Home > MAFF UPDATE > MAFF UPDATE No.741 (Published on November 9th, 2012) 


MAFF UPDATE No.741  (Published on November 9th, 2012)


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Confirmation of the first spawning of coral transplanted to Okinotori-shima (Okinotori Islands) 

Since 2006 the Fisheries Agency has implemented a coral transplantation project in Okinotori-shima, to promote the development and establishment of coral reproduction technology, and also spread it to other areas. In this project, the Fisheries Agency observed the first spawning of coral transplanted to Okinotori-shima in May 2008.


1. Overview of this project

(1)Overview of this project

Since FY2006 the Fisheries Agency has implemented "Coral reproduction in technological development and verification projects under harsh environmental conditions”. The following is a series of verification experiments and the technological development of this project. 

 ・After the coral parents were taken from Okinotori-shima, they were transplanted to a land seed
     reproduction facility in Okinawa, which is located 1,100 km by boat away from Okinotori-shima
 ・ Reproduction of coral eggs by sexual reproduction with the coral parents
 ・ Eggs are cultivated to become young corals by artificial breeding for one year
 ・ The young corals are transplanted on the rock reef in Okinotori-shima, or implemented on the artificial coral reproductive reef developed and 
     installed by this project
 ・ Conservation/Monitoring


(2)Confirmation of spawning of transplanted coral  

In June 2012, we conducted a field survey on transplant operation of young corals cultivated by artificial feeding for one year, and also the growth status, mortality-
whitening and spawning of corals which were transplanted after 2008, as well as corals living in and around there.


In this survey, the Fisheries Agency confirmed that large amounts (the number of implanted devices is about 1,600) of young corals were implanted and grown on the implanted devices developed by this project, and also that the natural corals implanted grew on the artificial coral reproductive reef.

In particular, after confirming eggs (bundle) (Photo 2) in polyps in Acropora tenuis (Photo 1) which grew to about 16 ~ 17cm among the coral species transplanted in May 2008, they were transferred to an observation tank on board. Finally, the Fisheries Agency was able to visually observe spawning (about 100 eggs) (Photo 3) on June 11, 2012. (Survey status: Photo 4 and 5)


The details of these investigations were reported to the Committee held on October 24, 2012, consisting of experts such as academics. They concluded that this was a great achievement leading to conservation and restoration of the coral reef ecosystems of Okinotori-shima, due to the fact that the transplanted coral grew to become spawning in the field.


The ecology of coral is a puzzle with many missing pieces, and it is still difficult to identify the timing of spawning; however, the Fishery Agency empirically estimated the seasonal spawning of Acropora tenuis by having repeatedly performing field surveys, and these have been very helpful for confirming spawning on this occasion.


              no741ishokusanngo            no741egg
    (Photo 1) Transplanted coral grew to about 17cm     (Photo 2) Confirmation of eggs in the polyp (bundle)



             (Photo 3) After eggs (bundle) were released from transplanted corals, spawning succeeded


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     (Photo 4) A mother ship (left) mooring out of reef in Okinotori-shima, A small vessel (right) investigating the reef


                  (Photo 5) A diver investigating the artificial coral rearing of Okinotori-shima

2. Future Plans

The Fisheries Agency will continue to focus on Okinotori-shima by developing a series of coral reproduction techniques such as seedling production on a variety of coral species, transplanting, conservation and monitoring, and then compile the results. The Fisheries Agency will thus assist conservation, and restore artificial breeding in Okinawa including other coral reefs in the coastal region by further developing these technologies.


Fisheries Infrastructure Department
Persons in charge:  Design Group:  Tsubota, Komori
Telephone Number: +81-3-3502-8111 (extension: 6880)
Dial-in: +81-3-6744-2390
Fax: +81-3-3502-2668




International Policy Planning Division 
International Affairs Department
Tel: +81-3-3591-9681
Fax: +81-3-5512-7652

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