1
00:00:02,000 --> 00:00:07,000
Downloaded from
YTS.MX
2
00:00:02,480 --> 00:00:05,040
In a remote corner of Australia...
3
00:00:05,040 --> 00:00:06,320
Oh no!
4
00:00:06,960 --> 00:00:09,680
...a group of bull sharks
is targeting sports fishermen
5
00:00:08,000 --> 00:00:13,000
Official YIFY movies site:
YTS.MX
6
00:00:09,680 --> 00:00:11,800
with unprecedented ferocity.
7
00:00:12,320 --> 00:00:13,760
Holy ****!
8
00:00:15,040 --> 00:00:18,160
Showing evidence of
a sophisticated new hunting behavior.
9
00:00:19,920 --> 00:00:22,840
- You need to hook 10-15 fish...
Oh, look out!
10
00:00:23,320 --> 00:00:24,440
...just to get one to the boat.
11
00:00:26,360 --> 00:00:30,200
Now, a research team
is launching an ambitious investigation
12
00:00:32,360 --> 00:00:33,800
using ground-breaking technology...
13
00:00:34,440 --> 00:00:36,560
Oh, he's got it! How good was that?
14
00:00:36,560 --> 00:00:39,920
...to find out if one of the
world's most dangerous sharks...
15
00:00:39,920 --> 00:00:42,160
Oh, there it is!
Ah! Look at the size of it!
16
00:00:42,840 --> 00:00:44,440
... just got smarter.
17
00:00:53,280 --> 00:00:58,280
{\an8}Weipa, a remote mining town located
on the edge of northeastern Australia.
18
00:01:00,400 --> 00:01:01,320
Each year,
19
00:01:01,320 --> 00:01:05,480
hundreds of sports fishermen are drawn to
its shores by seasonal fish migrations.
20
00:01:07,120 --> 00:01:08,000
But more and more,
21
00:01:08,240 --> 00:01:12,080
their catch is being stolen
in audacious underwater raids.
22
00:01:13,080 --> 00:01:15,640
Some fishermen even claim
the sharks have learned
23
00:01:15,640 --> 00:01:19,320
how to recognize
and follow individual boats.
24
00:01:21,920 --> 00:01:25,000
Shark biologists Dr. Johan Gustafson
25
00:01:25,000 --> 00:01:28,920
and Dr. Mariel Familiar Lopez
are here to investigate.
26
00:01:30,160 --> 00:01:33,360
What's actually happening here
is a behavior called depredation
27
00:01:34,640 --> 00:01:37,360
and that's when a fisherman's
caught a fish and they're winding it in
28
00:01:37,360 --> 00:01:38,920
and then a shark will come
and take that fish.
29
00:01:40,360 --> 00:01:45,080
Locals claim they are losing as
much as 80% of their catch to the sharks.
30
00:01:46,800 --> 00:01:49,400
The level of depredation
described by the fishermen
31
00:01:49,400 --> 00:01:52,800
hasn't been seen anywhere else
in Australia or even the world.
32
00:01:55,800 --> 00:01:58,400
Johan and Mariel
have timed their arrival
33
00:01:58,400 --> 00:02:00,560
with the height
of the tuna fishing season.
34
00:02:01,840 --> 00:02:03,400
{\an8}But with a weather front moving in,
35
00:02:03,680 --> 00:02:07,920
{\an8}they have just 10 days until strong
winds whip up a powerful swell
36
00:02:09,640 --> 00:02:12,440
and force their research
vessel back to port.
37
00:02:13,560 --> 00:02:16,320
We have a variety of equipment
we're going to utilize.
38
00:02:16,320 --> 00:02:19,960
We've got acoustic tags, cameras,
39
00:02:20,480 --> 00:02:23,680
and for the first time ever,
a new cage design.
40
00:02:24,760 --> 00:02:27,120
If what the fisherman are saying is true,
41
00:02:28,880 --> 00:02:29,960
I want to know why.
