August 30, 2023 • 41 mins
Are sharks the cunning man-eating villains that we think they are? Or, are they simply carrying out their natural role as the ocean's apex predators?
Listen on to fall in love with these "majestic prehistoric creatures", as our guest and shark expert Alessandro De Maddalena describes them, and gain a new perspective on sharks.
Subscribe to the podcast: https://podcasts.apple.com/au/podcast/roadshow-and-tell/id1666756225
Follow us on Instagram to see photos of stuff mentioned in this episode: @roadshowandtellpodcast
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Kate (00:17):
Welcome to Roadshow and Tell, a podcast for people
hoping to improve their pubtrivia team score.
I'm your host, Kate, and I'llvisit museums so you can learn
things you never knew you wantedto.
In this episode, we visit theShark Museum in Simon's Town,
South Africa.
(00:37):
Simon's Town is just a 40 minutedrive from Cape Town City
Center, and is a gateway to theMarine Big Five, that is whales,
sharks, penguins, seals, anddolphins.
The Shark Museum is a passionproject of biologist and Shark
expert Alessandro de Maddalena.
It's a tiny but picturesque roomthat overlooks the crystal clear
(00:58):
blue waters and quaint buildingsof Simon's Town.
It's filled with so much Sharkparaphernalia and is also used
primarily as a space to hostlectures about all things
sharks.
And the best thing about talkingwith an Italian Shark expert?
The delightful way he describessharks:
Alessandro (01:16):
hammerhead sharks,, Cow Shark, Blue Shark, Mako
Sharks the common thresherShark, the sandbar Shark, the
Southern African Frilled Shark,the Piked dogfish.
The Pygmy Shark and the Thornylanternshark
Kate (01:30):
So listen on to hear about how cage diving can support
Shark conservation, why Jawstaught us poorly about great
whites, and why we should all beconcerned about decreasing
populations of those chompy boysin our waters.
Alessandro (01:46):
My name is Alessandro De Maddalena.
I've been working on sharks formany years.
I'm now 52, and I started to beinterested in sharks when I was
still a kid about seven, eightyears old.
And then I decided I want tostudy the sharks and more
specifically, great white.
I did my studies in naturalscience at the university in
(02:08):
Milan.
I took my master degree and thenI started to do work about the
presence of the great white inthe Mediterranean Sea.
And I built a very big database,about 600 cases of great whites
recorded, both in historical andpresent day.
And from there I started topublish scientific papers about
(02:31):
the biology of the great whitesin the Mediterranean.
Then I extended to other speciesin the same area, like
hammerhead sharks, Cow Shark,Blue Shark, Mako Sharks.
And in 2010 I started to workwith a cage dive operator here
in Simon's Town, South Africa.
So I started to work with ChrisFallows and his wife Monique of
(02:54):
Apex Shark Expeditions.
And then I started to host GreatWhite Expedition with Shark
biology courses.
In the beginning was like okay,I want to try to do this, but it
went so well become a very bigpart of my life and my work.
So I moved here in Simon's Townin 2012 with my family, which
(03:17):
means 10 years ago.
I continue to work articles andbooks about sharks also taking
photos, drawing illustrations,everything about sharks, giving
lectures.
Also started to work inAustralia hosting similar Great
White Shark expedition withRodney Fox Shark expedition, so
the Neptune Islands SouthAustralia.
(03:38):
And later also started to hostorca expedition or killer whale
expeditions in Norway.
And one year ago we opened thistiny Shark museum in Simon's
Town.
Kate (03:50):
Wow.
So what would seven year oldAlessandro who wants to learn
about sharks say to your 52 yearold self now?
Alessandro (03:57):
Yeah.
You know, that for me, thestrangest thing is that when I
was seven, eight years old, Iwatched my very first
documentary, the television, youknow, at the time there was no
internet.
Otherwise, there were only acouple of television channels in
Italy.
So you didn't get many Sharkdocumentaries or none at all?
Kate (04:17):
Not like now.
Alessandro (04:18):
Yeah.
You see very different.
So I watched my very first Greatwhite documentary when I was
that age and uh, it wasdocumentary filmed with Rodney
Fox in South Australia, and nowI'm 52 and I'm working for that
man.
You know, life is so strange andfull of surprise.
Kate (04:36):
So how did the Shark Museum come to be?
Obviously your expeditions weregoing really well.
Why did you start the SharkMuseum?
Alessandro (04:43):
Again, it's a dream of my childhood.
When I was a kid I used to buildtiny models of a shark museum
and that was a kind of an ideastuck in my mind.
What happened is that a coupleyears ago now, we had the, the
chance buying the property.
And this place was a special oneto me because that was actually
(05:06):
part of a b'n'b where I used tostay during my very first great
white expedition in 2010.
So when they put it on sale, Ifelt like, okay, maybe that's
the right time in the rightplace.
We renovated the place and didsome major work and then one
year ago we were able to openthis tiny museum.
(05:29):
I mean, it's very, very small,but still this is something
important to me.
That's uh, the place I wanted tohave to be able to do my
education activities mostly.
Kate (05:40):
So you're mostly interested in great whites.
Why do you think you're mostinterested in the scariest
Shark?
Alessandro (05:45):
Yeah.
Everybody are very interested ingreat whites because they're the
most dangerous species ofsharks.
Still not as dangerous as manypeople think, but it is true.
It's the most dangerous speciesof Shark.
We cannot deny it.
And lot of people actually gotinterested in sharks because of
the movie Jaws.
(06:06):
This is not what happened to mebecause I actually watched Jaws
when I was a teenager, so mypassion started before with
documentaries and books.
Only later I had the chance ofwatching that kind of movies.
Anyway, the main reason why I'minterested in great whites is
just because they are veryprehistoric.
They look like prehistoricanimals.
(06:27):
You can be in the water with anyspecies of Shark.
The smallest one, the biggestone, and all of them are so
beautiful.
But the great white looks mostlike a very ancient, prehistoric
animal.
When I was a kid, I wanted to bea paleontologist.
I want to study dinosaurs, butyou know, I was reading these
(06:49):
books about dinosaurs.
They're all dead.
You know, there is no chanceyou, one day you are going to
see one a live dinosaur like inJurassic Park.
So when I saw my first greatwhite on the screen, I talk,
okay, this one looks like aprehistoric animal, but he's
still alive.
As I say, those species ofsharks are beautiful, but a
(07:09):
great white is just moremajestic and more ancient the
way it looks I mean.
Kate (07:15):
Okay.
I don't know about calling GreatWhites majestic, but they're
definitely funny lookingcreatures.
you might remember Alessandrosaid he studied sharks in the
Mediterranean.
Alessandro (07:26):
Yeah.
You know that, still today, mostpeople living on the
Mediterranean coast don't knowabout the presence.
The And the reason is verysimple.
There used to be a very strongpopulation in Mediterranean,
like centuries ago.
And then about one century ago,the population in Mediterranean
started to decline.
(07:46):
So now there are very, very fewgreat whites left in the
Mediterranean.
So every time there will be onegreat white spotted, a lot of
media will report the news, likeyou know, it's kind of the, the
first time a great white spot.
That's not true.
that's totally wrong.
Actually, the Mediterranean wasthe very first place where the
(08:09):
species, the great white wasfirst described.
Kate (08:12):
That's right.
The earliest recorded Sharkattack ever happened in the
Mediterranean.
It's all thanks to a vasediscovered in Naples dating back
to 725 bc.
Alessandro (08:22):
So they always been there.
They always reproduce there.
They always fed there.
It is simply that like it ishappening in so many parts of
the world nowadays.
The Mediterranean started beforethe humans started to kill them
and to reduce their population.
Now there's just a tinypercentage of what the
(08:44):
population used to be before.
That's why people inMediterranean countries are not
aware of the great whitepresence because it is so rare
to see them, you know?
Kate (08:54):
Speaking of that, can you tell us about what's happening
with this Shark populations inFalse Bay and Mossel Bay?
For reference, False Bay andMossel Bay are two bays in Cape
town, which are known to beparticularly sharky
Alessandro (09:07):
Yeah, let's say that what's happening here, it's just
the same happened before inMediterranean.
I always underline this aspectbecause people usually tend to
be very slow in learning.
We do a lot of damage to naturearound the world.
So we must take an example ofwhat happen in other countries,
(09:29):
to not repeat the same mistakes,but you see it is not happening.
So we have some areas of theworld where the population of
great whites are properlymanaged, but not many.
In most cases, people are justfishing everything and not
caring about these animals.
And then in many countries,great whites or other species
(09:49):
are protected on paper, but thenthere is no enforcement or very
little enforcement.
No control.
And then you know, everybody gothere and fish the sharks, fish
for their prey, kill them onpurpose, or kill them as
bycatch, meaning trying to catchother species of fishes, and
then by mistake, I kill a greatwhite.
