The white beluga whale, suspected to be a Russian “spy whale,” has died in Norway.

The beluga known as “Hvaldimir” was first discovered in 2019 by a group of Norwegian fishermen about 290 kilometers off the Russian maritime border after swimming to the group’s boat wearing a harness attached to a small camera with the words “Equipment St. Petersburg” written on the front in English.

This discovery led to the belief that the whale was a Russian spy – although the Russian Navy denied these claims at the time, saying in a statement to a Russian broadcaster in 2019: “We have military dolphins for combat missions, we do not cover that up,” BBC News reported.

“If we were to use this animal for espionage, do you really think we would attach a mobile phone number with the message ‘Please call this number’?” the Russian Navy reportedly added.

In an Instagram post on Saturday, August 31, the NGO Marine Mind wrote a tribute to Hvaldimer and announced his death.

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“*In loving memory of Hvaldimir* It is with heavy hearts that we share the news of Hvaldimir’s passing,” the caption reads. “This morning, after receiving a sighting report from a local, our team arrived to find Hvaldimir floating peacefully in the water. It is not immediately clear what caused his death, an autopsy will be performed to determine his untimely death.”

“Over the past five years, he has touched the lives of tens of thousands and brought people together in awe of the wonders of nature,” they continued alongside photos of the whale. “His presence taught us the importance of protecting the oceans, and in doing so, he also taught us more about ourselves.”

The NGO added: “Hvaldimir bridged the gap between humans and wild animals in a way that few can. He was special to so many and left a lasting mark on all who had the privilege of meeting him.”

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“Rest in peace, Hvaldimir. We will miss you very much, but never forget you. 🌊💙,” they said, before concluding with the hashtags “#Hvaldimir #MarineMind #OceanConservation #BelugaWhale #InMemory.”

In a statement to PEOPLE, the Norwegian Fisheries Agency said Hvaldimir was found in the port of Stavanger in southwestern Norway. According to NBC News, the 14-foot-long, 2,700-pound whale had been living in the area since 2023.

“Due to the great attention the whale attracted, the Directorate of Fisheries has decided to have an autopsy performed to determine the cause of death,” the Norwegian Directorate of Fisheries added. “The autopsy will be performed by the Norwegian Veterinary Institute and the result will be published in two or three weeks.”