Save Our Seas Blogs

In principle, there are two ways to equip sharks with acoustic tags: you can either attach the tags externally or internally. For both methods there are good examples to be found in the scientific literature. If done internally, you would usually catch the fish for surgical tag implantation. An alternative method can be feeding acoustic transmitters to sharks. Stomach tagging can be an interesting option and it allows you to, for example, monitor the stomach temperature of the animal in addition to obtaining presence-absence data. However, the indigestible tag will eventually be regurgitated, most likely via stomach eversion, and therefore tracking time is limited. In order to feed a tag to a shark, all you need is the tag wrapped in bait and a site where you know you can attract the sharks close enough to a feeder. There’s no better place than the Shark Reef Marine Reserve in Fiji to test the feasibility of stomach tagging and to estimate tag retention time. And so we did. The superb photograph on the right (taken by Klaus Jost) gives you an idea of how it looks when you hand-feed a tag to a good-sized bull shark in Fiji.

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