Tagging Tuna in the Coral Triangle



Posted on 07 November 2012  | 
The WWF Coral Triangle Global Initiative has set out to tag adult yellowfin tunas in the Philippines.

Over the past 2 weeks, 3 large yellowfin tunas caught by handline off the waters of Mindoro Occidental were tagged using a pop-up satellite tag, and released back. This is part of the 16 tags that will eventually be put in the water, anchored into the back portion of the fish just below the second dorsal fin.

Tagging activities are undertaken to better understand the behaviour of tunas: where and how long they stay in a particular water column any time of the day; how fast they swim; where they feed; and where they stay during their reproductive phase, among others. The results of the tagging will provide inputs into policies relating to the protection of these valuable species, such as the establishment of protected tuna spawning areas.

Once in the water, the pop-up tags automatically collect and store information on water temperature, depth, and amount of illumination from which its location is derived. The information is recorded every 30 seconds and stored in the tag. The tags automatically detach from the tuna after 4 to 6 months. Upon release, the tags will float to the ocean surface and send information using satellite technology to a server in Los Angeles, California.

The tuna handline fishery operates only during the dark phase of the moon--once the catching begins and the weather cooperates, the tagging will resume.

The first tagging event was hampered by uncooperative seas and the tunas didn’t take the bait. Hopefully, by mid November, we will have all the remaining tags in the water.

The tagging activity is supported by the Crown Family Foundation of the United States.
Tuna tagging in the Philippines
© Jose Ingles Enlarge

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