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Islanders asked to keep an eye out for researcher’s shark tag

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WE are used to unusual things washing up on Jersey’s beaches, but now Islanders are being asked to look out for a satellite tracker being used to study the behaviour of sharks.

D. Matthias Schaber

Researcher Matthias Schaber, from the German Thünen-Institute of Sea Fisheries in Bremerhaven, attached the satellite tag to a tope shark in the North Sea to record data for a study about the migration and behaviour patterns of the species.

After 270 days the tags detach from the shark, float to the surface and transmit the recorded data via satellite until the battery expires. However, more detailed data can be collected if a detached tag can be recovered.

One of the tags detached early, after four months collecting data, and started transmitting on 3 January near Guernsey and has been drifting around the Channel Islands since. According to tracking data, it travelled south from Guernsey to the Minquiers, then drifted north towards the Ecréhous before following Jersey’s east and north coasts. It then began to drift north again and last transmitted on 19 January from a position between Guernsey and Alderney.

Mr Schaber has now appealed for help to find the tracker, with a post on Facebook being shared over 150 times in 24 hours.

Speaking to the JEP, he said: ‘While the data that is recorded according to the pre-programmed schedule is transmitted, more high-resolution data with a higher sampling frequency is stored on the tag’s internal storage, like on a USB-stick. This dataset is too large to be transmitted via satellite, the battery of the tag will not allow this amount of data to be transmitted. So a recovery of the tag, even though this often is a bit unlikely, would contribute a significant amount of valuable scientific data that could then be physically downloaded.’

He added: ‘The reaction so far has been overwhelming: The request has been shared on Facebook in many similar and relevant groups and among private persons over 150 times within 24 hours. And while the physical recovery of those pop-up tags usually is an extreme and lucky exception from the rule, I am actually really optimistic that one day this tag may be found. Currently, there are four more tagged tope swimming around somewhere, and we will deploy further satellite tags in the summer – so depending on where those detach after their sampling period, there may be more tags to spot during beachcombing in the future.’

Anyone who finds the tag is asked to contact Mr Schaber via the information provided on the tag label or by emailing tags@thuenen.de.

Tope shark, which can grow up to two metres in length, are one of a number of species of shark found in Channel Island waters, along with the blue shark, basking shark and porbeagle shark. It is recognised as a vulnerable species and protected in British waters but there is a lack of data on the population living in the north-east Atlantic.

Lucy Stephenson

By Lucy Stephenson
author

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