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Comment by gepeake | Hacker News Reader

Sonar is a likely cause for whales beaching themselves, using sound to transmit the image data underwater may do more harm than good.

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The authors discuss the impact on wildlife:

> In the Keyser Pod experiment, the cumulative sound exposure level (SELcum) value was 191.29 dB re 1 μPa2s at a distance of 10 meters from the transmitter. Note that this value is within the limits defined by Marine Mammal Protection Act (MMPA) for all marine mammals except for mammals that lie within high-frequency cetacean hearing group. However, there were no mammals from this group (or any other group) within the 10-meter radius of the transmitter.

190 dB ???!? Is that different under water, and how much is left after 10m?

I mean 130-140 dB is the jet engine and the range were exposure without plugs is painful and longer than few seconds causes damage. This is 6 magnitudes higher, how can this be a good idea?

(Sounds like microwave wireless energy transmission: it's great, unless you care for birds which just get roasted if they fly through the beam?!).

Sound pressure readings under water are different than in the air. They're measured at 1µPa instead of 20, and water has a higher impedance.

Most legit scientists agree that loud, low frequency sonar have negative impact. But this is not that. It’s high frequency and low power.

> Sonar is a likely cause for whales beaching themselves

While I join the outrage, evidence of whale beachings predate the development of sonar by some 14K years.

And evidence of bison killings predate bison being nearly killed off. It's more about sonar causing more whales to beach themselves, not that it didn't happen ever in nature, but that our actions cause it to happen way too often. This is a weird argument.

It was not an argument, thus the qualifying first 5 words of my comment. I hate sonar, in anger accept that it beaches whales, but acknowledge that whale beachings predate sonar.

the earth makes all sorts of horrible noises across the spectrum.

I think that it's unfair to use that as a defense of sonar unless you're certain that the number hasn't been trending upwards since the beginning of sonar usage.

if whale navigation is somehow affected by strange very high or very low noises it's not outside the realm of possibility that there have been plenty of whales beached simply due to tectonic/planetary movement inducing confusion.

You're preaching to the choir. I think there should be a century-long moratorium on all commercial, industrial and military activity in the oceans.

It’s a cause. Likewise, people have been dying long before the development of guns.

They likely weren't dying from gunshot wounds.

They were, however, dying from organ failure and blood loss.

Also, some drowned, some burned to death, some fell from a great height, some were trampled, some buried alive. Hardly any were killed by metaphor.

As it happens with us, whales can die by several different reasons.

I wonder if you could use free space optics or mm wave radio (above the absorption spectrum of water) to do this without the environmental externalities. Dispersion is still a problem underwater with these high frequency EM waves, but presumably a researcher could deploy some relays along with the cameras.

Passive sound absorption for power could also work without any sort of active sonar pinging.

There are some videos of divers experiencing sonar underwater on YouTube. Seems like a weird experience.

https://m.youtube.com/watch?v=sCmyZYYR7_s

Does not seem very compatible with monitoring aquaculture systems without damaging the fishes skeleton.

But it looks damn sexy

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