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Killer Whales vs. Great White Sharks: Genetic Proof of Predation! 🦈🐋 · How To Protect The Ocean

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  About a decade ago, great white sharks
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  were popping up in South Africa on
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  beaches without their livers.
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  They were dead and they were just lying
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  there, just carcasses were gone,
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  and people were like, "What
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  is going on with these livers?"
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  Later found out that there were two orcas
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  named Port and Starbird
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  that would come in every once in a while
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  and kill said great whites.
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  And these great whites
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  are known to be massive.
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  They're like 18 footers, 20 footers, and
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  they were typical of that area.
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  That's where air jaws started.
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  They were revered for what they could do,
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  and that's jump out of the water as
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  they're attacking the seal.
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  They were the apex predator of the area
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  until these orcas came by.
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  That fueled a lot of research to find out
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  why these orcas are
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  going after these livers,
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  what's happening, and until recently, we
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  haven't really seen DNA
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  evidence of this happening.
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  We haven't really seen that, hey, these
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  shark bites are from orcas.
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  We haven't really seen these bites on the
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  sharks that are
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  actually from orcas until now.
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  There was a paper that was recently
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  released that was published in Ecology
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  and Evolution, a peer-reviewed journal
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  article that actually says genetic
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  evidence of killer whale predation on
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  white sharks in Australia.
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  Now, I've been talking about South Africa
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  because Port and Starbird, the orcas that
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  have been around that have actually been
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  killing these great white
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  sharks are in South Africa.
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  Now, they actually have
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  DNA evidence in Australia.
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  We're going to talk about why this is so
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  important on this episode of the How to
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  Protect Yours podcast.
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  Let's start the show.
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  [Music]
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  Hey, everybody. Welcome back to another
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  exciting episode of the How
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  to Protect the Ocean podcast.
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  I'm your host, Andrew Loewen, and this is
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  the podcast where you find out what's
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  happening in the ocean, how you can speak
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  up for the ocean, what you can do to live
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  for a better ocean by taking action.
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  On today's episode, we're going to be
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  talking about just eating great whites.
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  I know I've talked about this before, but
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  now we actually have genetic evidence
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  that shows there are some orcas that are
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  eating great whites in Australia, not
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  just South Africa, but in Australia.
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  This is a pretty big deal because we've
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  seen videos of orcas
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  attacking sharks before.
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  We know they're an apex predator.
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  We know they go after other apex
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  predators, but orcas truly are the apex
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  predator of the ocean.
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  They're smart.
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  They hunt together.
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  They're fast.
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  They're enormous.
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  And like I said before, they're smart and
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  they're going to go
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  after these great whites.
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  But we haven't really seen genetic
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  evidence of these great
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  whites actually biting sharks.
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  We know they go after the liver because
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  the liver is so dense in nutrients that
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  there's a reason why they go.
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  Orgas have been known
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  to attack bolamolas.
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  They've been known to attack a lot of
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  different sharks,
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  blue sharks and so forth.
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  But we didn't really know until recently
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  and I mean recently by the past couple
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  decades that orcas start going after gray
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  white sharks or they have been going
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  after gray white sharks.
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  And we've seen it in South Africa.
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  We've seen it in other places, but now
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  we're seeing it in Australia.
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  And so I thought this
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  was pretty interesting.
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  So it was kind of interesting to see the
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  genetic analysis confirmed the presence
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  of orca DNA within a bite room offering
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  direct evidence of
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  predation of these great whites.
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  They also saw some I guess some scavenger
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  sharks that were also had bite marks
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  against the great white sharks.
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  And that was a seven gill shark or a type
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  of seven gill shark, which I
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  thought was pretty interesting.
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  Obviously, these were post death.
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  And so these bites were just as the shark
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  was dying and probably
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  floating or in the water column.
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  They come in and they grab their flesh
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  and they leave as well.
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  So now previous anecdotal reports and
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  indirect observation suggested that orca
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  predation could lead to behavioral
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  changes in white sharks such
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  as avoidance of a specific area.
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  This study provides concrete evidence
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  such that interactions happen and which
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  may also have cascading effects in the
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  marine ecosystems like
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  Australia has some big great whites.
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  We know this.