(10:10):
You know, that's bycatchhappening everywhere around the
world.
It is very sad because you canprotect as many species as you
want.
But if it's not a properprotection, it is just written
on paper, it is useless.
And now what we are witnessingis that everywhere the number of
(10:31):
species that are protected isbecoming longer and longer, but
enforcement is not increasing.
So you understand it's verydifficult to actually protect
all those species if there isvery little enforcement.
So what's happening here inFalse Bay, Mossel Bay, and let's
say all the waters in theWestern Cape is just the same.
(10:53):
South Africa's been the veryfirst country in world to
protect the white in 1991.
So it's something like anhistorical record, something to
be proud of for South Africanpeople.
The problem is that in thebeginning it worked pretty well
because if you teach people thatanimals can also be use useful
to bring more riches to thecountry more I mean more funds
(11:18):
to the country, more tourism,it's good for the shops, for
hotels, for the restaurant, notonly for the cage diving
industry or the diving industryfor everybody.
So if you properly useecotourism, that's very powerful
tool to teach the entirecommunity, not only people
working with wild animals, thatthese animals are much more
(11:42):
worth when they're alive thanwhen they're dead.
This has been done in so manycountries.
Just think, for example, theMaldives.
All species of Shark areprotected because they make so
much money with the divingindustry.
People dive and travel all overthe world from any country to go
to the Maldives specifically todive with sharks.
(12:05):
If this population are wipedout, then you lose all this kind
of tourists.
The same thing working very wellwith great whites in South
Africa, so people were coming toFalse Bay, Gansbaii, Mossel Bay
specifically to cage dive withgreat whites.
And this if properly regulated,is a wonderful activity.
If it's not properly regulatedmay be a problem for the Shark
(12:29):
and the public, you know?
Then what happen in the recentyears, we saw the number of
sharks decreasing continuouslywell before those two orcas
arrived on the spot.
Kate (12:41):
so, like I said, False Bay has earned a reputation as a
very sharky area.
However, a phenomenon has beenobserved in recent times that
there is an apparent decrease inShark numbers associated with
the presence of two orcas,affectionately known as port and
starboard.
The two orcas are said to beresponsible for at least seven
(13:03):
great white deaths since 2015.
While pods of orcas have beenvisiting False Bay for years,
they've never hunted sharks.
Some scientists hypothesizedthat the sharks are being scared
away from False Bay by thisbehavior, explaining the decline
in sightings.
Alessandro (13:19):
Now a lot of people, a lot of media are blaming two
orcas for the disappearance ofgreat whites in the area.
It's not like that.
The orcas chase the Shark, killa couple of them per year, which
is nothing for a population thatis estimated to be of several
hundreds, but sometimes theychase them away.
(13:39):
But the sharks, if they're stillthere, if they're still alive,
they come back.
You know, if this is nothappening, just because the
number of sharks started todecrease well before the orcas
arrived.
So you understand the decreaseof sharks is because of fishing,
not because of the orcas.
Kate (14:00):
Because there's not enough fish in the Bay for them to
Alessandro (14:03):
fish there.
There is too much fishing in theentire area, even in offshore
waters.
So what happens?
Too much fishing kill sharkssometimes.
So you see that is not onlybecause sharks are culled.
By poachers or by bycatch, youknow?
But also because if we killtheir food, they're going to
(14:26):
disappear or to move to otherareas where there is more food,
you know?
But there must be other areaswhere there is more food.
Otherwise they cannot survive.
Kate (14:37):
And what happens if we wipe out sharks?
I know a lot of people proculling sharks.
What would happen if we wipedout that top apex predator from
our oceans?
Alessandro (14:46):
You know, there are many affects that is very
difficult to predict.
So what happens is that you wipeout the population of an apex
predator.
What's happening, the apexpredator is called apex predator
because is at the top of animaginary pyramid.
In this pyramid you have at thebottom, you have the creatures,
(15:09):
the organism, they do thephotosynthesis.
So we have the phytoplanktonbasically in the ocean.
Then we have the zooplankton,they feed on the phytoplankton.
The producers, thephytoplankton, clearly by
photosynthesis, they create theenergy.
They synthesize the glucose,which is used by all the other
levels.
So it's used by the zooplankton,it's used by sardines,
(15:34):
anchovies, small fish.
And then you go up, you findbigger fishes like snoeks, like
barracudas, like tuna, and thenlike swordfish, you go towards
the top of the pyramid and theamount of fish, the amount of
individuals decrease and theirsize getting bigger.
Kate (15:53):
So at the top of the pyramid is you guessed it, those
big chompy boys.
The actual species of the apexpredators will depend on your
location.
In tropical waters, it could bethe tiger sharks or great
hammerheads.
In South Africa, it's probablygreat Whites or in Norway or
Antarctica, it's probably orcas.
Alessandro (16:12):
But I mean the logistics is the same.
You go to the top, there arevery few animals, very few
individuals, and very big.
Because the amount of energyfrom the bottom of the pyramid
to the top decrease a lot.
A lot of this energy that iscontained into the glucose, into
the sugar basically is lost inthe, into the environment at
(16:35):
every passage in form of heat.
So you get to the top, there'snot much energy left.
This why we don't have the sameamount of great white as we have
a sardines or anchovies, orherrings.
The smaller fishes are much morenumerous, so they are much less
vulnerable while the animals atthe top, they are much more
(16:57):
vulnerable.
Depending by the area we counttheir numbers in hundred.
Or in thousands if if some verylucky area.
Nobody knows actually how manygreat whites that are in the
Western Cape.
Some scientists say 400, somesay 200, some say 2000.
The problem is that it'simpossible to count these
(17:20):
animals.
You can count animals likedolphins, orcas, humpback whales
because they're mammals.
They're forced to come to thesurface to breathe.
But sharks are fishes.
You can tag them, you canidentify them by the shape of
the dorsal fin or the patterncoloration, but still, it is
(17:42):
impossible even because greatwhites don't stay in the same
area all the time.
They move a lot.
Some may stay longer times in agiven area.
Some other move a lot, some fromSouth Africa to Australia,
sometimes they come back.
So you have very differentpatterns of movement.
It's not like a proper migratoryspecies.
Kate (18:04):
And does that make Shark research and field work quite
difficult?
Alessandro (18:07):
Yeah.
Clearly it is difficult.
We used to work with orcas inNorway.
It is much easier because theymust come at the surface all the
time.
Also big dorsal fin, they blow.
So from a distance you can spotthem easily, you know?
And also they travel inside thefjords, so it's quite narrow
(18:29):
areas.
Kate (18:29):
And they travel in packs too, don't they?
Alessandro (18:31):
Yeah, that's it.
So it's much easier to observethem, to find them.
With great whites, they don'tswim at the surface with the
dorsal fin out the water all thetime, like in the movies So
actually when you see themswimming like that with the
dorsal fin out the water,usually it's because we are
using some chum or some bait toattract them at the surface.
(18:54):
Or when they are hunting, likethey're hunting, the seals, they
used to spend a lot of time on asurface.
Otherwise they don't have areason to stay at the surface.
Most of the time they will spendtheir time between the surface
and down to about 17 meters.
They can swim and dive muchdeeper than that, but they use
mostly the first 40 meters ofwaters and they favor the first
(19:18):
15, 17 meters of water.
But not with the dorsal fin outon the surface.
So it's very difficult.
There is this idea that we musttag all the great whites to
follow the movements for me,that's nonsense.
In the past tagging was usedmostly to see the movement of a
(19:40):
species by tagging a fewindividuals.
That was the idea.
We take a few individuals and weunderstand the movements of the
entire species.
That's a very good idea becausewhen you do that, you can find
out if it is proper migratoryspecies.
Kate (19:57):
Migratory species tend to move based on changing seasons,
primarily driven by watertemperature.
However, most Shark speciesaren't a proper migratory
species.
They're philopatric, meaningthey move within specific areas,
depending on the time of year,driven by factors such as food
availability or reproductiveneeds.
So when sharks are tagged forresearch purposes, their
(20:20):
movements don't actually revealsignificant migration patterns.
Instead, the data often portraysindividual sharks returning to
their favorite dinner or datespots.
Alessandro (20:30):
And we know those spots.
Like here, Seal Island in FalseBay or like the island in in
Gans Bay or in Mossel Baybecause there is a big source of
food.
You will see them coming shortlyafter the period where the seals
start to give birth.
And that's what the philopatricAnimals do.
They choose a place.
(20:51):
They come back usually everyyear at that time of the year,
but we know these spots, so tosee where they go in the
meantime, it's quite pointless.
We can already tell where theygo.
They go everywhere.
Kate (21:03):
So what are some common misconceptions about sharks?
Alessandro (21:07):
I think the most common is about sharks actually
being interested in attackingand eating people.