42
00:02:34,240 --> 00:02:38,240
Johan and Mariel team
up with local fisherman, Wade Alleyn.
43
00:02:38,760 --> 00:02:42,280
Together, they're heading
to one of his favorite fishing spots.
44
00:02:43,400 --> 00:02:46,400
What's your experience
with the sharks versus the anglers?
45
00:02:46,840 --> 00:02:50,080
Definitely have an
issue with the bull sharks.
46
00:02:50,800 --> 00:02:55,480
I believe they've definitely tuned in on
the boats. They relate the boats to food.
47
00:02:57,000 --> 00:03:01,160
Bull sharks are often depicted
as mindless, opportunistic killers.
48
00:03:02,000 --> 00:03:04,680
But they're armed with an array
of high-performance senses
49
00:03:04,680 --> 00:03:07,600
they could be using
to target the fishermen.
50
00:03:08,040 --> 00:03:11,120
Smell many times
more powerful than humans.
51
00:03:12,280 --> 00:03:15,120
Vision that pierces
through the murkiest waters.
52
00:03:16,080 --> 00:03:20,120
And hearing that can pick up
sound from over a mile away.
53
00:03:21,280 --> 00:03:24,800
Do you think they're mainly bull sharks,
the ones that are taking the fish?
54
00:03:24,800 --> 00:03:27,240
I mean, it's hard for us
to identify all the time
55
00:03:27,640 --> 00:03:29,360
because they'll eat our fish out of sight.
56
00:03:29,360 --> 00:03:32,200
But there are definitely
a lot of bull sharks down here.
57
00:03:34,520 --> 00:03:36,040
To find out for sure,
58
00:03:36,040 --> 00:03:40,200
and see if the situation in Weipa
is as bad as the fishermen claim,
59
00:03:40,440 --> 00:03:43,760
Johan and Mariel
go fishing for themselves.
60
00:03:44,680 --> 00:03:48,680
We're using a fishing line
camera to be able to ID the shark.
61
00:03:50,280 --> 00:03:51,240
Is it a bull shark?
62
00:03:51,240 --> 00:03:54,120
Also, we're going to be able
to see a bit more information
63
00:03:54,120 --> 00:03:57,760
about the behavior that's occurring.
When does the shark come in?
64
00:03:58,440 --> 00:04:00,600
There we go. Let's get it in the water.
65
00:04:05,000 --> 00:04:06,840
Right, we'll send this
all the way to the bottom.
66
00:04:14,560 --> 00:04:15,640
How's my technique, Wade?
67
00:04:16,080 --> 00:04:18,360
Spot on, mate.
I couldn't do it better myself.
68
00:04:22,440 --> 00:04:28,080
Yep, yeah. (grunts) Oh!
Oh, it's a fish! I got a fish!
69
00:04:32,040 --> 00:04:33,200
It's taking it down.
70
00:04:37,200 --> 00:04:39,760
Alright, I'll try
and bring it up.
71
00:04:40,480 --> 00:04:43,160
Oh, it's gone!
72
00:04:45,640 --> 00:04:49,000
You got bitten off!
Yep. I think we got sharked.
73
00:04:50,200 --> 00:04:52,440
Within moments of snaring a fish,
74
00:04:52,720 --> 00:04:57,160
Johan's catch is stolen by an
unmistakable underwater raider,
75
00:04:58,920 --> 00:05:00,400
a bull shark.
76
00:05:01,320 --> 00:05:05,160
Wow. That's a big shark.
Over three, three and a half meters.
77
00:05:06,320 --> 00:05:08,960
The fishing line camera did a great job.
78
00:05:09,200 --> 00:05:11,480
Alright? We were able
to confirm the species
79
00:05:11,480 --> 00:05:15,960
and the first fish we caught,
it was taken by a shark in 20 seconds.
80
00:05:17,160 --> 00:05:19,680
That gives more weight to what
the fishermen are claiming up here.