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  This may or may not be the first
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  predation on a great white.
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  We don't know, but it could lead towards
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  movement of these great
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  whites to different areas.
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  We saw this happen in South Africa.
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  There's still a bit of scientific
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  controversy in that whether it is due to
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  the lack of prey that's in
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  the area for the great whites.
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  So they've actually moved areas or if
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  it's the increase of predation by port
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  and starboard and some South African
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  areas where these great whites are
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  actually just moving away and moving.
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  I think it's more to the
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  east of where they were before.
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  We don't really know for sure, but we do
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  know that they avoid the areas because
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  there's something going on in that area.
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  There is a good reason to believe that,
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  hey, look, if these orcas are coming in
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  and they're predating and they're getting
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  better at doing it in South Africa, it
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  would usually take two
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  orcas to grab the liver.
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  One would actually hold the great white
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  while the other would rip the area where
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  the liver would be and then actually take
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  out the great white without really
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  destroying the animal.
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  I think killing it, but
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  really ripping the animal apart.
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  They'd be very precise bites.
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  Then we heard from Dr.
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  Allison Towner on the Beyond Jaws podcast
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  that she has seen one orca actually take
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  out a number of great
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  whites within a few hours.
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  So that this goes to show they're
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  actually getting better and better at
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  killing these great whites.
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  And so the fact that we see some orca
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  predation on great whites in Australia
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  could mean that these great whites are in
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  trouble from a population
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  standpoint from these orcas.
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  So now this predation event actually
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  raises some interesting questions about
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  the ecological balance
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  between these two predators.
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  It also highlights the importance of
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  understanding predator prey interactions
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  in designing conservation strategies for
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  both species, particularly in regions
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  where human activities and environmental
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  pressures are increasing.
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  So just think about it.
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  If you have a great whites, which we're
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  at one point and endangered species,
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  they're starting to come back because of
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  specific conservation strategies that
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  would allow their prey to flourish.
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  Like in California, we saw an increase in
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  the great white population because there
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  was an increase in
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  the sea lion population.
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  That was because of the
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  Marine Mound Protection Act.
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  Now, there was also an increase in the
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  sea lion population, not only because of
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  the Marine Mound Protection Act, but the
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  Magnuson Stevens Act, which is a
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  fisheries act that allowed for more
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  protection on anchovies and sardines,
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  which the sea lions would eat.
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  So having those policies in place allowed
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  not only the prey of the sea lions to
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  flourish, but allowed the sea lions to
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  flourish, which is the prey to the great
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  whites, which allowed the
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  great whites to flourish.
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  Now there are so many great whites in
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  Southern California.
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  They're starting to move northward or
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  they have moved northward into the San
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  Francisco Bay area in the Monterey area.
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  And now there's like large great white
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  sharks in those areas, adult great white
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  sharks, where the Southern California
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  population are actually
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  juvenile sharks in that area.
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  So it's like a nursery habitat
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  for those great white sharks.
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  This all changes if you have orcas coming
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  in and predating on great whites.
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  It could shift the balance of specific
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  prey of the great whites.
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  So for instance, if there are seals in
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  the area in Australia, what the great
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  whites are eating, the net seal
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  population could grow, which could affect
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  their prey that would actually reduce
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  their prey and the balance
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  would be all shifted off.
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  I don't know if this is happening.
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  This is all assumptions.
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  But this is what could happen when you
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  have orcas come into an area and wreak
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  havoc on an apex predator population.
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  So we're going to see some really
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  interesting research come out in the
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  future from these two apex predators.
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  The significance of the study is this is
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  one of the first studies to provide
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  genetic evidence of orca
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  predation on great white sharks.
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  While previous accounts were based on
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  indirect observations, such as scars on
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  sharks or even changes in their presence,
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  this study is definitely
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  proof of direct interaction.
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  So this is one of the studies
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  that says, hey, you know what?
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  We actually have DNA evidence that orcas
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  have bitten in these areas where they
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  would normally bite in the girdle area
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  where the liver is just behind.
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  Also, these findings contribute to the
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  understanding of predator hierarchy,
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  competition and ecological impacts in
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  marine systems, particularly in regions
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  like South Africa
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  where both species coexist.
