirono (Fukushima Prefecture).
Sampling Date: 6. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 410

Origin: Shore of Watari ( Miyagi Prefecture ).
Sampling Date: 2. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 24

Origin: Offshore Karakuwa-osaki, Kesennuma City (Miyagi  Prefecture).
Sampling Date:5. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 5.2

Origin: Offshore Hitachi-naka City ( Ibaraki Prefecture ).
Sampling Date: 10. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 28

Origin: Offshore Tairafujima ( Fukushima Prefecture ).
Sampling Date: 15. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 72

Origin: Offshore Ena ( Fukushima Prefecture ).
Sampling Date: 16. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 160

Origin: Offshore Haramachi ( Fukushima Prefecture ).
Sampling Date: 10. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 140

Origin: Offshore Shinchi ( Fukushima Prefecture ).
Sampling Date: 11. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 57

Origin: Offshore Onagawa Bay ( Miyagi Prefecture ).
Sampling Date: 15. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): Not detectable.

Origin: Offshore Tairafujima (Fukushima Prefecture).
Sampling Date: 19. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 630

Origin: Offshore Nakoso (Fukushima Prefecture).
Sampling Date: 22. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 77

Origin: Offshore Hisanohama (Fukushima Prefecture).
Sampling Date: 22. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 410

Origin: Offshore Oarai Town (Ibaraki Prefecture).
Sampling Date: 25. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 21

Origin: Offshore Oarai Town (Ibaraki Prefecture).
Sampling Date:  25. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 28

Origin: Offshore Onagawa Bay (Miyagi Prefecture).
Sampling Date: 24. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): Not detectable.

Origin: Offshore Hiyama ( Hokkaido Prefecture ).
Sampling Date: 22. April 2012.
Species: Mottled skate (Raja pulchra).
Radioactive Caesium (Bq/kg): Not detectable.

Origin: Offshore Hisanohama ( Fukushima Prefecture ).
Sampling Date: 7. May 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 540

Origin: Offshore Haramachi ( Fukushima Prefecture ).
Sampling Date: 26. April 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 190

Origin: Offshore Hirono ( Fukushima Prefecture ).
Sampling Date: 7. May 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 360

Origin: Offshore Hirono ( Fukushima Prefecture ).
Sampling Date: 7. May 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 320

Origin: Offshore Tairafujima ( Fukushima Prefecture ).
Sampling Date: 9. May 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 680

Origin: Offshore Shinchi ( Fukushima Prefecture ).
Sampling Date: 9. May 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 140

Origin: Offshore Oarai Town (Ibaraki Prefecture).
Sampling Date: 14. May 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 39

Origin: Offshore Iburi (Hokkaido Prefecture).
Sampling Date: 10. May 2012.
Species: Mottled skate (Raja pulchra).
Radioactive Caesium (Bq/kg): Not detectable.

Origin:Offshore Yamamoto (Miyagi Prefecture).
Sampling Date: 16. May 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 57

Origin: Offshore Hisanohama (Fukushima Prefecture).
Sampling Date: 21. May 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 730

Origin: Offshore Hirono (Fukushima Prefecture).
Sampling Date: 14. May 2012.
Species: Ocellate spot skate (Okamejei kenojei ).
Radioactive Caesium (Bq/kg): 310

——————–

Spiny Dogfish

Origin: Offshore Tappi, Sotogahama Town ( Aomori Prefecture ).
Sampling Date: 24. April 2012.
Species: Spiny dogfish (Squalus acanthias ).
Radioactive Caesium (Bq/kg): Not detectable.

Origin: Sendai Bay ( Miyagi Prefecture ).
Sampling Date: 18. May 2012.
Species: Spiny dogfish (Squalus acanthias ).
Radioactive Caesium (Bq/kg): 7.7

—————

Stingrays

Origin: Offshore Hitachi-naka City ( Ibaraki Prefecture ).
Sampling Date: 10. April 2012.
Species: Red stingray (Dasyatis akajei).
Radioactive Caesium (Bq/kg): 51

Origin: Offshore Oarai Town ( Ibaraki Prefecture ).
Sampling Date: 25. April 2012.
Species: Red stingray (Dasyatis akajei).
Radioactive Caesium (Bq/kg): 19

Origin: Offshore Oarai Town ( Ibaraki Prefecture ).
Sampling Date: 14. May 2012.
Species: Red stingray (Dasyatis akajei).
Radioactive Caesium (Bq/kg): 64

Source: Japanese Fisheries Agency