We have 540 species of sharks inthe world, and we know for sure
because there have been nowdecades of research on Shark
bites, Shark attacks.
That when it comes to Sharkbites, only about 20 species can
(21:29):
be considered actually dangerousto humans, and the only three
species can be considered verydangerous.
And these three species clearlyare the great white, the tiger
Shark and the bull Shark.
So you consider these speciesand you put together all the 540
pieces of sharks in the world.
How many people are bitten bysharks in the world per year?
(21:53):
So the data tell us that thereis about 100 people that are
bitten by Shark per year.
This may vary depending by year.
And only 10 of these, or evenless depending by year, are
actually killed by sharks.
So you see that the idea of thekiller Shark is totally wrong.
(22:14):
Actually, sharks are notinterested in humans, and this
data prove that that's actuallythe case.
There is no special sharks whichis interested in eating people.
Kate (22:26):
So I know when whales die or get beached, the gases inside
them build up and sometimeswhales will explode.
Does that ever happens tosharks?
And what happens when sharksdie?
Do they rise to the surface orfall right to the bottom of the
ocean?
Alessandro (22:43):
The sharks are cartilaginous fishes.
They don't have a, a swimbladder or gas bladder.
So they don't have a an organwhich is deputed to the buoyancy
control.
So what happened?
They have a huge liver and alsoa very light skeleton, which is
made in cartilage.
This why it's so light, theliver is filled with oil with a
(23:04):
very low specific weight.
And the liver may account up toabout 20% of the body weight.
So what happens is that theShark is still slightly heavier
than seawater.
This is why if a Shark stopsswimming, will slowly sink to
the bottom.
This is why when you see theShark in the column of water,
they're always swimming andnever completely still.
(23:26):
What happens is that when theydie, they usually just sink to
the bottom.
I mean slowly, but they stillsink to the bottom.
But clearly sometimes because ofdecomposition processes, they
may go back to the surface andkind of float or being washed
ashore.
Kate (23:42):
So does that mean the bottom of the ocean is like a
Shark graveyard?
Alessandro (23:46):
Yes, absolutely.
Because also when we talk aboutsharks being a very ancient
group, which appeared on Earthabout 435 million years ago,
they have such a longevolutionary history, and as we
say, their skeleton is made ofcartilage.
So we have such a huge amount ofspecies of sharks in this long
(24:08):
evolutionary history.
And also the lifespan of a Sharkis usually pretty long, maybe 10
years, depending by thesespecies, maybe 50 years
depending by species.
Probably the most common sharkin the world has a maximum life
span, or 90 years or 100 years.
Every single Shark produce a lotof teeth because they replace
(24:32):
their teeth during their entirelife.
Kate (24:35):
Okay, so sharks have been here for millions of years, live
on average from two to 50 years,and have up to 300 teeth in
their mouth during their lives.
So can you imagine the bottom ofthe ocean four is probably just
fields upon fields of calcifiedShark teeth fossils.
Alessandro (24:51):
So really the bottom of the ocean is kind of a
graveyard for sharks, as yousaid.
This is why we find so manyfossil teeth of sharks.
Kate (25:00):
Do sharks have any friends in the ocean or just prey?
Alessandro (25:05):
Yeah, that's a good question.
It's an interesting question.
I usually put in my books like asmall chapter about the friends
of sharks in the, I mean, theseare kind of mutualistic
relationships because we havepilot fishes and remoras
specifically.
They used to stay with sharks.
Sometimes small sharks,sometimes big sharks.
(25:25):
The fact is that the pilotfishes and remoras have a kind
of similar relationship tosharks.
We say it's mutualistic becauseboth parts benefit from the
relationship.
So what happens that thosefishes, those bony fishes, feed
on the offals of the meals ofthe shark.
So they just wait, the Shark getthe prey, and then they will
(25:48):
take the scrap of food, but atthe same time, by swimming close
to the Shark, by staying closeto the Shark, they get some kind
of a passive protection becausenot many predator will approach
you if you're close to a bigpredator like a Shark.
Also, the relationship is goodfor the Shark because those
fishes will feed on the parasiteon the skin of the Shark.
(26:12):
So all species of sharks get alot of parasite, mostly
crustacean parasite that we callcopepods.
You may find them on the skin,on the gills and the cloaca, so
the pilot fish and the remorashave the Shark to get rid of at
least part of those parasites.
Kate (26:29):
The Remora also have a very unique anatomical feature
in the form of its dorsal fin,which acts as a suction disc
that helps it attach to the skinof a Shark.
Remoras will often seize theopportunity to clinging onto a
shark's skin as it's turning astrategic move that allows them
to conserve energy efficiently.
Basically, they're the OGclingers of the sea.
Alessandro (26:52):
So you see, they're very clever, And sometimes they
can also eat the excrements ofthe sharks.
We know that this kindrelationship is not perfect,
because sometimes pilot fishesand sometimes even remoras are
found in a stomach of a Shark.
So sometimes the predator willactually eat those fishes, but
probably doesn't happen veryoften.
Kate (27:12):
So you're really playing with fire when you make friends
with a Shark.
Alessandro (27:14):
Yeah.
Kate (27:15):
So at my local beach in Australia, we have Shark nets
and smart drum lines, whichcause concern in some people for
their ability to attract sharksor also attract bycatch.
How can we as ocean users, sosurfers and ocean swimmers
become comfortable with sharingthe ocean with animals like
sharks?
Alessandro (27:36):
Yeah, I think that we are the only species of
animals which is not willing toshare environment with other
species.
And we see that all over theworld, not only with the sea,
but also on land.
Just think for example, all theproblems we have in Europe with
wolfs and foxes.
We nearly destroyed thepopulation.
These uh, predator.
(27:58):
And Now we do a lot of work torebuild these populations, but
still, every time there will bea big discussion, big fight on a
political level to reduce thepopulation.
Again, Which is crazy to mebecause these animals were here
much before than humans.
They have all the rights that wehave.
(28:18):
We always think about ourrights.
We have the rights to use theenvironment.
We have the rights to dive.
We have the right to surf.
We have the right to swim.
Actually that's a very wrongpoint of view, like a childish
point of view, in my opinion.
We have the right to use theenvironment.
We have the rights to shareenvironment.
(28:39):
So I think that uh, the mostpowerful tool in this sense is
education.
You know, it's the ocean.
The Shark will keep on coming,you know, and also we are
killing more and more of theirfood.
So some of them may actually bewilling to bite more people
because they're coming morecloser to shore to look for
(29:00):
food.
Many times when they bite peoplejust exploratory behaviour.
Sometimes it's targetingpractice, but we know there have
been a few cases of species likea bull and a tiger Shark
actually eating the person.
But the problem is that we muststop thinking that we have the
freedom to do everything and theother species have no rights
(29:23):
because we must share theenvironment.
It's much more important to keepthe environment healthy and not
killing animals, than justbeing, having the freedom to use
the environment to do whateveryou want.
Kate (29:39):
What's the most popular question you get about sharks?
Alessandro (29:43):
recently, the most common question I get is about
the increase in number ofsharks, which is clearly not
the, the, the, the, the case.
Sharks are decreasing.
Badly decreasing all over theworld.
Almost all the species,especially medium sized and big
sized Shark, larger sized Shark,these are the most massively
(30:04):
decreasing.
But people still getting theidea, there are more and more
sharks for the simple reason.
They see more and more pictures,videos posted over the social
media.
And that's crazy.
Because just think 50 years ago,a guy see a blue Shark near the
beach in Sicily.
Nobody will ever knew about thiscase.
(30:25):
Now the guy, see that blue Sharknear the beach in Sicily?
Take a picture or a video andpost it on a social media.
maybe again, it went viral.
And then million of people willsee that and they will see,
okay, oh, I didn't even knowthere were sharks in Sicily.
You know, all this kind ofstuff.
It's just getting uh, outtacontrol.
(30:47):
It's crazy.
So people actually think thereis a, a real increase in the
number of sharks all over theworld.
But I tell you that's not thecase.
The sharks, sharks aredecreasing, massively decreasing
because of over fishing, divefishing, target fishing, by
catch and finning and all thiskind of stuff.
(31:09):
So that's I think that's a veryimportant message to bring to
the people.
Kate (31:16):
Alessandro shows me a case with different types of Shark
teeth.
Alessandro (31:19):
So for example, we have some teeth of sharks to
show the different shape, whichis related to the different diet
of the species.
So for example, we have atriangular serrated teeth like
in the case that the Great WhiteShark or the tiger Shark or the
bull Shark.
Also, we have a narrower teethmore pointed that are used to
catch very fast swimming preylike uh, bony fishes or
(31:43):
schooling fishes and or tearingthe prey apart, like in the case
of the Sand Tiger Shark.
And also we have teeth with morecusp and cusp plates, like in
the case of the Cow Shark and wehave the Bluntnose Sixgill
Shark.
