A basking shark satellite tag is still missing off the north coast of the Island.
The Manx Basking Shark Watch attached the device, worth £2000, on Wednesday, but if has since come off.
The charity has upped the reward fund for finding the tag to £200.
It is still floating 7-10 kilometres off-shore.
It is a similar shape to an ice-cream cone and has a red top about the size of a tennis ball.
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