81
00:05:21,760 --> 00:05:25,480
This is the first time I've been able to
actually capture a depredation event
82
00:05:26,120 --> 00:05:29,080
so close-up, underwater. This is amazing.
83
00:05:30,280 --> 00:05:32,680
Yeah. It is really amazing footage.
84
00:05:34,000 --> 00:05:37,320
Now we've seen one shark under
the water from the view of a camera.
85
00:05:38,200 --> 00:05:41,680
We want to see more. We want to
see are there other sharks around?
86
00:05:41,680 --> 00:05:43,880
So we need to get in the water with them.
87
00:05:48,840 --> 00:05:52,720
In a place as remote as Weipa,
that's a significant challenge.
88
00:05:54,080 --> 00:05:57,760
You need to remember, we're diving in an
area where sharks have never seen a cage.
89
00:05:58,360 --> 00:06:00,720
Sharks have
an acute sense of hearing.
90
00:06:01,160 --> 00:06:06,360
They use it to locate their prey,
but also keep themselves out of danger.
91
00:06:07,600 --> 00:06:10,880
Loud, unfamiliar noises
can put them on edge.
92
00:06:14,400 --> 00:06:17,640
Sound is an important
thing in an aquatic environment
93
00:06:19,000 --> 00:06:22,400
because it travels four
times faster than in air.
94
00:06:23,440 --> 00:06:28,040
The thing with sharks is loud,
sudden, sharp noises tend to spook them.
95
00:06:28,720 --> 00:06:31,960
The team has come
prepared with a radical prototype
96
00:06:32,280 --> 00:06:36,080
designed and built by underwater
cinematographer Colin Thrupp.
97
00:06:36,840 --> 00:06:40,880
A noise canceling cage
made entirely of plastic.
98
00:06:41,680 --> 00:06:43,840
So how do we reckon this is
going to go when we get in the water?
99
00:06:43,840 --> 00:06:45,640
Do you reckon these joins
are going to hold?
100
00:06:46,320 --> 00:06:51,200
I mean, a cage made out
of polyethylene pipe
101
00:06:51,200 --> 00:06:54,720
sounds a bit nuts
when you first talk about it,
102
00:06:54,720 --> 00:06:58,000
but when you actually get these
things together, it's pretty strong.
103
00:06:59,000 --> 00:07:01,880
A world-first,
the cage has been forged
104
00:07:01,880 --> 00:07:04,320
using cutting edge electro-fusion welding,
105
00:07:04,680 --> 00:07:07,080
a technique that bonds plastic
by super-heating it
106
00:07:07,640 --> 00:07:10,080
to over 200 degrees Fahrenheit.
107
00:07:11,160 --> 00:07:16,240
I've been told that an earth mover
can hit this and then bounce off.
108
00:07:16,240 --> 00:07:17,120
Okay.
109
00:07:17,120 --> 00:07:19,640
But I haven't heard what
happens if a bull shark hits it.
110
00:07:20,000 --> 00:07:21,800
Well we'll test it.
- That's what we're here to do.
111
00:07:21,800 --> 00:07:23,080
We're here to test it. We'll see.
112
00:07:27,760 --> 00:07:29,600
What I'm hoping
is that these sharks
113
00:07:29,600 --> 00:07:32,360
become more accustomed
to this plastic cage,
114
00:07:32,360 --> 00:07:34,720
which is quieter and a
little bit more stealthy.
115
00:07:35,520 --> 00:07:39,200
It's going to minimize the noise
and hopefully get us closer to the sharks.
116
00:07:41,440 --> 00:07:45,520
If the plastic cage works
and sharks do come closer,
117
00:07:45,520 --> 00:07:48,840
this could be a game-changer
of how we study shark behavior,
118
00:07:48,840 --> 00:07:51,720
not just up here at Weipa
but around the world.
119
00:07:53,840 --> 00:07:58,760
Topside, topside.
Please begin lowering the cage.