Here also we have some egg casesof sharks because some species
(32:05):
of Shark are actually oviparous,so they lay eggs.
That's the specific case of theCatsharks.
Also, I have a Bullhead egg caseI recently took at the in the
area of the Neptune Islands.
That's, that's pretty big.
But it can get much bigger thanthat.
Kate (32:22):
We see a small anatomical model of a great white,
Alessandro (32:25):
So I built this anatomical model of a great
white that's been quite funnybecause there is no kind of an
atlas of an anatomy of the greatwhite.
Kate (32:35):
What's the little fish in is?
Alessandro (32:37):
That's stomach.
You see the stomach of a Sharkis J shaped.
The first part is bigger and isused to store the food.
In this case, that's albacore.
So it's albacore, a species oftuna You see that it is eaten
almost whole, it misses only thecaudal fin because the shark cut
the caudal fin, the bite, so theprey cannot escape.
(32:59):
So that's the space where thefood is stored.
The second part of the J, thesmaller part of the stomach is
where the food is actuallydigested, but sometimes can be
stored even for weeks beforebeing digested.
Kate (33:12):
Eww.
Alessandro (33:13):
So the body will digest the food when it's really
needed, you know?
And also that's a pregnantfemale.
So you see that inside theuterus you can see an embryo.
It's pretty big, but not fullterm yet.
So you see that there is theyolk sac of the embryo still
containing yolk, stillcontaining food.
When he will be ready to beborn, the yolk sack will be
(33:36):
completely reabsorbed.
Kate (33:38):
when it comes to the gestation period of sharks, it
varies depending on the species.
But for the majority it spansaround 10 months.
Alessandro (33:45):
But for the species like great white, is it 12
months, so it's longer thanhumans?
Very, very long.
This is actually one of thereasons why Shark are so
vulnerable.
It take a long time to attainsexual maturity.
They have very long gestationand they don't produce thousands
or millions of eggs per time,like many bony fishes, but just
a few units.
(34:06):
So for great white, the littersize is from two to 17 pups.
So they are very vulnerablebecause of the reproductive
methods.
Then here we have this decoythat's a seal shaped decoy that
is used to be tow behind theboat.
We tow the decoy behind theboat, and maybe we get lucky in
(34:27):
one Shark with breach on it.
Maybe people think that thegreat white will breach on the
decoy because they think it's areal seal.
I don't believe this theory.
I think that it doesn't smelllike a seal.
It doesn't move like a seal.
It really doesn't look like aseal at all.
So I think that for most greatwhite, they do that.
Just targeting practice.
This is why even when we have alot of great whites in the area,
(34:50):
you may spend several daysbefore seeing one breach on the
decoy, but still they'll breachall the time on the real deal,
on the real seal.
Anyway, all these bites that youcan see on the decoy, they are
proper bites of great whites.
Here we have a beautiful modelof, of an actual great white 5.5
meter female that we observed inSouth Australia, the Neptune
(35:13):
Islands.
That is been made by a Russianartist.
So you see that it is verybeautiful and these all the
proportions are perfect.
That's an actual model of thatShark you can see the picture.
Kate (35:26):
The model measures about 15 centimeters and is
intricately suspended in resin.
Nearby is a photo of the Sharkcaptured by Alessandro.
A detail worth noting is theimpressive accuracy of the model
that faithfully replicates eventhe minute detail, such as the
distinctive bite scar seen inthe photograph.
Alessandro (35:44):
The maximum size of great white that I, I've been
able to demonstrate with mystudies is 6.6 meters.
Kate (35:50):
Oof.
Alessandro (35:50):
But is almost impossible to see animals of
that size.
So when you see a five metergreat white, probably is going
to be the biggest you're goingto see in your life.
So to see a 5.5 meter greatwhite in so many years, so many
expeditions, that was very, verylucky.
And then here at the bottom wehave several teeth of extinct
(36:12):
great whites.
So that's, these are fossilteeth of great white.
Kate (36:16):
biggest one was from a Shark called Otodus Megalodon,
which literally means big tooth.
It was a type of mackerel Sharkthat existed from 23 million to
3 million years ago.
Alessandro (36:27):
Many people asked me, you're still alive, because
they saw kind of fakedocumentary that was aired on
Discovery Channel years ago,that was fake This animal has
gone extinct million years ago.
Recent studies say that he mayattain it up to 16 meters in
length, but the more recentstudy, again, say that maybe it
(36:48):
was up to 19 or 20 meters.
And also we have this section,we have ten signs about the
biology of sharks.
Just explain the basic factsabout their classification,
anatomy, feeding, reproduction,and then we have a specialized
library.
And there are more than 100books on sharks that I collected
(37:12):
in my activity.
Kate (37:13):
And how many books have you published?
Alessandro (37:16):
Here there is the section with my own books.
I published 20 books so far, allabout sharks.
And also there is a smallsection of the books uh, by
other authors to which Icontributed mostly with my
illustrations.
And uh, you know, I also wantedto show the people the actual
size of sharks.
But that's a small space.
So there was no way to have akind of a five meter great white
(37:39):
inside the space.
You know, then people will notbe able to even enter.
So I ask a local artist thatproduce this kind of
silhouettes, made in wood,showing the actual size of
different species of sharks thatwe can actually find in South
African water.
So you see, for example, thecommon thresher Shark, the
sandbar Shark, the cow Shark,the shortfin mako, the
(38:03):
Smooth-hound, the SouthernAfrican Frilled Shark, the Piked
dogfish.
Yeah, the Pygmy Shark and theThorny lanternshark.
These are two of the smallestsharks found in the world.
Kate (38:15):
Oh, wow.
They're six centimeters atbirth.
Alessandro (38:17):
Yeah.
So you see that.
These that you can see in thesesilhouettes are not the maximum
size of the species.
Because for example, the biggestone we have here is the Shortfin
Mako is 2.5 meters.
That's the size of sexualmaturity for all those species.
So the size when they becomesexually adult.
(38:37):
And the last thing, I had acouple of drawings of
illustrations in color made bypencil.
These were made by my father,Emilio de Maddalena years ago.
And this the, the biggest onethat was based on a photo took
by Valerie Taylor dangerous Reefin South Australia.
(38:58):
He, my father didn't knowanything about sharks.
He just copy the picture.
But the result to me is stillthe best drawing I've seen of a
Shark in my life.
So, just a way to remember myfather.
And the last thing I want tosay, that this small museum is
dedicated to Sauro Baldi that'sthe the Dad of my wife.
(39:19):
Because we built this spacetogether with my wife, biologist
Alessandra Baldi.
We thought it was a good idea todedicate the museum to him
because without his support, itwould be impossible to create
this space.
Kate (39:32):
Thank you so much for the tour and the interview and for
coming on the podcast,alessandro.
Alessandro (39:37):
It's my pleasure.
Thank you so much for theinvitation.
Kate (39:45):
Currently, the Shark museum is open for scheduled
lectures or an appointment onlywith Alessandro.
The lectures are in person, butin the future, Alessandro may
offer online options.
The lecture topics include dietand predatory tactics of sharks,
south African sharks, andethical pra ethical practices in
Shark cage diving.
(40:05):
He invites other Shark and oceanspecialists such as Professor
Mike Bruton and Wildlife Oceanphotographer Chris Fallows to
contribute their expertise aswell.
So folks don't get your Sharkinformation on social media.
As much as I feel threatened bysharks, I also feel a really
(40:25):
strong affinity for thesecreatures.
Sharks are a vital part of ourmarine ecosystems, and if we try
and change the balance of sharksor fish or other ocean
variables, we could be askingfor a disaster.
And just like Bruce, the Sharksays, in Finding Nemo fish are
friends, not food.
So let's think of sharks asfriends, and not foe, or any
(40:46):
other descriptive word thatstarts with the letter F.
Thanks for listening to Roadshowand Tell.
If you enjoyed this deep diveinto a specialty museum, make
sure you subscribe so you don'tmiss an episode.
We're a new podcast.
So if you wanna help support us,please share it with a friend
and leave a rating and review.
(41:08):
If you are involved with or knowof a regional or specialty
museum that should be featured,please get in touch at
roadshowandtell@gmail.com.
I'm your host, Kate.
Roadshow and Tell was edited andproduced on the lands of the
Gadigal people.
I acknowledge the TraditionalCustodians of the various lands
(41:29):
on which you may be listeningfrom, and the lands that the
museums featured in this podcastreside on.
I also acknowledge anyAboriginal or Torres Strait
Islander people listening tothis podcast.
I pay my respects to elderspast, present, and emerging, and
celebrate the diversity ofAboriginal peoples and their
ongoing cultures and connectionsto the lands And waters of
(41:52):
Australia.
Welcome to Roadshow and Tell, a podcast for people
hoping to improve their pubtrivia team score.
