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Weedy Seadragons -

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NARRATION

Researching creatures underwater is always subject to the vagaries of sea conditions. So it doesn't
always go swimmingly...

Ruben Meerman

We're about to head just out there, and with a bit of luck, we'll see some weedy seadragons. David
and his team have been working on them for about eight years and we're going to see what they get
up to underwater.

NARRATION

Hopefully this swell isn't making the water down below too murky.

Prof David Booth

It gets bigger, we've been in in slightly bigger, but any bigger than this we'd probably think
twice. The main thing is the surge down below, it should be alright.

NARRATION

Well the visibility in the water is down to a couple of metres at best. David can't conduct his
research in these conditions. So sadly we've decided to abandon this dive.

NARRATION

Fortunately David's had better luck on previous dive expeditions.

Prof David Booth

Well weedy seadragons, I've known about them for a long time and they're a very iconic fish.

Prof David Booth

And it's quite shocking to realise how little is known about them in their natural habitat. A few
bits of work had been done but even basic things like their growth rate, how long they live, how
far they move, was just completely unknown.

Ruben Meerman

So where does the weedy seadragon fit as a species, where does it sit?

Prof David Booth

There's two dragons. There's the weedy, the one we're studying, and also the leafy, an even more
bizarre looking creature. And there are the only species in their respective genera so there aren't
any similar species worldwide actually, so Australia,ah, we have them all.

Ruben Meerman

Fantastic, we're unique.

NARRATION

Seadragons, seahorses and pipe fish belong to the same family, so they share many intriguing
behaviours and physical attributes.

Prof David Booth

They have a long tubular snout, which they use to grab little prey items, little shrimps and
things. And they also have this curious habit of the males brooding the eggs. And in the case of
sea horses they brood them in a pouch, but in the case of seadragons the males have the eggs
attached to the outside of the tail.

NARRATION

So the men are left holding the babies.

Ruben Meerman

What is it that you're trying to establish with this study?

Prof David Booth

To understand how to manage any species in the wild we need some basic ecology. Basic what we call
population demography. We need to know how fast the animals grow, that can tell us information
about when they reproduce. We also need to know how long they live, seahorses maybe four to five
years and sea dragons six or seven years. So if the animals for whatever reason disappear from a
site, we know that it's going to take a long time for recovery of that site.

Ruben Meerman

So where did this guy come from?

Prof David Booth

This one was found deceased at the site at Kurnell.

Ruben Meerman

And so what's going on with the tagging system, how are you doing that?

Prof David Booth

Well this is probably a good way to illustrate how we tag.

Prof David Booth

We inject the animal with a small amount of this fluorescent elastomer under the skin. So with a
couple of different colours and several different locations we can get maybe two or three hundred
tag combinations so each fish has its own tag.

NARRATION

The non-toxic paint becomes highly visible under ultra-violet light.

Prof David Booth

We go down and shine the light on them and we know that's seadragon number 32 or whatever, and then
we just survey repeatedly over the years.

Ruben Meerman

So what have you found so far about their lives?

Prof David Booth

Well for a fish the size they are they don't move very much. And interesting, a lot of large fish
don't move very far. It's the babies that move. And so typically with these guys, they might move
about 100 metres or so in their adult lives.

NARRATION

Seadragons are quite a widespread species. They're distributed from north of Sydney all the way
around the south coast into Western Australia. On most reefs that are suitable you'll find a few
seadragons.

Prof David Booth

We've noticed through the years some of the sites there's been a bit of a decline in numbers. It's
hard even if you're working on a species for six or seven years, it's hard to really put your
finger on whether this is a global decline or whatever. We're going to keep an eye on them.

Prof David Booth

I think it's more a habitat thing. Botany Bay is a very urbanised bay. But the mouth of Botany Bay
is in pretty reasonable shape. There's all sorts of potential threats with development that we've
got to keep an eye on, but provided we can keep those kelp beds in reasonable condition, I think
the seadragons will benefit and thrive.

NARRATION

So, with a bit of luck, the next time David and his crew venture down into the world of the
seadragons, the water conditions will be more favourable. We've still got a lot to learn about
these surprising sea creatures.

Story Contacts

Professor David Booth

University of Technology, Sydney

Dept of Environmental Sciences

Building 4, Level 5, Room 5.45B

Jaime Sánchez-Cßmara (underwater archive footage)

Aquadec Aquariums S.L.

Pol. Ind. El Vadillo. C/ Santo Domingo s/n

18600 Motril, Granada, Spain

Related Info

Sydney Institute of Marine Science (SIMS): Weedy Seadragons

Australian Museum - Weedy Seadragon

Australian Museum - Leafy Seadragon