Electronic tagging programme 

Figure 1. A pop-up satellite archival tag recovered during tagging operations off northwest Ireland in 2016.

We are tracking bluefin tuna movements from UK waters using both pop-up satellite archival tags and acoustic tags. Pop-up satellite archivel tags (PATs; Figure 1), are mounted externally and record ambient light, temperature and depth continuously every 15 seconds for up to a year. On a set date, the PAT tag detaches from the tuna and floats to the sea surface, it then begins to transmit a summary of the data to a satellite network. These tags are as small and light as current technology allows. Despite being only 20 cm long, they can collect data for up to one year, and transmit these data to satellites, but they store much more data on board that are very valuable if the tag can be physically recovered. We would therefore like to hear from anyone who may find these tags once they have detached from the tuna and washed ashore.

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THUNNUS UK is deploying up to 30 acoustic tracking tags (Figure 2; left) on bluefin tuna as part of the larger project, which will interface with a network of acoustic receiving stations (Figure 3) across Europe.

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Figure 3. An acoustic receiving station ready for deployment at the seabed.

Figure 2. A Thelma HP-16 acoustic tag (left) and a pop-up archival satellite tag (MiniPAT, right). Grid shows 1 cm sq.