I'm your host, Kate, and I'llvisit museums so you can learn
things you never knew you wantedto.
In this episode, we visit theShark Museum in Simon's Town,
South Africa.
(00:37):
Simon's Town is just a 40 minutedrive from Cape Town City
Center, and is a gateway to theMarine Big Five, that is whales,
sharks, penguins, seals, anddolphins.
The Shark Museum is a passionproject of biologist and Shark
expert Alessandro de Maddalena.
It's a tiny but picturesque roomthat overlooks the crystal clear
(00:58):
blue waters and quaint buildingsof Simon's Town.
It's filled with so much Sharkparaphernalia and is also used
primarily as a space to hostlectures about all things
sharks.
And the best thing about talkingwith an Italian Shark expert?
The delightful way he describessharks:
Alessandro (01:16):
hammerhead sharks,, Cow Shark, Blue Shark, Mako
Sharks the common thresherShark, the sandbar Shark, the
Southern African Frilled Shark,the Piked dogfish.
The Pygmy Shark and the Thornylanternshark
Kate (01:30):
So listen on to hear about how cage diving can support
Shark conservation, why Jawstaught us poorly about great
whites, and why we should all beconcerned about decreasing
populations of those chompy boysin our waters.
Alessandro (01:46):
My name is Alessandro De Maddalena.
I've been working on sharks formany years.
I'm now 52, and I started to beinterested in sharks when I was
still a kid about seven, eightyears old.
And then I decided I want tostudy the sharks and more
specifically, great white.
I did my studies in naturalscience at the university in
(02:08):
Milan.
I took my master degree and thenI started to do work about the
presence of the great white inthe Mediterranean Sea.
And I built a very big database,about 600 cases of great whites
recorded, both in historical andpresent day.
And from there I started topublish scientific papers about
(02:31):
the biology of the great whitesin the Mediterranean.
Then I extended to other speciesin the same area, like
hammerhead sharks, Cow Shark,Blue Shark, Mako Sharks.
And in 2010 I started to workwith a cage dive operator here
in Simon's Town, South Africa.
So I started to work with ChrisFallows and his wife Monique of
(02:54):
Apex Shark Expeditions.
And then I started to host GreatWhite Expedition with Shark
biology courses.
In the beginning was like okay,I want to try to do this, but it
went so well become a very bigpart of my life and my work.
So I moved here in Simon's Townin 2012 with my family, which
(03:17):
means 10 years ago.
I continue to work articles andbooks about sharks also taking
photos, drawing illustrations,everything about sharks, giving
lectures.
Also started to work inAustralia hosting similar Great
White Shark expedition withRodney Fox Shark expedition, so
the Neptune Islands SouthAustralia.
(03:38):
And later also started to hostorca expedition or killer whale
expeditions in Norway.
And one year ago we opened thistiny Shark museum in Simon's
Town.
Kate (03:50):
Wow.
So what would seven year oldAlessandro who wants to learn
about sharks say to your 52 yearold self now?
Alessandro (03:57):
Yeah.
You know, that for me, thestrangest thing is that when I
was seven, eight years old, Iwatched my very first
documentary, the television, youknow, at the time there was no
internet.
Otherwise, there were only acouple of television channels in
Italy.
So you didn't get many Sharkdocumentaries or none at all?
Kate (04:17):
Not like now.
Alessandro (04:18):
Yeah.
You see very different.
So I watched my very first Greatwhite documentary when I was
that age and uh, it wasdocumentary filmed with Rodney
Fox in South Australia, and nowI'm 52 and I'm working for that
man.
You know, life is so strange andfull of surprise.
Kate (04:36):
So how did the Shark Museum come to be?
Obviously your expeditions weregoing really well.
Why did you start the SharkMuseum?
Alessandro (04:43):
Again, it's a dream of my childhood.
When I was a kid I used to buildtiny models of a shark museum
and that was a kind of an ideastuck in my mind.
What happened is that a coupleyears ago now, we had the, the
chance buying the property.
And this place was a special oneto me because that was actually
(05:06):
part of a b'n'b where I used tostay during my very first great
white expedition in 2010.
So when they put it on sale, Ifelt like, okay, maybe that's
the right time in the rightplace.
We renovated the place and didsome major work and then one
year ago we were able to openthis tiny museum.
(05:29):
I mean, it's very, very small,but still this is something
important to me.
That's uh, the place I wanted tohave to be able to do my
education activities mostly.
Kate (05:40):
So you're mostly interested in great whites.
Why do you think you're mostinterested in the scariest
Shark?
Alessandro (05:45):
Yeah.
Everybody are very interested ingreat whites because they're the
most dangerous species ofsharks.
Still not as dangerous as manypeople think, but it is true.
It's the most dangerous speciesof Shark.
We cannot deny it.
And lot of people actually gotinterested in sharks because of
the movie Jaws.
(06:06):
This is not what happened to mebecause I actually watched Jaws
when I was a teenager, so mypassion started before with
documentaries and books.
Only later I had the chance ofwatching that kind of movies.
Anyway, the main reason why I'minterested in great whites is
just because they are veryprehistoric.
They look like prehistoricanimals.
(06:27):
You can be in the water with anyspecies of Shark.
The smallest one, the biggestone, and all of them are so
beautiful.
But the great white looks mostlike a very ancient, prehistoric
animal.
When I was a kid, I wanted to bea paleontologist.
I want to study dinosaurs, butyou know, I was reading these
(06:49):
books about dinosaurs.
They're all dead.
You know, there is no chanceyou, one day you are going to
see one a live dinosaur like inJurassic Park.
So when I saw my first greatwhite on the screen, I talk,
okay, this one looks like aprehistoric animal, but he's
still alive.
As I say, those species ofsharks are beautiful, but a
(07:09):
great white is just moremajestic and more ancient the
way it looks I mean.
Kate (07:15):
Okay.
I don't know about calling GreatWhites majestic, but they're
definitely funny lookingcreatures.
you might remember Alessandrosaid he studied sharks in the
Mediterranean.
Alessandro (07:26):
Yeah.
You know that, still today, mostpeople living on the
Mediterranean coast don't knowabout the presence.
The And the reason is verysimple.
There used to be a very strongpopulation in Mediterranean,
like centuries ago.
And then about one century ago,the population in Mediterranean
started to decline.
(07:46):
So now there are very, very fewgreat whites left in the
Mediterranean.
So every time there will be onegreat white spotted, a lot of
media will report the news, likeyou know, it's kind of the, the
first time a great white spot.
That's not true.
that's totally wrong.
Actually, the Mediterranean wasthe very first place where the
(08:09):
species, the great white wasfirst described.
Kate (08:12):
That's right.
The earliest recorded Sharkattack ever happened in the
Mediterranean.
It's all thanks to a vasediscovered in Naples dating back
to 725 bc.
Alessandro (08:22):
So they always been there.
They always reproduce there.
They always fed there.
It is simply that like it ishappening in so many parts of
the world nowadays.
The Mediterranean started beforethe humans started to kill them
and to reduce their population.
Now there's just a tinypercentage of what the
(08:44):
population used to be before.
That's why people inMediterranean countries are not
aware of the great whitepresence because it is so rare
to see them, you know?
Kate (08:54):
Speaking of that, can you tell us about what's happening
with this Shark populations inFalse Bay and Mossel Bay?
For reference, False Bay andMossel Bay are two bays in Cape
town, which are known to beparticularly sharky
Alessandro (09:07):
Yeah, let's say that what's happening here, it's just
the same happened before inMediterranean.
I always underline this aspectbecause people usually tend to
be very slow in learning.
We do a lot of damage to naturearound the world.
So we must take an example ofwhat happen in other countries,
(09:29):
to not repeat the same mistakes,but you see it is not happening.
So we have some areas of theworld where the population of
great whites are properlymanaged, but not many.
In most cases, people are justfishing everything and not
caring about these animals.
And then in many countries,great whites or other species
(09:49):
are protected on paper, but thenthere is no enforcement or very
little enforcement.
No control.
And then you know, everybody gothere and fish the sharks, fish
for their prey, kill them onpurpose, or kill them as
bycatch, meaning trying to catchother species of fishes, and
then by mistake, I kill a greatwhite.
(10:10):
You know, that's bycatchhappening everywhere around the
world.
It is very sad because you canprotect as many species as you
want.
But if it's not a properprotection, it is just written
on paper, it is useless.
And now what we are witnessingis that everywhere the number of
(10:31):
species that are protected isbecoming longer and longer, but
enforcement is not increasing.
So you understand it's verydifficult to actually protect
all those species if there isvery little enforcement.
So what's happening here inFalse Bay, Mossel Bay, and let's
say all the waters in theWestern Cape is just the same.
(10:53):
South Africa's been the veryfirst country in world to
protect the white in 1991.
So it's something like anhistorical record, something to
be proud of for South Africanpeople.
