Smooth circles on the ocean surface

[acheong87]

Hello,

I'm new to surfing (and being past the break in general). I've been noticing circular patches on the water surface where there's no choppiness. At first, I thought it might be jellyfish, but some of these were huge (10 feet in diameter) and besides, others didn't seem to be phased by them.

What are they?

[kitesurfer]

What are they?

A job for Mulder and Scully?

KS

[oldmansurfer]

Is that a reef break? Perhaps it could be a boil where the water comes up from a channel in the reef. Googled boil and found this so I guess it could be rocks to that cause a boil http://encyclopediaofsurfing.com/entries/boil

[jaffa1949]

Whale farts and exhalations, the farts stink like bad fish oil, the exhalation much less so!

Humpback circles

Or more interestingly this link on specialised exhalations



https://www.youtube.com/watch?v=lftSVNjyuLU

[acheong87]

Thanks Jaffa1949 for the lead—I would have never guessed they were caused by whales. However from what I've been reading, it doesn't seem like they're caused by "exhalations". They seem to be more commonly called "fluke prints," i.e. shapes formed by the fluke (a whale's tail) as the whale moves. (But then, I can't explain the smells you've experienced.)

From "Formation of Ocean Surface Patterns by Cetacean Fluke Oscillations, Levy R. and Uminsky D."—

Flukeprints are a visible pattern that appears on the surface of the ocean when a whale is swimming at a shallow depth or beginning a terminal dive. [...] The outer edge of the print is accentuated by small ridges, where wave-breaking may occur. The interior of the print is smooth compared to the surface outside the print, since very few capillary (wind-driven) waves are visible [...] The print grows radially and may remain visible for as long as several minutes, depending on ocean and wind conditions. A popular name for this phenomenon is "whale footprint" [...] While smaller swimming animals such as dolphins and manatees create surface prints, whales create the largest prints with the longest duration. [...] existing theories from fluid mechanics can provide an accurate perspective on this interesting phenomena. The characteristics of the flukeprints can be explained as a result of the hydrodynamic shedding of powerful vortex rings off the edge of the whale's fluke during swimming/diving and the ring's subsequent interaction with the ocean surface. [...] a buoyant object (such as an orange) thrown into a flukeprint consistently moves to the outer edge of the print. This indicates that there is steady movement of water from the center of the print to the edge. [...] The motion of the whale's fluke sheds vortex ring structures that create a powerful jet of fluid, circulated up through the center of the ring. When fluid from the jet contacts the surface, an outward radial surface current induces a breakwater. This in turn damps the wind-driven capillary waves in the center of the print and causes the wavebreaking observed at its edge.

Anyway, I'll now feel okay when one of these things creep up toward me—I've been swimming away all this time, just in case.

[acheong87]

Ah, turns out we're both right, Jaffa1949. Whales also blow bubble rings—apparently sometimes to round up masses of prey by trapping fish toward the surface.



And here are the fluke prints a.k.a. "whale footprints" I had been seeing:



A page with more information: http://www.cape-cod-insider.com/cape-cod-whale-watching.html.

[jaffa1949]

Did you follow the the link to the Toroidal bubbles.
Humpbacks also do a group technique called bubble netting where they surround and tighten a net of bubble around small fish they wish to eat the bubble keep the fish corraled and the whale take turns in scooping them up!
https://www.youtube.com/watch?v=z00G0RxeSP0

They were in fact fluke circles, whale farts often have a very smelly oil slick.

[oldmansurfer]

There are no whales in the lineup, it's too shallow for them.

[jaffa1949]

There are no whales in the lineup, it's too shallow for them.

Not so here, Southern Right Whales use the sand bars of our line to sand off barnacle right beside where we are surfing, this has been the same group over the last five years.
I shoot them each August and September.

There is no steep drop off here they are all sand bars, and we have a big continental shelf

[oldmansurfer]

Well they are right at the surface so won't be making any smooth circles in the water for any reason or if they did you would easily see it was them doing it so not what the original poster was wondering about

[jaffa1949]

The circles I posted were by the the sames whales yes the water was deeper!
The fart part has happened right next to me when I have been surfing, oil slick and great fish stench slippery enough to grease the board!
The fart part was also underwater at the time, not inverted at all .

[oldmansurfer]

Yeah but you knew it was a whale and didn't need to ask anyone about it

[jaffa1949]

I didn't ask the question in the first place, just giving answers

[benjl]

That is fascinating!! Thank god there are no whale farts around where I surf hahaha although perhaps the grease would line the board and make it run faster?

[oldmansurfer]

So if he saw whales around maybe it was whale farts but I am guessing that he didn't see any and it was the very common thing we see all the time and call it boils. I can just hear him telling the other surfers "Jaffa says they are whale farts"

[jaffa1949]

I know boils and I know tail fluke circles and I nose whale farts
One of my reef breaks the boil indicates the take off spot the outer boil means if you are not at least as far out as it , you are about to get a severe set on the head.

[oldmansurfer]

By the way I am jealous of you seeing whale farts. I work as a volunteer on a marine mammal stranding group here on Kauai. Never seen (or smelled) a whale fart LOL (now dead whales I have smelled a few.)