120
00:08:00,160 --> 00:08:03,080
Monitoring the descent
of the experimental cage
121
00:08:03,560 --> 00:08:05,640
is divemaster, Che McGuiness.
122
00:08:06,960 --> 00:08:10,400
So, can you give us
an indication of the cage?
123
00:08:12,440 --> 00:08:15,320
JOHAN
The cage is sitting fine, over.
124
00:08:18,520 --> 00:08:20,760
On the surface, Wade casts out.
125
00:08:22,160 --> 00:08:24,880
The water visibility is unseasonably poor
126
00:08:25,680 --> 00:08:30,280
but his on-board sonar reveals
there are big animals lurking below.
127
00:08:33,200 --> 00:08:36,560
COLIN
I have a big bull shark, 10 meters out.
128
00:08:39,040 --> 00:08:42,000
They're staying right
on the edge of our periphery.
129
00:08:45,400 --> 00:08:47,160
We can only just see them.
130
00:08:51,360 --> 00:08:52,960
The sharks move in closer,
131
00:08:55,640 --> 00:08:57,520
and there's more than expected.
132
00:08:58,560 --> 00:09:02,280
There's at
least six, maybe seven bull sharks
133
00:09:02,280 --> 00:09:06,120
directly beneath us
right on the edge of the murk.
134
00:09:09,760 --> 00:09:13,720
They're not sure what
we are. They're keeping a safe distance.
135
00:09:16,360 --> 00:09:19,240
Encountering this big pack of bull sharks
136
00:09:19,480 --> 00:09:23,920
is the first clue something different
is happening in the waters around Weipa.
137
00:09:25,080 --> 00:09:27,280
A lot of the times I've
seen them just by themselves.
138
00:09:27,520 --> 00:09:30,320
But here I'm seeing a group
of bull sharks together.
139
00:09:31,520 --> 00:09:35,160
Bull sharks are normally
solitary and fiercely territorial.
140
00:09:35,800 --> 00:09:37,960
They're even known to be cannibalistic.
141
00:09:39,360 --> 00:09:41,560
Do these sharks
hang out here all the time?
142
00:09:42,000 --> 00:09:46,240
Do they hang out together all the time?
What's the pecking order in this group?
143
00:09:47,320 --> 00:09:49,320
We have a lot of work ahead of us
to answer these questions.
144
00:09:51,800 --> 00:09:52,840
COLIN
This is great!
145
00:09:54,160 --> 00:09:58,200
All we need now
is for Wade to get a fish on his line.
146
00:10:02,200 --> 00:10:04,560
Divers, divers. Just letting you know.
147
00:10:04,560 --> 00:10:08,680
The swell and wind has increased
swell and wind has increased.
148
00:10:09,280 --> 00:10:12,720
If it becomes unsafe or
unworkable, let us know. Over.
149
00:10:14,680 --> 00:10:18,240
Another challenge the team
must deal with has reared its head.
150
00:10:19,000 --> 00:10:22,000
JOHAN
Copy that. Let's just see how we go.
151
00:10:24,160 --> 00:10:28,040
This year, the whole of
Australia is suffering from La Niña,
152
00:10:29,680 --> 00:10:32,920
an atmospheric phenomenon
that plays havoc with the weather.
153
00:10:34,040 --> 00:10:39,960
Recent rainwater has been pouring out of
nearby rivers, reducing ocean visibility.
154
00:10:41,800 --> 00:10:43,960
Whilst unpredictable winds on the surface
155
00:10:44,600 --> 00:10:47,200
are churning up
the coastal currents below.
156
00:10:49,040 --> 00:10:52,840
Johan. Johan. Does the cage feel steady?
157
00:10:54,920 --> 00:10:56,960
JOHAN
The cage is bouncing a lot.
158
00:10:59,000 --> 00:11:01,200
We are concerned
because this is a plastic cage.
159
00:11:01,200 --> 00:11:05,080
It hasn't been really used a lot of times,
and we haven't really tested it that much.
