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3 Miles in 3 Years

A recent beach clean-up organised at Malin Head has provided the answer to a mystery that has puzzled the Inishowen Basking Shark Study Group for the last 3 years. What happened to the 3 satellite tags we experimentally deployed on basking shark fins off Malin head? Did the sharks simply swim off and never return to the surface, or did the tags somehow fall off?

The simple answer seems to be the latter. It's likely that the tags got knocked off of the shark’s fins and laid on the bottom of the bay until being washed ashore at Culoort beach and found by the McGeoghegan family (Adrian, Conor, Niamh, Keira and Finley). The McGeoghegans were admirably doing their bit for the marine environment by helping out with the ‘Atlantic Beach Clean Up’ organised by local Dan Conaghan when they found the remains of the high-tech tag lying amongst seaweed.

McGeoghegan family with the found tag near their home at Malin head © E. Johnston 2017

The group had deployed the tag less than 3 miles from the beach at Culoort, Malin Head but failed to get any long-term returns from the three tags deployed using the experimental ‘Fin Mount’ method. Two of the tags have subsequently been recovered from nearby beaches without their fin clamps, indicating that the tags came off of their mountings. The group know that the tags were well-attached, so the possibility that the tags were ‘knocked off’ is something they are considering for future investigation.

This original mount idea emerged from the groups's dissatisfaction with existing ‘off the shelf’ tag designs. The rational about attaching the tag to the shark fin was first put forward by Dr. Simon Berrow because 1) the shark fin is out of the water more than any part of the body, and 2) it is also a very stable platform for tag transmission. Unfortunately, the tags didn’t provide any results and the group were forced to go back to the drawing board. Three different designs have been tested since that fateful year and each design has improved on the last.

If you find a tag on the beach please get in contact. It may hold valuable information the group can use to improve future designs and deployments.

With special thanks to Adrian, Conor, Niamh, Keira and Finley McGeoghegan who recovered the tag and helped solve our tag mystery.

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