Marine researchers have pulled the first deep-sea fish from a depth of 6.5 kilometers off the coast of Australia. They caught the two as yet unnamed species of the disc-belly family (liberida) with the help of deep-sea scientific measuring instruments worth around €100,000 – and a lobster trap from a local fishing shop worth €28.
Bait at a depth of more than 6000 meters
This was the second expedition of scientists from the University of Mindero’s Deep Sea Research Center in Western Australia (UWA). The aim of the research is to augment the map and index of the undiscovered Indian Ocean. That’s why they headed to the Diamantina rift zone (literally, the Diamantina rift zone) in the southeastern Indian Ocean, which can reach depths of up to 7,100 meters. For comparison: the deepest point on Earth to date is in the Mariana Trench in the Pacific Ocean at a depth of 11,000 meters.
It took the researchers just 2.5 hours to lower their equipment to 6,500 meters as the two deep-sea fish were caught. The measuring probe was placed on the sea floor at this depth and measured the oxygen and salinity values for eight hours. The camera also recorded deep-sea fish attracted by the attached bait.
Deep sea fish melts after a short time on board
The length of the fish caught by the camera and the trap was between 10 and 25 cm. There is no skin or scales for the bodies of two unnamed deep-sea fish brought to the surface, but rather a translucent, jelly-like body.
Deep Sea Research Center founder and University of Western Australia professor Alan Jamieson describes how he and his team had little time to work with the animal. Because at a temperature of 25 degrees Celsius on the surface, the fish began to thaw. “While the fish is in the trap, it’s basically cooked because it hasn’t been anywhere at 25 degrees Celsius for the last 10 million years,” he says. “Once they’re on board, you may have less than 20 minutes to keep them. You can’t leave (the fish) on your desk and take pictures forever because it literally starts to fall apart in front of your eyes because of the temperature.”
Further, Jamison sheds traditional notions: “It’s kind of weird little things. They aren’t what you imagine. A lot of people think a deep sea fish is a crazy big thing, with bioluminescence, big teeth and all of that… Deep sea fish tend to be a bit crazy. Seas to be a little bigger and look a little sad.”
It will likely take a few more years to adequately identify these samples. But there are actually two similar fish from other expeditions in Jamison’s Refrigerator.
Technological advances enable greater visibility
For those exploring the Indian Ocean, Pirate-bellied offers yet another clue to understanding the unique ecosystem of the deep sea. According to Jamieson, very little of Australia’s oceans has been explored below 500 metres. However, technical advances in the past few decades have been crucial to diving deeper and faster into the deep sea. “Ten or 15 years ago we would go out and expose the camera twice. It was considered a huge success, but now we do up to 20 weeks,” Jamison reports.
The next campaign takes the team to Japan. There they want to try to determine the age of deep-sea fish by searching for particles linked to the Fukushima nuclear disaster.
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