New underwater device tested to count king crabs in Barents Sea

A self-propelled underwater vehicle called Triton was used in Norway’s Porsanger Fjord to count the number of king crabs in the area, the Norwegian Institute of Marine Research reports on its website. Getting an accurate count will be crucial later this year when the Norwegian government sets annual quotas for fishermen.

So far, Norwegian researchers have mainly used the traditional method, which involves sailing the waters of the Barents Sea on a large research vessel and lowering a video camera to the seabed. The researchers sit in the control room and count the crustaceans by hand. They then bring up some of the crabs to examine them.

As the Norwegian Institute of Marine Research reports, Triton, which takes three photos per second, has advantages:

“We don’t need to collect all the crabs anymore, although we will still need to catch some to get information about sex and other things,” said marine scientist Cecilie Broms. “Triton is taking pictures of the crabs as they live on the bottom, which will give us a better understanding of their distribution. Plus, we know exactly how big the area is covered by the cameras and can improve calculations of how many crabs are in the area.”

The device is designed to reduce the cost and carbon footprint of crab counting in the future, the institute reports. While a research vessel monitors crabs in one area, the sonar-equipped device could do the same thing a little further out, greatly expanding the crab-counting area.

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“And then the goal is for autonomous ships to go more and more by themselves,” explains Cecilie Broms, “By using sonar, we can also now cover a larger area on the bottom,” adds Broms.

The king crab is native to the Pacific Ocean and was introduced to the waters of the Barents Sea in the Soviet Union, in the Russian Arctic. The invasive species has since spread to the Barents Sea in Norway, and a multi-million dollar industry has developed around it.