The problem is that in thebeginning it worked pretty well
because if you teach people thatanimals can also be use useful
to bring more riches to thecountry more I mean more funds
(11:18):
to the country, more tourism,it's good for the shops, for
hotels, for the restaurant, notonly for the cage diving
industry or the diving industryfor everybody.
So if you properly useecotourism, that's very powerful
tool to teach the entirecommunity, not only people
working with wild animals, thatthese animals are much more
(11:42):
worth when they're alive thanwhen they're dead.
This has been done in so manycountries.
Just think, for example, theMaldives.
All species of Shark areprotected because they make so
much money with the divingindustry.
People dive and travel all overthe world from any country to go
to the Maldives specifically todive with sharks.
(12:05):
If this population are wipedout, then you lose all this kind
of tourists.
The same thing working very wellwith great whites in South
Africa, so people were coming toFalse Bay, Gansbaii, Mossel Bay
specifically to cage dive withgreat whites.
And this if properly regulated,is a wonderful activity.
If it's not properly regulatedmay be a problem for the Shark
(12:29):
and the public, you know?
Then what happen in the recentyears, we saw the number of
sharks decreasing continuouslywell before those two orcas
arrived on the spot.
Kate (12:41):
so, like I said, False Bay has earned a reputation as a
very sharky area.
However, a phenomenon has beenobserved in recent times that
there is an apparent decrease inShark numbers associated with
the presence of two orcas,affectionately known as port and
starboard.
The two orcas are said to beresponsible for at least seven
(13:03):
great white deaths since 2015.
While pods of orcas have beenvisiting False Bay for years,
they've never hunted sharks.
Some scientists hypothesizedthat the sharks are being scared
away from False Bay by thisbehavior, explaining the decline
in sightings.
Alessandro (13:19):
Now a lot of people, a lot of media are blaming two
orcas for the disappearance ofgreat whites in the area.
It's not like that.
The orcas chase the Shark, killa couple of them per year, which
is nothing for a population thatis estimated to be of several
hundreds, but sometimes theychase them away.
(13:39):
But the sharks, if they're stillthere, if they're still alive,
they come back.
You know, if this is nothappening, just because the
number of sharks started todecrease well before the orcas
arrived.
So you understand the decreaseof sharks is because of fishing,
not because of the orcas.
Kate (14:00):
Because there's not enough fish in the Bay for them to
Alessandro (14:03):
fish there.
There is too much fishing in theentire area, even in offshore
waters.
So what happens?
Too much fishing kill sharkssometimes.
So you see that is not onlybecause sharks are culled.
By poachers or by bycatch, youknow?
But also because if we killtheir food, they're going to
(14:26):
disappear or to move to otherareas where there is more food,
you know?
But there must be other areaswhere there is more food.
Otherwise they cannot survive.
Kate (14:37):
And what happens if we wipe out sharks?
I know a lot of people proculling sharks.
What would happen if we wipedout that top apex predator from
our oceans?
Alessandro (14:46):
You know, there are many affects that is very
difficult to predict.
So what happens is that you wipeout the population of an apex
predator.
What's happening, the apexpredator is called apex predator
because is at the top of animaginary pyramid.
In this pyramid you have at thebottom, you have the creatures,
(15:09):
the organism, they do thephotosynthesis.
So we have the phytoplanktonbasically in the ocean.
Then we have the zooplankton,they feed on the phytoplankton.
The producers, thephytoplankton, clearly by
photosynthesis, they create theenergy.
They synthesize the glucose,which is used by all the other
levels.
So it's used by the zooplankton,it's used by sardines,
(15:34):
anchovies, small fish.
And then you go up, you findbigger fishes like snoeks, like
barracudas, like tuna, and thenlike swordfish, you go towards
the top of the pyramid and theamount of fish, the amount of
individuals decrease and theirsize getting bigger.
Kate (15:53):
So at the top of the pyramid is you guessed it, those
big chompy boys.
The actual species of the apexpredators will depend on your
location.
In tropical waters, it could bethe tiger sharks or great
hammerheads.
In South Africa, it's probablygreat Whites or in Norway or
Antarctica, it's probably orcas.
Alessandro (16:12):
But I mean the logistics is the same.
You go to the top, there arevery few animals, very few
individuals, and very big.
Because the amount of energyfrom the bottom of the pyramid
to the top decrease a lot.
A lot of this energy that iscontained into the glucose, into
the sugar basically is lost inthe, into the environment at
(16:35):
every passage in form of heat.
So you get to the top, there'snot much energy left.
This why we don't have the sameamount of great white as we have
a sardines or anchovies, orherrings.
The smaller fishes are much morenumerous, so they are much less
vulnerable while the animals atthe top, they are much more
(16:57):
vulnerable.
Depending by the area we counttheir numbers in hundred.
Or in thousands if if some verylucky area.
Nobody knows actually how manygreat whites that are in the
Western Cape.
Some scientists say 400, somesay 200, some say 2000.
The problem is that it'simpossible to count these
(17:20):
animals.
You can count animals likedolphins, orcas, humpback whales
because they're mammals.
They're forced to come to thesurface to breathe.
But sharks are fishes.
You can tag them, you canidentify them by the shape of
the dorsal fin or the patterncoloration, but still, it is
(17:42):
impossible even because greatwhites don't stay in the same
area all the time.
They move a lot.
Some may stay longer times in agiven area.
Some other move a lot, some fromSouth Africa to Australia,
sometimes they come back.
So you have very differentpatterns of movement.
It's not like a proper migratoryspecies.
Kate (18:04):
And does that make Shark research and field work quite
difficult?
Alessandro (18:07):
Yeah.
Clearly it is difficult.
We used to work with orcas inNorway.
It is much easier because theymust come at the surface all the
time.
Also big dorsal fin, they blow.
So from a distance you can spotthem easily, you know?
And also they travel inside thefjords, so it's quite narrow
(18:29):
areas.
Kate (18:29):
And they travel in packs too, don't they?
Alessandro (18:31):
Yeah, that's it.
So it's much easier to observethem, to find them.
With great whites, they don'tswim at the surface with the
dorsal fin out the water all thetime, like in the movies So
actually when you see themswimming like that with the
dorsal fin out the water,usually it's because we are
using some chum or some bait toattract them at the surface.
(18:54):
Or when they are hunting, likethey're hunting, the seals, they
used to spend a lot of time on asurface.
Otherwise they don't have areason to stay at the surface.
Most of the time they will spendtheir time between the surface
and down to about 17 meters.
They can swim and dive muchdeeper than that, but they use
mostly the first 40 meters ofwaters and they favor the first
(19:18):
15, 17 meters of water.
But not with the dorsal fin outon the surface.
So it's very difficult.
There is this idea that we musttag all the great whites to
follow the movements for me,that's nonsense.
In the past tagging was usedmostly to see the movement of a
(19:40):
species by tagging a fewindividuals.
That was the idea.
We take a few individuals and weunderstand the movements of the
entire species.
That's a very good idea becausewhen you do that, you can find
out if it is proper migratoryspecies.
Kate (19:57):
Migratory species tend to move based on changing seasons,
primarily driven by watertemperature.
However, most Shark speciesaren't a proper migratory
species.
They're philopatric, meaningthey move within specific areas,
depending on the time of year,driven by factors such as food
availability or reproductiveneeds.
So when sharks are tagged forresearch purposes, their
(20:20):
movements don't actually revealsignificant migration patterns.
Instead, the data often portraysindividual sharks returning to
their favorite dinner or datespots.
Alessandro (20:30):
And we know those spots.
Like here, Seal Island in FalseBay or like the island in in
Gans Bay or in Mossel Baybecause there is a big source of
food.
You will see them coming shortlyafter the period where the seals
start to give birth.
And that's what the philopatricAnimals do.
They choose a place.
(20:51):
They come back usually everyyear at that time of the year,
but we know these spots, so tosee where they go in the
meantime, it's quite pointless.
We can already tell where theygo.
They go everywhere.
Kate (21:03):
So what are some common misconceptions about sharks?
Alessandro (21:07):
I think the most common is about sharks actually
being interested in attackingand eating people.
We have 540 species of sharks inthe world, and we know for sure
because there have been nowdecades of research on Shark
bites, Shark attacks.
That when it comes to Sharkbites, only about 20 species can
(21:29):
be considered actually dangerousto humans, and the only three
species can be considered verydangerous.
And these three species clearlyare the great white, the tiger
Shark and the bull Shark.
So you consider these speciesand you put together all the 540
pieces of sharks in the world.
How many people are bitten bysharks in the world per year?
(21:53):
So the data tell us that thereis about 100 people that are
bitten by Shark per year.
This may vary depending by year.
And only 10 of these, or evenless depending by year, are
actually killed by sharks.
So you see that the idea of thekiller Shark is totally wrong.