160
00:11:06,760 --> 00:11:08,200
The lightweight plastic cage
161
00:11:08,200 --> 00:11:10,920
is being pushed and pulled
by the turbulent water.
162
00:11:12,680 --> 00:11:14,880
If the ropes connecting it
to the boat snap,
163
00:11:15,840 --> 00:11:19,640
Colin and Johan could be swimming
unprotected from the sharks.
164
00:11:25,040 --> 00:11:26,360
Johan, Johan, copy?
165
00:11:29,520 --> 00:11:32,560
Johan, Johan, Johan, do you copy? Over.
166
00:11:43,000 --> 00:11:46,160
JOHAN
Topside, topside can you hear me?
167
00:11:47,280 --> 00:11:50,200
I can hear you now.
I can hear you now.
168
00:11:51,960 --> 00:11:53,400
The current's getting stronger.
169
00:11:55,360 --> 00:11:57,760
Tipping the experimental cage on its side.
170
00:11:59,280 --> 00:12:02,200
Has the cage stabilized, over?
171
00:12:06,160 --> 00:12:08,080
COLIN
The cage is buckling under the pressure.
172
00:12:09,320 --> 00:12:11,200
You need to get us up now, over.
173
00:12:13,840 --> 00:12:16,320
Coming up now. Coming up now. Over.
174
00:12:17,400 --> 00:12:18,200
COLIN
Copy that.
175
00:12:28,840 --> 00:12:31,680
We got you at the surface.
Just wait there for a second.
176
00:12:32,080 --> 00:12:36,840
Safely alongside the
mothership the damage becomes clear.
177
00:12:40,160 --> 00:12:42,560
We had raging current
by the end of that,
178
00:12:42,560 --> 00:12:46,120
you could just see this
thick plume of just muck
179
00:12:46,240 --> 00:12:49,120
just come through and sweep
us and really tip the cage.
180
00:12:49,360 --> 00:12:52,840
The plastic cage didn't like it at all
it was really bowing under that pressure.
181
00:12:54,480 --> 00:12:56,360
We were getting a
little bit banged up underwater,
182
00:12:56,880 --> 00:13:00,400
but the plastic cage did do
what it was supposed to do.
183
00:13:00,680 --> 00:13:04,760
We did get close to those sharks,
and they did seem to not be spooked by us.
184
00:13:05,400 --> 00:13:08,800
I think we had around six to
ten sharks at any one time
185
00:13:09,080 --> 00:13:12,000
swimming around us up nice and
close. We could almost touch them.
186
00:13:13,800 --> 00:13:18,080
Johan and Mariel still need
to observe sharks raiding the fishermen
187
00:13:18,080 --> 00:13:19,080
from underwater.
188
00:13:20,320 --> 00:13:24,480
But it will take several days for the
cage to be repaired and strengthened.
189
00:13:24,640 --> 00:13:25,640
Yep! Grounded.
190
00:13:28,280 --> 00:13:31,080
It gives them time to
investigate a different question.
191
00:13:33,520 --> 00:13:34,640
According to the fishermen,
192
00:13:35,640 --> 00:13:38,880
it's the noise of their vessels
or the shape of their vessels
193
00:13:38,880 --> 00:13:40,880
that's attracting sharks
to these fishing grounds.
194
00:13:41,360 --> 00:13:44,520
Some locals claim
an even more radical sea-change,
195
00:13:45,360 --> 00:13:46,840
that the bull sharks have learned
196
00:13:46,840 --> 00:13:50,800
how to distinguish and follow
individual fishing boats.
197
00:13:54,320 --> 00:13:56,920
Johan and I have
devised a little experiment
198
00:13:57,200 --> 00:14:00,520
to see if we can prove or disprove
what the fishermen are telling us.
199
00:14:00,520 --> 00:14:02,600
Are the sharks really
following their boats?
