Modern sharks attacking whale newborns/calves?

[prehistorican]

I saw an article about great whites attacking right whale calves. I usually thought whales were way out of the league of modern sharks, even small ones, but this seems interesting. If the great whites really are confirmed to kill these calves then it would be evidence of great whites attacking similar sized animals (along with false killer whales). They wait for the mother to birth the whale, and in the following moments where the mother cannot defend the calf due to pain and weakening from recent birthing, the shark attacks the calf.
Link: yalikedags.southernfriedscience.com/great-white-sharks-attack-whales-seriously/
Similar Article: rightwhales.neaq.org/2012/04/new-publication-sharks-predate-on.html


I found this interesting article about 10-20 dusky sharks most likely killing a newborn/calf humpback whale by ganging up on it and causing exhaustion to set in, drowning the whale. This really intrigued me and reminded me of the 29 or 30 transient orcas attacking the 60 foot blue whale, however this shark attack is more like a feeding frenzy. The orca superpod body weight to prey ratio should be around 9:2. The group of attacking dusky sharks body weight to prey weight ratio is should be around 3:1 (howver the whale was an inexperienced calf I guess so..?). I thought this was unusual considering the gracile jaws of this species compared to larger sharks.
Link:https://www.newscientist.com/article/dn28677-sharks-seen-hunting-and-killing-a-whale-for-the-first-time/

What do you think?

[creature386]

I was personally more surprised by the sheer number of sharks behaving akin to an orca pack (though they most likely did not cooperate) than by the kill itself.

[prehistorican]

I would think that the sharks emitted something akin to the "Yummy Hum" which is a low frequency sound that great whites make to alert other members of its species to a possible food source. There are a few examples of sharks cooperating, but usually they are smaller species. There was another report of great whites pushing a whale carcass to deeper water to feed on it more easily. Here is what one article states
"Getting Along
There are three species of shark that have been conclusively observed hunting in groups. The broadnose sevengill shark, the sand tiger shark, and the blacktip reef shark. All three of these species use similar methods of cooperative hunting when working together.

The broadnose sevengill shark is a large species that typically lives a solitary life. However, when these sharks attempt to prey upon a more dangerous animal, such as a cape fur seal, they gather in large groups. The large school of sharks surrounds the seal, preventing it from escaping. Then the school slowly begins to tighten the circle, pressing in on the seal from all sides.

Eventually one of the sharks runs in for a bite, usually from behind when the seal isn’t looking. From there the rest of the sharks begin to run in and take bites at the seal one by one until the seal becomes too weak to defend itself, at which point the sharks descend upon and devour it.

Sand tiger sharks and blacktip reef sharks use a similar method when they hunt in groups. A few sharks will swim along the outskirts of a large school of fish. The sharks will then herd the school of fish up against either the shore or some structure and block off their escape. From there the sharks take turns rushing into the school and attempting to catch some fish, while the other sharks continue to prevent the school of fish from escaping"

It seems that a few sharks species attack in groups like orcas but they usually only do it during hunts and have little social bonds with each other.

[elosha11]

^Yes, I've seen this article re predation on right whale calves before and referenced it. As a matter of caution, I would note to you that we don't know for sure which species of shark has attacked fkw, only that there are bite marks indicating some species of large sharks have attacked them. So the false killer whale attacks may or may not be from great whites.

[prehistorican]

Also, I swear I found an article about an adult great white shark killing a sick bull orca. I well remember some of it, it was I think from the 1900's. There were some black and white photos, not really sure but I remember the shark disembowled the weakened orca in a single bite, killing it almost instantly. I can't seem to find it though, what a damn shame.

[prehistorican]

Alright guys quick update on the subject. It seems there were only about 10-20 dusky sharks involved around 2-3m in length, from this we can assume a weight of around 150-170kgs average for each shark compared to a 907kgs humpback whale.
Here is the research paper on the subject:
www.researchgate.net/publication/276500821_First_observations_of_dusky_sharks_Carcharhinus_obscurus_attacking_a_humpback_whale_Megaptera_novaeangliae_calf
The sharks did not mortally wound the whale, but rather the exhaustion from the chase and weakening from multiple lacerations and injuries prevented the whale from surfacing causing it to drown. The sharks bit down through the skin and blubber, only damaging small amounts of tissue or muscle. I still find this quite amazing considering “The diet of this shark includes small schooling fish such as sardines and anchovies, as well as larger fish like tuna, mackerel, flatfish and eels. The dusky shark also eats dogfish, catsharks, skates and rays”. This shark is a FISH eater with gracile jaws, not built for taking on large mammalian prey (although occasionally consuming normal or small sized ones). If you consider the predator to prey weight (usually shows efficiency in pack hunting) of this account and the 30 orcas account which resulted in the prey death, then this is quite interesting indeed. Assuming about 4-5 tonnes average for each whale (figure is low to account for juveniles and calves) at about 30 orcas, compared to about 30 tonnes for the 18.2m blue whale the ratio is about either 4:1 or 5:1. The predator prey ratio in this dusky shark account would be around 5:2 or 4:1. (I would suspect 3:1 is a more accurate representation). However the orcas mortally wounded the whale while the sharks exhausted the whale, so I guess maybe they are of equal efficiency.

[elosha11]

Jun 8, 2018 8:18:32 GMT 5 prehistorican said:

Also, I swear I found an article about an adult great white shark killing a sick bull orca. I well remember some of it, it was I think from the 1900's. There were some black and white photos, not really sure but I remember the shark disembowled the weakened orca in a single bite, killing it almost instantly. I can't seem to find it though, what a damn shame.

You actually saw a source for this? I've heard Grey mention this same event, and Sam1 mentioned recently that he'd heard of a great white attacking an orca, but I've never have found any corroboration for any of this.

I'd be skeptical that even a very large great white could kill a bull orca (even a sick one) in one bite given the significant size difference between the two animals. Unless the orca was close to death from sickness and the one bite was what finished it off. Anyway, did you find this article online or was it some print article? I would think such an unusual event would at some point have generated some attention and more widespread publication.

[prehistorican]

Yes I do remember seeing this, it was an online version of a print article or maybe even newspaper, though I am not sure. It stated somewhere in the article I think that it went for the abdomen, and with a single bite disembowled it. Although for the size, I heard it was around 6m long, and also the white shark was stalking the sick/injured bull orca before making the kill. It was in the past however, around the maybe mid 1900's so many people wouldn't have really cared about this.

[elosha11]

The shark or the orca was 6 meters long? If it's online somewhere, it must be an obscure source. Do you know where the incident took place? Orcas and great whites overlap in quite a few locations.

[prehistorican]

I think it was the coast of Australia? Orca was 6 meters, so probably around 3-4 tonnes in weight. I don't remember the size of the white shark unfortunatley, but there was some sort of black and white picture going along with it, but who knows?