(22:14):
Actually, sharks are notinterested in humans, and this
data prove that that's actuallythe case.
There is no special sharks whichis interested in eating people.
Kate (22:26):
So I know when whales die or get beached, the gases inside
them build up and sometimeswhales will explode.
Does that ever happens tosharks?
And what happens when sharksdie?
Do they rise to the surface orfall right to the bottom of the
ocean?
Alessandro (22:43):
The sharks are cartilaginous fishes.
They don't have a, a swimbladder or gas bladder.
So they don't have a an organwhich is deputed to the buoyancy
control.
So what happened?
They have a huge liver and alsoa very light skeleton, which is
made in cartilage.
This why it's so light, theliver is filled with oil with a
(23:04):
very low specific weight.
And the liver may account up toabout 20% of the body weight.
So what happens is that theShark is still slightly heavier
than seawater.
This is why if a Shark stopsswimming, will slowly sink to
the bottom.
This is why when you see theShark in the column of water,
they're always swimming andnever completely still.
(23:26):
What happens is that when theydie, they usually just sink to
the bottom.
I mean slowly, but they stillsink to the bottom.
But clearly sometimes because ofdecomposition processes, they
may go back to the surface andkind of float or being washed
ashore.
Kate (23:42):
So does that mean the bottom of the ocean is like a
Shark graveyard?
Alessandro (23:46):
Yes, absolutely.
Because also when we talk aboutsharks being a very ancient
group, which appeared on Earthabout 435 million years ago,
they have such a longevolutionary history, and as we
say, their skeleton is made ofcartilage.
So we have such a huge amount ofspecies of sharks in this long
(24:08):
evolutionary history.
And also the lifespan of a Sharkis usually pretty long, maybe 10
years, depending by thesespecies, maybe 50 years
depending by species.
Probably the most common sharkin the world has a maximum life
span, or 90 years or 100 years.
Every single Shark produce a lotof teeth because they replace
(24:32):
their teeth during their entirelife.
Kate (24:35):
Okay, so sharks have been here for millions of years, live
on average from two to 50 years,and have up to 300 teeth in
their mouth during their lives.
So can you imagine the bottom ofthe ocean four is probably just
fields upon fields of calcifiedShark teeth fossils.
Alessandro (24:51):
So really the bottom of the ocean is kind of a
graveyard for sharks, as yousaid.
This is why we find so manyfossil teeth of sharks.
Kate (25:00):
Do sharks have any friends in the ocean or just prey?
Alessandro (25:05):
Yeah, that's a good question.
It's an interesting question.
I usually put in my books like asmall chapter about the friends
of sharks in the, I mean, theseare kind of mutualistic
relationships because we havepilot fishes and remoras
specifically.
They used to stay with sharks.
Sometimes small sharks,sometimes big sharks.
(25:25):
The fact is that the pilotfishes and remoras have a kind
of similar relationship tosharks.
We say it's mutualistic becauseboth parts benefit from the
relationship.
So what happens that thosefishes, those bony fishes, feed
on the offals of the meals ofthe shark.
So they just wait, the Shark getthe prey, and then they will
(25:48):
take the scrap of food, but atthe same time, by swimming close
to the Shark, by staying closeto the Shark, they get some kind
of a passive protection becausenot many predator will approach
you if you're close to a bigpredator like a Shark.
Also, the relationship is goodfor the Shark because those
fishes will feed on the parasiteon the skin of the Shark.
(26:12):
So all species of sharks get alot of parasite, mostly
crustacean parasite that we callcopepods.
You may find them on the skin,on the gills and the cloaca, so
the pilot fish and the remorashave the Shark to get rid of at
least part of those parasites.
Kate (26:29):
The Remora also have a very unique anatomical feature
in the form of its dorsal fin,which acts as a suction disc
that helps it attach to the skinof a Shark.
Remoras will often seize theopportunity to clinging onto a
shark's skin as it's turning astrategic move that allows them
to conserve energy efficiently.
Basically, they're the OGclingers of the sea.
Alessandro (26:52):
So you see, they're very clever, And sometimes they
can also eat the excrements ofthe sharks.
We know that this kindrelationship is not perfect,
because sometimes pilot fishesand sometimes even remoras are
found in a stomach of a Shark.
So sometimes the predator willactually eat those fishes, but
probably doesn't happen veryoften.
Kate (27:12):
So you're really playing with fire when you make friends
with a Shark.
Alessandro (27:14):
Yeah.
Kate (27:15):
So at my local beach in Australia, we have Shark nets
and smart drum lines, whichcause concern in some people for
their ability to attract sharksor also attract bycatch.
How can we as ocean users, sosurfers and ocean swimmers
become comfortable with sharingthe ocean with animals like
sharks?
Alessandro (27:36):
Yeah, I think that we are the only species of
animals which is not willing toshare environment with other
species.
And we see that all over theworld, not only with the sea,
but also on land.
Just think for example, all theproblems we have in Europe with
wolfs and foxes.
We nearly destroyed thepopulation.
These uh, predator.
(27:58):
And Now we do a lot of work torebuild these populations, but
still, every time there will bea big discussion, big fight on a
political level to reduce thepopulation.
Again, Which is crazy to mebecause these animals were here
much before than humans.
They have all the rights that wehave.
(28:18):
We always think about ourrights.
We have the rights to use theenvironment.
We have the rights to dive.
We have the right to surf.
We have the right to swim.
Actually that's a very wrongpoint of view, like a childish
point of view, in my opinion.
We have the right to use theenvironment.
We have the rights to shareenvironment.
(28:39):
So I think that uh, the mostpowerful tool in this sense is
education.
You know, it's the ocean.
The Shark will keep on coming,you know, and also we are
killing more and more of theirfood.
So some of them may actually bewilling to bite more people
because they're coming morecloser to shore to look for
(29:00):
food.
Many times when they bite peoplejust exploratory behaviour.
Sometimes it's targetingpractice, but we know there have
been a few cases of species likea bull and a tiger Shark
actually eating the person.
But the problem is that we muststop thinking that we have the
freedom to do everything and theother species have no rights
(29:23):
because we must share theenvironment.
It's much more important to keepthe environment healthy and not
killing animals, than justbeing, having the freedom to use
the environment to do whateveryou want.
Kate (29:39):
What's the most popular question you get about sharks?
Alessandro (29:43):
recently, the most common question I get is about
the increase in number ofsharks, which is clearly not
the, the, the, the, the case.
Sharks are decreasing.
Badly decreasing all over theworld.
Almost all the species,especially medium sized and big
sized Shark, larger sized Shark,these are the most massively
(30:04):
decreasing.
But people still getting theidea, there are more and more
sharks for the simple reason.
They see more and more pictures,videos posted over the social
media.
And that's crazy.
Because just think 50 years ago,a guy see a blue Shark near the
beach in Sicily.
Nobody will ever knew about thiscase.
(30:25):
Now the guy, see that blue Sharknear the beach in Sicily?
Take a picture or a video andpost it on a social media.
maybe again, it went viral.
And then million of people willsee that and they will see,
okay, oh, I didn't even knowthere were sharks in Sicily.
You know, all this kind ofstuff.
It's just getting uh, outtacontrol.
(30:47):
It's crazy.
So people actually think thereis a, a real increase in the
number of sharks all over theworld.
But I tell you that's not thecase.
The sharks, sharks aredecreasing, massively decreasing
because of over fishing, divefishing, target fishing, by
catch and finning and all thiskind of stuff.
(31:09):
So that's I think that's a veryimportant message to bring to
the people.
Kate (31:16):
Alessandro shows me a case with different types of Shark
teeth.
Alessandro (31:19):
So for example, we have some teeth of sharks to
show the different shape, whichis related to the different diet
of the species.
So for example, we have atriangular serrated teeth like
in the case that the Great WhiteShark or the tiger Shark or the
bull Shark.
Also, we have a narrower teethmore pointed that are used to
catch very fast swimming preylike uh, bony fishes or
(31:43):
schooling fishes and or tearingthe prey apart, like in the case
of the Sand Tiger Shark.
And also we have teeth with morecusp and cusp plates, like in
the case of the Cow Shark and wehave the Bluntnose Sixgill
Shark.
Here also we have some egg casesof sharks because some species
(32:05):
of Shark are actually oviparous,so they lay eggs.
That's the specific case of theCatsharks.
Also, I have a Bullhead egg caseI recently took at the in the
area of the Neptune Islands.
That's, that's pretty big.
But it can get much bigger thanthat.
Kate (32:22):
We see a small anatomical model of a great white,
Alessandro (32:25):
So I built this anatomical model of a great
white that's been quite funnybecause there is no kind of an
atlas of an anatomy of the greatwhite.
Kate (32:35):
What's the little fish in is?
Alessandro (32:37):
That's stomach.
You see the stomach of a Sharkis J shaped.