200
00:14:07,280 --> 00:14:09,840
To find out how shrewd the sharks are,
201
00:14:10,120 --> 00:14:13,000
they need to be tagged
with acoustic transmitters.
202
00:14:13,280 --> 00:14:14,760
These will monitor their movements.
203
00:14:15,400 --> 00:14:19,320
But to fit them, the sharks must
be brought alongside the boat.
204
00:14:20,720 --> 00:14:24,640
In my experience, rod and reel has
always been the best option just for us,
205
00:14:24,640 --> 00:14:26,800
but also for the welfare of the shark.
206
00:14:28,120 --> 00:14:31,680
We're there the whole time with it.
We can bring it in quickly.
207
00:14:31,680 --> 00:14:34,680
We can handle it faster
and we can release it faster.
208
00:14:37,000 --> 00:14:38,640
Johan straps in.
209
00:14:39,240 --> 00:14:43,840
Landing a shark means going head-to-head
against its power and strength.
210
00:14:56,240 --> 00:15:02,800
Oh, were on! Were on!
Yep, we got one!
211
00:15:03,920 --> 00:15:08,480
It's a fair bit of weight.
That's a decent shark.
212
00:15:08,480 --> 00:15:11,240
You can feel a strong head movement.
213
00:15:12,920 --> 00:15:15,320
Oh! We are gaining ground, boy!
214
00:15:15,880 --> 00:15:18,360
Once we get the
shark up close to the boat,
215
00:15:18,360 --> 00:15:22,760
we're going to be putting in
a head rope and then a tail rope
216
00:15:22,760 --> 00:15:24,840
and then we're going
to flip it upside down.
217
00:15:24,840 --> 00:15:28,360
So, belly up, to try to put
him in tonic immobility.
218
00:15:29,640 --> 00:15:33,160
To roll the shark over, the
team need to bring it closer to the boat
219
00:15:33,440 --> 00:15:36,080
and maneuver it with a rope
attached to its tail.
220
00:15:40,160 --> 00:15:43,560
It's definitely a bull.
Oh, it's a female.
221
00:15:47,520 --> 00:15:49,040
She's feisty.
She's feisty.
222
00:15:55,000 --> 00:15:57,160
Tail rope is on.
Good work!
223
00:15:58,800 --> 00:16:01,200
It's upside down,
and she's getting calmer.
224
00:16:02,400 --> 00:16:05,760
Tonic immobility is when
a shark is put belly up.
225
00:16:06,480 --> 00:16:08,840
Basically, they go into
a transient sleep state.
226
00:16:09,560 --> 00:16:11,440
They're not completely asleep or unaware.
227
00:16:12,000 --> 00:16:14,560
They can snap out of this,
so we have to be quite cautious still.
228
00:16:15,640 --> 00:16:17,000
The quicker the team works,
229
00:16:17,120 --> 00:16:19,920
the better it will be
for both them and the shark.
230
00:16:20,600 --> 00:16:22,800
First up, the acoustic tag.
231
00:16:24,040 --> 00:16:26,000
It'll allow us to map
the movement patterns
232
00:16:26,000 --> 00:16:28,040
and behaviors of bull sharks in this area,
233
00:16:28,040 --> 00:16:30,680
and it's extremely pivotal
to this experiment.
234
00:16:31,640 --> 00:16:33,400
Okay. Tag is on.
235
00:16:36,800 --> 00:16:38,720
Measuring in at over eight feet,
236
00:16:40,200 --> 00:16:42,280
this bull shark is a prize catch.
237
00:16:43,520 --> 00:16:46,680
The decision is taken to fit
an additional fin camera.
238
00:16:48,160 --> 00:16:51,000
It can tell us so much
about that shark's behavior.
239
00:16:51,240 --> 00:16:53,200
How fast is a shark swimming?
240
00:16:53,200 --> 00:16:57,040
Are they swimming really close to the
surface or are they going really deep?