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  There's going to be some really cool
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  things that are coming out of Australia
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  from this research, even South Africa, as
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  we really try to understand that
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  relationship between orcas and great
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  whites as well as other
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  sharks that end up flourishing.
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  So, for instance, in South Africa, when
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  we saw the disappearance of great whites
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  in the Gansby area, we also saw an
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  increase in seven gill sharks in that
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  area because seven gill sharks used to be
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  a prey item of these great whites.
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  So it's going to be really interesting to
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  see what comes out further. And I can't
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  wait to see what happens. I hope that the
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  balance exists, but this is
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  nature. This is what happens.
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  Now, previously, I said that this is
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  going to be interesting to see how this
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  plays out, especially with human
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  interactions or even environmental
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  pressures that are increasing.
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  So climate change is increasing. Coastal
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  development is increasing. We're seeing
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  fishing pressures increasing.
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  All these play a dynamic role, not only
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  as individual issues, but also as
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  cumulative issues. And when you manage a
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  population, a lot of populations, fish
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  populations in general, they actually
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  have slowed in their recovery because of
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  outside pressures such as climate change.
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  We don't know how fast a fish population
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  can rebound off a change in population
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  dynamics or predator prey dynamics if
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  there's something else slowing it from
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  actually recovering or
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  actually the same area.
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  The cod population, for instance, in the
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  northeastern or northwestern Atlantic or
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  northeastern Canada, we have seen cod go
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  from so abundantly available that you can
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  just throw a bucket in like the 1800s and
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  you could actually just grab it with a
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  bucket and you'd grab
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  like two or three fish.
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  Now the cash per unit effort is so high,
• 1:09:21
  meaning it's really hard to find cod and
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  there's so much protections on a call
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  that you just can't have a viable
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  commercial fishery like we
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  used to have in the past.
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  But that was because we let fishing get
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  out of hand. We've been wanting that
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  population to recover and we've seen
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  somewhat of a recovery, but it's taken
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  over 30 years for
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  that recovery to happen.
• 1:09:39
  And we're still not seeing it even close
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  to what it used to be in the 70s and 80s
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  where they started to fall down as we
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  started to track those fish stocks.
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  So you just never know what's going to
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  happen. And a lot of times climate
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  change, more fishing pressures for other
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  fish that can affect the marine ecosystem
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  in the communities that these fish are
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  living in, that cod fish are living in.
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  You just never know what's going to
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  happen. So having the data, having more
• 1:10:04
  research, understanding how each of these
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  issues like climate change, fishing,
• 1:10:08
  coastal development, water pollution and
• 1:10:10
  marine plastics, all these different
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  types of human issues that will cause a
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  disturbance individually and
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  accumulatively will play a role in the
• 1:10:17
  recovery or the change in the population
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  dynamics and the predator prey
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  relationship between
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  orcas and gray whites.
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  It's going to be really interesting to
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  see how this happens. But of course, you
• 1:10:27
  can help by reducing your energy
• 1:10:29
  consumption. You can help by reducing
• 1:10:31
  your single use plastic usage. You can
• 1:10:33
  help a lot of ways eating more
• 1:10:35
  sustainable fish or avoiding fish
• 1:10:37
  altogether or seafood altogether.
• 1:10:39
  There are so many ways that you can help
• 1:10:41
  individually. If you want to find out
• 1:10:43
  more, you can find out by staying in
• 1:10:46
  touch with this podcast.
• 1:10:48
  All you have to do is subscribe to the
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  YouTube channel and hit that notification
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  bell so you don't miss
• 1:10:52
  any of the other episodes.
• 1:10:53
  You can also hit me up on Spotify, on
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  Apple Podcasts or your favorite podcast
• 1:10:57
  app. And if you want to get ahold of me
• 1:10:59
  directly, you can DM me on Instagram at
• 1:11:01
  how to protect the ocean. But thank you
• 1:11:03
  so much for joining me on today's episode
• 1:11:05
  of the how to protect the ocean podcast.
• 1:11:07
  I had a great time talking to you today.
• 1:11:09
  I hope you enjoyed listening. Have a
• 1:11:10
  great day. I'm your host, Andrew Lewin.
• 1:11:12
  We'll talk to you next
• 1:11:12
  time and happy conservation.