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Twilight tag hunter

This is the incredible story of how a daring night-time expedition by sea kayak on Scotland’s remote west coast was rewarded by the recovery of a second satellite tag.

The story begins with the Irish Basking Shark Project deploying a number of satellite transmitters on basking sharks in early August 2014. These ‘SPOT’ transmitters are put on the sharks in order to track their surface movements both within and beyond Irish coastal waters. Over the past number of years the group have tried out a number of different tag designs but have felt the results were not sufficient, considering the cost of the transmitters.

In 2013, we thus decided to take matters into our own hands and make our own tag body out of high density foam from an old fishing float. Ironically, this design was not far off from that of the first GPS tracking tag ever deployed on a fish by Monty Priede. In 1982, Priede placed a ‘small boat’on a basking shark in the Clyde. Unusually, however, our tag was tested for hydrodynamics and robustness in a big bath by numerous young children. Surprisingly, it was also a remarkable success. Many more positions were recorded than during previous deployments, and the shark was tracked ‘live’ to the Azores before the tag detached.

For 2014, the team knew that our crude design needed to be refined for longer deployments. We brought in a team of experts with whom we had previously worked with on the basking shark Camera and accelerometer body deployment designs. Customised Animal Tracking Solutions (also known as CATS, or ‘Die Austrians in Oz’) will make your tagging dream into hard plastic if you are bold enough to ask. Using our basic ideas, they custom-made a number of tag bodies for us to deploy. The tags were deployed successfully in August 2014. Unfortunately, however, two tags prematurely detached after a period of 10 weeks. One tag was washed ashore, like so many of our ‘pop off’ TDR tags, on the Isle of Coll and quickly recovered by a local resident. The second tag was washed ashore during the January storms in a remote area of Scotland’s west coast, west of Arsaig and south of Mallaig. Now finding a person who is willing and able to search a remote area such as this during winter, braving its indented rocky coastline and savage tides, is not as easy as asking an islander to have a look in their back garden.

Justin Grant safely back at his car with the tag in hand © Justin Grant 2015

Amazingly, we found two separate teams of dedicated people willing to dare the west coast winter in their sea kayaks to help recover the tag: Mike Kingswood of the Arisaig Kayak Centre and Justin Grant of the Inverness Kayak Club. Mike undertook the first search in January but could not find anything. Remember folks: this tag is green, about 10cm by 5cm in size and most likely buried beneath a pile of seaweed. We calculated that there was roughly two million possible locations it could have been lying on the 1km by 10km stretch of coastline we could narrow the tags position to.

Last week, with improving weather conditions and calm seas, Suzanne Henderson of SNH recommended we try Justin Grant from the Inverness Kayak Club. We made contact and all seemed normal until we started to get emails asking about what frequency the tag was broadcasting on, and how many fixes we have had at the current location, and if we thought it was on the storm or spring tide line. It turns out Justin just happens to have his own Yaggi directional receiver for homing in on tag signals, has found eagle tags in the past and was unbelievably, if not suspiciously, organised at tag hunting.

Thus, last week Justin organised a team (not just one person to accompany him but a team!) to sacrifice their weekend, head to Mallaig and stay overnight before setting off in the early hours to search the stretch of coast. The kayakers spent the whole day searching the low tide, neap tide, spring tide and storm beach for signs of the tag, but as night fell even the tough had to sleep and the team headed back to their accommodation for some well-deserved rest. End of story, or so one would think. However, Justin, in his determination, had decided to sleep out all night until he could pick up a transmission on his Yaggi kit.

His perseverance did pay off and, against the odds, he got a signal at 3am and managed to determine the tag's location. It was well up on the storm beach amongst some grass, of all places - a location nobody would have thought of looking. Justin made it back to Mallaig the next morning for breakfast with a smile on his face and, I imagine, a weary body.

If the IBSSG gave medals, Justin would have the Bronze Plankton Star for his efforts. All of the dedication and time committed by Mike Kingswood and the Inverness Kayak Club, people who we don’t know and have never met, has re- boosted our determination to pursue the project to its logical conclusion and gain protection for the species in Irish and EU waters. Thank you to all involved - it has been an honour for us to have had you on our team for a short few days and we know now if we ever need a tag recovered in the future, all we need do is send up the ‘Justin Signal’ in a clear night sky.

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