
Something Strange Is Happening With These Leopard Sharks
Episode 2 | 13m 9sVideo has Closed Captions
Shark scientists head over to La Jolla to investigate a natural “shark spa.”
Shark scientists Jasmin Graham, A-bel Gong, and Andrew Nosal head over to La Jolla to investigate a natural “shark spa.” This unique part of the California coast is a favorite spot for leopard sharks and guitarfish. After studying them from afar, the team is heading out to check on the health of these elasmobranchs and see if they can gain insight into a new, strange behavior.
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Funding for SHARKS UNKNOWN WITH JASMIN GRAHAM is provided by the National Science Foundation.

Something Strange Is Happening With These Leopard Sharks
Episode 2 | 13m 9sVideo has Closed Captions
Shark scientists Jasmin Graham, A-bel Gong, and Andrew Nosal head over to La Jolla to investigate a natural “shark spa.” This unique part of the California coast is a favorite spot for leopard sharks and guitarfish. After studying them from afar, the team is heading out to check on the health of these elasmobranchs and see if they can gain insight into a new, strange behavior.
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Learn Moreabout PBS online sponsorshipI'm here in La Jolla Shores, meeting up with my friend and fellow shark scientist A-bel Gong and their mentor, Andy Nosal, A-bel studies sharks and rays in this area.
And Andy and Abel have noticed some interesting and unexplained behaviors here.
All right.
Ready to dive in?
Let’s do it.
Leopard sharks can grow anywhere from 3.9 to 6.2 feet.
They get their name from their unique spots, or as we call them, saddles from the front to the back of their bodies.
Female leopard sharks like to aggregate here.
And for a while, no one knew why.
Until A-bel's mentor, Andy Nosal, figured it out.
These leopard sharks are mostly pregnant females, and we think that they're incubating their developing embryos by hanging out in this warm water.
But what we discovered by tracking these pregnant females is that they kind of like flip.
And the whole point is to try to understand this behavior.
But we're not really sure because we just don't have enough information about that.
I'm joining them today to investigate this new mysterious leopard shark behavior.
But now there's an unexpected curveball in the mix.
The first tropical storm San Diego has seen in nearly 100 years.
Here in San Diego.
We got a hurricane and tropical storm warning.
Yeah, it's been super windy and it's an anomaly.
So Andy’s going to see what kind of sharks will find in these conditions.
And we'll see where the sharks are after the storm passes through.
Hey, Andy.
What's up?
So we're going to set up the drone today to take a look at the leopard sharks.
We've been doing near-daily surveys here.
Just to monitor of the population and look at some interesting behaviors.
But we were here 48 hours ago to see what the leopard sharks were like right before a tropical storm came through.
And there were a ton of sharks.
So now, now that the storm passed yesterday, we want to take a look and see what sharks look like today.
I'll be kind of shocked if there's any sharks.
Because the temperature of the water dropp ten degrees over the last 24 hours.
All right.
I think we're ready.
Oh this is very exciting.
I love watching I love watching drones, too.
There we go.
Goodbye.
Where are the sharks?
Any sharks?
Yeah there looks like a couple.
Oh there’s a lot of em.
Oh my gosh.
Wow.
Look there they are.
Wow they’re all right out there.
That’s so awesome.
So there's actually a canyon underwater.
And Andy was the one who kind of put the pieces all together as to why this canyon is so important for the sharks living in the area.
I like this map.
It's a bathymetry map and it shows us why that spot where the leopard sharks hang out is so special.
And you'll see that it's just inshore of the head of La Jolla Submarine Canyon.
Right.
So we can see these bathymetry lines getting very close together here.
That's telling us that it's very steep This is a very deep canyon.
It goes hundreds and hundreds of feet down.
And the reason that's important is as the waves approach the shoreline, the wave energy gets diverted away from the canyon head.
And so we tend to get big waves here and over here on either side of the sharks, but small waves here.
And so the calm water here means it's going to get warmer, right, because it's not mixing with the deeper, colder water.
I'm super excited.
They're super cute.
For my research, when I was in Andy's lab as a master's student at the University of San Diego, And we were basically looking to see where these shovelnose guitarfish and these bat rays were going.
And what we found is that they actually like to stay in the same spot as these leopard sharks, even though they are completely different species.
And actually a few years ago we caught a live footage on the drone of these two guitar fish that were doing a little mating dance.
They were circling around and it was so cool cause one was dark and one was light, and it literally looked like yin and yang.
Just circling around each other.
So we found that it supported this hypothesis that we have that, this might be also a mating ground.
So this area has a ton of different uses for sharks and rays.
So we'll take a look at some drone footage, and I'll show you how I track individual sharks Oh wow so it can see its exact body.
It does the outline of it.
That's right.
So we've just tracked one shark for about one minute and we do that 200 something more times and then we put everything together and then we can see all of the sharks being tracked at once to try to understand the sharks attracted to each other or are they just attracted to something favorable about that site?