The first part is bigger and isused to store the food.
In this case, that's albacore.
So it's albacore, a species oftuna You see that it is eaten
almost whole, it misses only thecaudal fin because the shark cut
the caudal fin, the bite, so theprey cannot escape.
(32:59):
So that's the space where thefood is stored.
The second part of the J, thesmaller part of the stomach is
where the food is actuallydigested, but sometimes can be
stored even for weeks beforebeing digested.
Kate (33:12):
Eww.
Alessandro (33:13):
So the body will digest the food when it's really
needed, you know?
And also that's a pregnantfemale.
So you see that inside theuterus you can see an embryo.
It's pretty big, but not fullterm yet.
So you see that there is theyolk sac of the embryo still
containing yolk, stillcontaining food.
When he will be ready to beborn, the yolk sack will be
(33:36):
completely reabsorbed.
Kate (33:38):
when it comes to the gestation period of sharks, it
varies depending on the species.
But for the majority it spansaround 10 months.
Alessandro (33:45):
But for the species like great white, is it 12
months, so it's longer thanhumans?
Very, very long.
This is actually one of thereasons why Shark are so
vulnerable.
It take a long time to attainsexual maturity.
They have very long gestationand they don't produce thousands
or millions of eggs per time,like many bony fishes, but just
a few units.
(34:06):
So for great white, the littersize is from two to 17 pups.
So they are very vulnerablebecause of the reproductive
methods.
Then here we have this decoythat's a seal shaped decoy that
is used to be tow behind theboat.
We tow the decoy behind theboat, and maybe we get lucky in
(34:27):
one Shark with breach on it.
Maybe people think that thegreat white will breach on the
decoy because they think it's areal seal.
I don't believe this theory.
I think that it doesn't smelllike a seal.
It doesn't move like a seal.
It really doesn't look like aseal at all.
So I think that for most greatwhite, they do that.
Just targeting practice.
This is why even when we have alot of great whites in the area,
(34:50):
you may spend several daysbefore seeing one breach on the
decoy, but still they'll breachall the time on the real deal,
on the real seal.
Anyway, all these bites that youcan see on the decoy, they are
proper bites of great whites.
Here we have a beautiful modelof, of an actual great white 5.5
meter female that we observed inSouth Australia, the Neptune
(35:13):
Islands.
That is been made by a Russianartist.
So you see that it is verybeautiful and these all the
proportions are perfect.
That's an actual model of thatShark you can see the picture.
Kate (35:26):
The model measures about 15 centimeters and is
intricately suspended in resin.
Nearby is a photo of the Sharkcaptured by Alessandro.
A detail worth noting is theimpressive accuracy of the model
that faithfully replicates eventhe minute detail, such as the
distinctive bite scar seen inthe photograph.
Alessandro (35:44):
The maximum size of great white that I, I've been
able to demonstrate with mystudies is 6.6 meters.
Kate (35:50):
Oof.
Alessandro (35:50):
But is almost impossible to see animals of
that size.
So when you see a five metergreat white, probably is going
to be the biggest you're goingto see in your life.
So to see a 5.5 meter greatwhite in so many years, so many
expeditions, that was very, verylucky.
And then here at the bottom wehave several teeth of extinct
(36:12):
great whites.
So that's, these are fossilteeth of great white.
Kate (36:16):
biggest one was from a Shark called Otodus Megalodon,
which literally means big tooth.
It was a type of mackerel Sharkthat existed from 23 million to
3 million years ago.
Alessandro (36:27):
Many people asked me, you're still alive, because
they saw kind of fakedocumentary that was aired on
Discovery Channel years ago,that was fake This animal has
gone extinct million years ago.
Recent studies say that he mayattain it up to 16 meters in
length, but the more recentstudy, again, say that maybe it
(36:48):
was up to 19 or 20 meters.
And also we have this section,we have ten signs about the
biology of sharks.
Just explain the basic factsabout their classification,
anatomy, feeding, reproduction,and then we have a specialized
library.
And there are more than 100books on sharks that I collected
(37:12):
in my activity.
Kate (37:13):
And how many books have you published?
Alessandro (37:16):
Here there is the section with my own books.
I published 20 books so far, allabout sharks.
And also there is a smallsection of the books uh, by
other authors to which Icontributed mostly with my
illustrations.
And uh, you know, I also wantedto show the people the actual
size of sharks.
But that's a small space.
So there was no way to have akind of a five meter great white
(37:39):
inside the space.
You know, then people will notbe able to even enter.
So I ask a local artist thatproduce this kind of
silhouettes, made in wood,showing the actual size of
different species of sharks thatwe can actually find in South
African water.
So you see, for example, thecommon thresher Shark, the
sandbar Shark, the cow Shark,the shortfin mako, the
(38:03):
Smooth-hound, the SouthernAfrican Frilled Shark, the Piked
dogfish.
Yeah, the Pygmy Shark and theThorny lanternshark.
These are two of the smallestsharks found in the world.
Kate (38:15):
Oh, wow.
They're six centimeters atbirth.
Alessandro (38:17):
Yeah.
So you see that.
These that you can see in thesesilhouettes are not the maximum
size of the species.
Because for example, the biggestone we have here is the Shortfin
Mako is 2.5 meters.
That's the size of sexualmaturity for all those species.
So the size when they becomesexually adult.
(38:37):
And the last thing, I had acouple of drawings of
illustrations in color made bypencil.
These were made by my father,Emilio de Maddalena years ago.
And this the, the biggest onethat was based on a photo took
by Valerie Taylor dangerous Reefin South Australia.
(38:58):
He, my father didn't knowanything about sharks.
He just copy the picture.
But the result to me is stillthe best drawing I've seen of a
Shark in my life.
So, just a way to remember myfather.
And the last thing I want tosay, that this small museum is
dedicated to Sauro Baldi that'sthe the Dad of my wife.
(39:19):
Because we built this spacetogether with my wife, biologist
Alessandra Baldi.
We thought it was a good idea todedicate the museum to him
because without his support, itwould be impossible to create
this space.
Kate (39:32):
Thank you so much for the tour and the interview and for
coming on the podcast,alessandro.
Alessandro (39:37):
It's my pleasure.
Thank you so much for theinvitation.
Kate (39:45):
Currently, the Shark museum is open for scheduled
lectures or an appointment onlywith Alessandro.
The lectures are in person, butin the future, Alessandro may
offer online options.
The lecture topics include dietand predatory tactics of sharks,
south African sharks, andethical pra ethical practices in
Shark cage diving.
(40:05):
He invites other Shark and oceanspecialists such as Professor
Mike Bruton and Wildlife Oceanphotographer Chris Fallows to
contribute their expertise aswell.
So folks don't get your Sharkinformation on social media.
As much as I feel threatened bysharks, I also feel a really
(40:25):
strong affinity for thesecreatures.
Sharks are a vital part of ourmarine ecosystems, and if we try
and change the balance of sharksor fish or other ocean
variables, we could be askingfor a disaster.
And just like Bruce, the Sharksays, in Finding Nemo fish are
friends, not food.
So let's think of sharks asfriends, and not foe, or any
(40:46):
other descriptive word thatstarts with the letter F.
Thanks for listening to Roadshowand Tell.
If you enjoyed this deep diveinto a specialty museum, make
sure you subscribe so you don'tmiss an episode.
We're a new podcast.
So if you wanna help support us,please share it with a friend
and leave a rating and review.
(41:08):
If you are involved with or knowof a regional or specialty
museum that should be featured,please get in touch at
roadshowandtell@gmail.com.
I'm your host, Kate.
Roadshow and Tell was edited andproduced on the lands of the
Gadigal people.
I acknowledge the TraditionalCustodians of the various lands
(41:29):
on which you may be listeningfrom, and the lands that the
museums featured in this podcastreside on.
I also acknowledge anyAboriginal or Torres Strait
Islander people listening tothis podcast.
I pay my respects to elderspast, present, and emerging, and
celebrate the diversity ofAboriginal peoples and their
ongoing cultures and connectionsto the lands And waters of
(41:52):
Australia.
Popular Podcasts
Las Culturistas with Matt Rogers and Bowen Yang
Ding dong! Join your culture consultants, Matt Rogers and Bowen Yang, on an unforgettable journey into the beating heart of CULTURE. Alongside sizzling special guests, they GET INTO the hottest pop-culture moments of the day and the formative cultural experiences that turned them into Culturistas. Produced by the Big Money Players Network and iHeartRadio.
Dateline NBC
Current and classic episodes, featuring compelling true-crime mysteries, powerful documentaries and in-depth investigations. Follow now to get the latest episodes of Dateline NBC completely free, or subscribe to Dateline Premium for ad-free listening and exclusive bonus content: DatelinePremium.com
24/7 News: The Latest
The latest news in 4 minutes updated every hour, every day.