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Ori tag reveals the surprising age of a two oceans aquarium galjoen

- Blog
Ori tag reveals the surprising age of a two oceans aquarium galjoen

The Oceanographic Research Institute’s Cooperative Fish Tagging Project (ORI-CFTP) is long-term citizen science project in which anglers voluntarily tag and release the fish they catch. By monitoring and recording the information every time a fish is tagged or recaptured, ORI is able to collaboratively gather information about the fish and help inform conservation and sustainability decision making.

But, sometimes ORI tagged fish turn up in unusual situations! On 7 October, a recapture of a different nature took place - a galjoen in the Two Oceans Aquarium's Kelp Forest Exhibit.

Aquarium galjoen by Devon Bowen

This story begins on 1 September 2000 when, Simon Walker, one of ORI's top taggers, tagged and released a small galjoen at Pappies Bank near Cape Point in the Western Cape. Measuring 287mm fork length (from the tip of the snout to the middle of the tail), this galjoen was estimated to be 3-4 years of age. This fish was recaptured at the same place a year later by Simon Chater, measuring 315mm, during a collections trip for the Two Oceans Aquarium​.

Simon Chater remembers this day vividly, “We were fishing into the teeth of a SW gale and driving rain and I was catching them in shallow water on my Scarborough reel! I remember thinking at the time that this is what I had read typical galjoen fishing was like!”.

The galjoen was taken back to the Aquarium where it was kept in quarantine prior to being put on exhibit. The ORI tag was cut a bit shorter by the Aquarium team, so that it would not visibly stick out of the fish while on display and the fish was released into the Kelp Forest Exhibit.

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After 20 years at the Aquarium, the galjoen was taken out for a small surgery to remove a small “growth” - which turned out to be the original tag that had been grown over! The old tag was removed during the surgery and the ORI tag number was still visible. Two Oceans Aquarium Senior Collections Aquarist Simon Brill, contacted ORI asking for details on this tag - and this is when we learned some of the amazing information about this galjoen! This fish is now 480mm and 3.1kg, having grown 165mm at the Aquarium. Although the galjoen is healthy, our CEO Michael Farquhar speculates that it may have grown a bit slower than in the wild due to differences in diet.

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Based on the fish's age estimate at the time of its first tagging, it may be 25 years old now! This is 4 years older than the maximum age that has been estimated for galjoen based on reading sectioned otoliths (small ear bones that have growth rings like a tree)!

With the three “Simons” involved in this story, this special galjoen has been named “Simone” (a ‘she’ because the males are smaller and only live to approximately 12 years). Apart from being a fascinating little story, this “recapture” has provided valuable information for galjoen research and provides yet another example of why tagging is so important and the valuable information we can gather from it.

Michael Farquhar added: “In 2018 we repaired our Kelp Forest Exhibit and, in the process, all fish were removed and kept in quarantine for the repair process. Before being reintroduced to the exhibit, all reasonably sized fish were PIT-tagged, including this galjoen. So, although it no longer has the ORI spaghetti tag, we will be able to continue identifying this fish into the future should it be removed again from the exhibit.”

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The Two Oceans Aquarium would like to encourage all anglers to support ORI-CFTP, and in turn, support the sustainable use and conservation of our marine species. ORI is a division of the South African Association for Marine Biological Research (SAAMBR), and together produce some fantastic resources about our ocean - check out their new ORI Fish App Marine Fish Guide for Southern Africa. Keep up the good work SAAMBR!

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