Maybe it's a warm water patch and we can start to get at that by looking at all of their paths simultaneously.
Are they attracted to each other?
Are they repulsing from each other?
these are things that we're going to be looking at.
And every now and then you can see a flip that happens here.
Right now with like a head shake or a head jerk.
I'm not sure what to call it, but they kind of like wind up in one direction slowly and it's snap the other way.
Yeah, that just like maybe the head shake is also like a way to get rid of a parasite, right?
That “get off me.” Or that final like they were able dislodge it.
And then there's the final snap just, get it into the water And some days you see more flips than other days.
So it would be very interesting to try to understand why, why we see that variation.
It's a real big mystery, actually.
So we are going off of La Jolla to go see if we can catch some leopard sharks, see if there is some parasites on them.
And also see if they're still hanging around.
They were here yesterday post tropical storm, but who knows if they're hungry or if they'll be taking bait.
We hypothesize that the rolling behavior that we see from the drone footage is a means of dislodging ectoparasites.
We'll try to I.D.
them as best we can under a microscope.
But then we're also going to be extracting their DNA and sequencing some special barcoding genes that will tell us a little bit more precisely what kind of parasite it is.
So the calm water is good for today because the leopard sharks are usually very, very shallow just outside the surf zone, which means the boat has to get really close for us to be able to reach them with our lines.
This is very nice.
The calm after the storm, Oh, you see them on.
There they are.
They're there, they're there.
Oh got something.
One, two, three.
Let's take a look for parasites.
So really look at the gills.
Make sure there’s no little copepod tails sticking out.
Yeah, I'm not seeing anything.
There's not much.
They’re pretty clean, maybe because they're so good at rolling.
Note: No claspers.
Female shark.
Bye.
Bye-bye.
We’ve got another shark maybe.
Oh, it's a guitarfish.
Guitarfish!
Your favorite A-bel.
Yeah.
Guitarfish.
Okay.
Ready A-bel?
Coming at you?
Here we go.
Oh dammit.
Oh its a boy.
Oh, boy.
Oh, my God.
How cute.
Wait, this is the first time I get to see my study species in the wild.
Seriously?
Yeah!
These are claspers.
They are flimsy.
As they mature they calcify, so they get real stiff so you can't actually bend that.
My God, they're so cool.
See if there’s any parasites.
I don't see anything.
Since I did my master's thesis in, like, the middle of COVID, I didn't have a lot of chances to get into the field, go on a boat and check them out.
They're so cool in real life.
Another one.
Okay, now It’s a good day for fishing.
This one looks clean, too.
They're all clean.
One, two, three.
Okay, one last check for parasites.
Look in the armpits.
Got one.
Oh, right there.
You got it there.
Okay.
I’m ready to go.
Thanks for contributing to science.
Well, that was a pretty successful day.
We got several sharks.
We got a guitarfish We got a guitarfish, We got some parasites, a lot of sea lice.
So there seems to be a reason for them to maybe do that flipping behavior.
But we didn't find too many of them.
But maybe that's a sign that the rolling behavior is very effective at dislodging ectoparasites and trying to get them off before they get to firmly embedded.
So, I mean, first of all, it's so incredibly special that I got to see my study species in the wild for the first time.
So now to have this new sort of observation of, oh, there's a male here that is about to mature maybe further supports that this may be a mating ground and that male will come here more often, more frequently every summer.
These animals have just been like numbers and pictures for me.
So like to finally, like, see it.
I was like, You're real.
I learned a lot about myself while I was learning about sharks, too.
You know, as I was studying sharks, I began to kind of have this personal connection with them almost because of the way that I started seeing them and seeing a lot of myself in them, too, As a nonbinary trans person, you know, I feel like my identity has been really influenced by the way that media has portrayed nonbinary and trans people, and I feel like sharks have been kind of the same way, you know, with like Jaws and other big films that have sort of demonized sharks.
And so to see that sort of parallel with my identity has made me more motivated to study sharks and give them this sort of rewritten narrative.
It’s interesting that you say that because I feel the same way about sharks, and you know why I always root for the underdog and why I want people to see that sharks aren't evil or out to get them.
Just because the way that black people are portrayed in the media is “thugs, thieves” and I feel that people treat sharks in the same way that they see this negative representation in media and therefore they associate sharks with bad things.
I feel like both the black community and the trans community have sort of unfortunately, that aspect that they share in common.
And I just want to exist and I just want to be who I am and I'm sure sharks want the same thing too, but it's really taught me how to advocate for myself, because when I'm advocating for these misunderstood sharks, I am slowly building my own confidence to advocating for myself and being like I should be rooting for the underdog.
And sometimes the underdog is yourself and so studying sharks has just given me a lot of confidence to do that.
We're strong and we're here and we exist and we're not going away.
My mentorship has really helped me become a confident scientist
- Science and Nature
A series about fails in history that have resulted in major discoveries and inventions.
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Funding for SHARKS UNKNOWN WITH JASMIN GRAHAM is provided by the National Science Foundation.