Incursion in the Stockholm archipelago

In the early 80s the Swedish navy detected strange sounds in their territory and they didn't know what could be making them. Why were they so persistent? And why were there bubbles reported in the areas near the sounds?

References
- Most of the story from
https://www.rbth.com/science-and-tech/326583-stinky-mystery-russia-sweden
- http://www.maritimeherald.com/2019/how-fish-farts-almost-caused-a-diplomat
ic-accident-but-founded-the-most-liberal-city-in-the-world/
- The Canadian paper:
https://web.archive.org/web/20050515132711/http://www.zoology.ubc.ca/%7E
bwilson/herring/FRTing_herring_Wilson_et_al.pdf
- The Swedish paper:
https://www.sciencedirect.com/science/article/abs/pii/S0990744003000172?vi
a%3Dihub
- https://www.improbable.com/2012/02/29/fish-farts-russian-submarines-the-sw
edish-foreign-minister/

Transcript

1. Incursion in the Stockholm archipelago Björn Andersson
2. In the 80s the navy recorded strange sounds in the Stockholm archipelago
3. With the recording there were often reports of bubbles
4. What could be making these sounds?
6. This was during the cold war. The soviets could be in Swedish water
7. The Soviet Union denied everything
8. Of course they did. But, they were not believed
9. Because ‘81 they “accidentally” ended up on an island in the archipelago
10. But, Sweden wasn’t able to find the submarines they expected in their waters
11. And it continued even after the collapse of the Soviet Union
12. ‘94 the Swedish prime minister Carl Bildt was fed up. He sent an angry letter to Boris Yeltsin asking him why he couldn’t control his navy
13. Then in ‘96 something happened…
14. A scientist was invited to explore the strange sounds that had been evading the navy since the 80s
15. He was surprised at the sounds, it sounded like someone frying bacon. Not like a propeller or any pinging, which is what he’d expect
16. And on top of that, why were there small bubbles in the area of the sound?
17. Herring (Clupea harengus)
18. “The swim bladder is connected to the alimentary canal and the anal opening”
19. “Gas release from the anal opening is often observed when the fish is scared or during ascent and descent”
20. The fish farts.
21. A large school of herring farts loud enough to be picked up by navy sensors
22. The scientists involved in this won an IgNobel price for biology in 2004 for their paper “Sounds produced by herring bubble release”
23. And even better, another Canadian team had made similar findings, and they shared their IgNobel price
24. Their finding is that they’re not 100% certain, but they believe herring communicate by farts
25. How herring farts almost lead to a diplomatic crisis: Magnus Wahlberg at TEDxGöteborg
26. References - Most of the story from https://www.rbth.com/science-and-tech/326583-stinky-mystery-russia-sweden - http://www.maritimeherald.com/2019/how-fish-farts-almost-caused-a-diplomat ic-accident-but-founded-the-most-liberal-city-in-the-world/ - The Canadian paper: https://web.archive.org/web/20050515132711/http://www.zoology.ubc.ca/%7E bwilson/herring/FRTing_herring_Wilson_et_al.pdf - The Swedish paper: https://www.sciencedirect.com/science/article/abs/pii/S0990744003000172?vi a%3Dihub - https://www.improbable.com/2012/02/29/fish-farts-russian-submarines-the-sw edish-foreign-minister/