Barracuda on tour
Thursday, 30 May 2024
The collection in the 'Little Ocean' — the basin on the left before the ray tunnel — needs replenishing, as the golden trevally and barracuda are now twenty years old. The barracuda pose a problem, however, as they would attack smaller fish. The Ocean team considered moving the barracuda to the shark tank, but this would make individual feeding of the sharks impossible. Instead, the decision was made to move the barracuda from Burgers' Zoo. As luck would have it, Blijdorp in Rotterdam was keen to have them. Today's barracuda came from the Copenhagen aquarium as 20–30 cm long fish in 2014. They were easy to transport at the time, but they are now a metre longer. What is the best way to deal with that?
Complications
Barracuda can float perfectly relaxed and motionless in the water, but they can also accelerate like a Ferrari. Barracuda also have very sensitive skin with tiny scales. These two reasons make it quite difficult to catch and transport these long fish without injuring them. The Ocean team discussed several options: 1) catch the fish with a hand net during feeding; 2) place a large standing net in the basin and gradually close them in; 3) catch the fish with a hook and line. Unfortunately, all the above methods carry the risk of major injuries. Draining the 600,000-litre aquarium down to a very small layer presented significant logistical challenges. One interesting option was sedating the animals. A light anaesthetic would allow the barracuda to be moved without too much stress and injury. The first idea was to administer an anaesthetic through the feed, but after consulting several vets in Europe and America, this option proved too risky. After all, how much anaesthetic should you use? And how would the other barracuda react to a half-sedated conspecific? We wanted to anaesthetise them one by one in a small basin, but we needed a way to get them into that small pool.
Training
The plan: hang a two-metre-diameter 'bucket' diagonally in the water and teach the animals to swim into the bucket and eat there. Once they are used to that, we tip the bucket over to catch the animal. An excellent plan—the only thing left was the implementation! We designed and rolled out a training schedule. Within a few months, several barracuda were already used to the new routine. The first animal was caught in the 'bucket', sedated and transported to Blijdorp in a transport tank measuring 2.4 metres in diameter. The capture, sedating and transport procedure was repeated with the other animals.
The 'Little Ocean’ will soon have threadfin trevallies on display. These animals have been living behind the scenes for 1.5 years and are maturing well. You can expect an article on these beautiful fish in a future ZieZoo!
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