Gaping GWS - Video!

This Shark is spy hopping - but it sure looks like RAG is not at all rare in SA!

Watch.

And I cite.

Repetitive Aerial Gaping: A Thwart-Induced Behavior in White Sharks 
WESLEY R. STRONG JR., in Great White Sharks, 1996

Causation

Baits pulled away travelled horizontally, just beneath the surface until they came against the hull at which point the sharks generally turned away. In the vertical baiting configuration, however, the bait could be hoisted directly out of the water as a shark tried to seize it, moving it out of reach more quickly than a bait drawn horizontally. This distinction is important, because 11 of 15 (73%) RAG occurrences were elicited while using the vertical baiting technique, but the technique itself was employed less than 5% of the time.

In each case, RAG followed a series of failed attempts to seize a bait and was immediately preceded by an open-mouthed lunge and miss as a bait was withdrawn. Lack of contact with prey after the feeding MAP was initiated appears to play a role in triggering RAG, but does not solely explain its onset. One factor common to each observation of RAG was that a portion of the anterior buccal cavity was exposed to air before (i.e., during the surface lunge) and during its execution. While failure to obtain food while submerged may eventually evoke a similar response, we never observed an underwater bout of RAG during more than 135 hours of underwater observation. Thus, it appears that contact with air is required to initiate the response.

Now you know - also described e.g. herein, and here.

Story here.

You're welcome!