Animation of a blue whale trying to avoid ships • Hacker News Board

Re: Animation of a blue whale trying to avoid ships

#91

Post by kortilla » Mon, Feb 15, 2021, 6:26 AM UTC

runarberg wrote: post #83

kortilla wrote: post #81

Earlier quoted context omitted.

> Boats, especially the larger ones you see being used for fishing/shipping generate a lot of noise due to powerful engines and underwater cavitation caused by their propeller spinning. A couple of things. First, that video shows you how relatively quiet the ships are unless you are right underneath the back. You can’t even hear the engine noise towards the front of the ship (which is likely why a ship the size of a…

Sound travels differently underwater. A diver senses every sound as if the source is from their own head and all sound sort of blends into one. A whale has a much easier time distinguishing different auditory signals underwater then a diver does. Furthermore, a whale can probably sense the direction the sound comes from and how fast it is moving. A diver failing to notice a giant ship is no evidence that a whale will…

The video was meant to show how loud ships were. It did not.

Re: Animation of a blue whale trying to avoid ships

#92

Post by dredmorbius » Tue, Feb 16, 2021, 7:03 PM UTC

advisedwang wrote: post #46

matt-attack wrote: post #45

I think to properly interpret this, you’d need to see a control case where the same whale is the same or similar area with zero ships. Do they normally just swim in that pattern? Perhaps that’s the normal manner in which they troll for krill.

Sadly I don't think we can get that control case without shutting down all shipping in a huge area.

Shipping traffic is surprisingly concentrated into high-traffic sea lanes. Ships (like aircraft) follow least-energy, shortest-distance paths between economical (high-traffic) ports.

The Southern Ocean in particular sees exceptionally little shipping traffic.

Re: Animation of a blue whale trying to avoid ships

#93

Post by scubazealous » Tue, Feb 16, 2021, 7:51 PM UTC

kortilla wrote: post #81

scubazealous wrote: post #55

Earlier quoted context omitted.

Disclaimer: Not a marine biologist by trade but took several classes and have close friends in the profession. What people do not realize is that these whales communicate by sound and have very sensitive hearing. Boats, especially the larger ones you see being used for fishing/shipping generate a lot of noise due to powerful engines and underwater cavitation caused by their propeller spinning. This can drown out whal…

> Boats, especially the larger ones you see being used for fishing/shipping generate a lot of noise due to powerful engines and underwater cavitation caused by their propeller spinning. A couple of things. First, that video shows you how relatively quiet the ships are unless you are right underneath the back. You can’t even hear the engine noise towards the front of the ship (which is likely why a ship the size of a…

That diver did not have the ship sneak up on him, he was diving in a shipping channel and knew there would be a ship coming up. He prepared by staying next to the large chain on the bottom and holding onto it so he would not be sucked into the propeller. In addition, the reason the ship did not sound "loud" to you is the way gopro records audio. Had this been recorded with a calibrated hydrophone the noise would have been off the charts.

I agree with you the bigger problem is sonar but I hold my opinion the whale in the video swims how it does because it is avoiding the sound of these ships, it is not acting on sight or attracted to wakes/ plankton.