241
00:16:58,480 --> 00:17:01,880
This treasure trove of data
will pop off the shark automatically
242
00:17:01,880 --> 00:17:03,040
in a few days.
243
00:17:03,800 --> 00:17:05,840
It's time to release the hook.
244
00:17:06,280 --> 00:17:10,040
Alright, let's get rid
of this thing. Yep, off.
245
00:17:13,240 --> 00:17:14,200
Let her free?
Let it go.
246
00:17:14,200 --> 00:17:16,200
Let it go.
Woo-woo!
247
00:17:17,040 --> 00:17:18,800
Perfect. Good release, guys.
248
00:17:21,240 --> 00:17:23,360
Before they run their experiment,
249
00:17:23,360 --> 00:17:27,440
Johan and Mariel need to fit
as many acoustic tags as possible.
250
00:17:32,120 --> 00:17:36,040
Working like a well-oiled machine,
and with the sharks' welfare in mind,
251
00:17:36,040 --> 00:17:40,000
they catch and swiftly release
four more bull sharks.
252
00:17:40,160 --> 00:17:40,960
Done!
253
00:17:43,040 --> 00:17:44,400
All these tags that we're putting
254
00:17:44,400 --> 00:17:47,000
is getting us closer to an answer
of what's going on here.
255
00:17:50,240 --> 00:17:52,560
We're going to give
them 24 hours to relax
256
00:17:52,560 --> 00:17:56,480
and go back to a more natural behavior
before we start our experiments.
257
00:18:04,680 --> 00:18:08,080
The tagging experiment
is designed to prove or disprove
258
00:18:08,080 --> 00:18:11,520
the fishermen's claims that sharks
are following their fishing boats.
259
00:18:12,920 --> 00:18:15,440
Johan and Mariel
split up into two boats
260
00:18:15,440 --> 00:18:17,840
and both deploy hydrophone receivers.
261
00:18:20,720 --> 00:18:22,880
We can detect the pings
that are coming off those tags.
262
00:18:27,840 --> 00:18:30,760
Two of the sharks
they tagged are quickly located,
263
00:18:30,760 --> 00:18:33,880
still lurking together
in the same fishing spot.
264
00:18:34,680 --> 00:18:37,160
Yes Johan.
I've got two of our tagged sharks here.
265
00:18:37,160 --> 00:18:38,040
How about you?
266
00:18:38,440 --> 00:18:40,800
Uh, hold on.
We're going to come to you. Over.
267
00:18:42,520 --> 00:18:44,240
The experiment can begin.
268
00:18:45,960 --> 00:18:51,000
Johan is in Wade's fishing boat. He'll
cast out to get the sharks attention.
269
00:18:51,680 --> 00:18:53,800
Once they're stealing fish off his line,
270
00:18:54,200 --> 00:18:57,400
the fishing boat will move
several miles down the coast.
271
00:18:58,280 --> 00:19:02,680
Mariel will track the tagged sharks from
the second boat to see if they follow.
272
00:19:04,200 --> 00:19:06,440
Johan is going to start
fishing from the other boat
273
00:19:07,040 --> 00:19:09,120
and he's going to wait
for a depredation event.
274
00:19:22,240 --> 00:19:23,320
Yeah. We're hooked up.
275
00:19:26,440 --> 00:19:27,560
Wow. That's a good-size one.
276
00:19:40,800 --> 00:19:43,280
Oh. No, no, I'm getting
shut. No, that's changed.
277
00:19:43,280 --> 00:19:47,080
I think that's a shark.
That's a shark. Oh!
278
00:19:56,800 --> 00:20:00,200
Oh! Oh, no. It's off.
279
00:20:00,200 --> 00:20:05,440
Mariel, Mariel? Got bitten
off by a shark. So, it is happening here.
280
00:20:06,320 --> 00:20:08,600
I still got our two tagged sharks here.
281
00:20:09,600 --> 00:20:11,800
Okay.
Let's pack up everything here.
282
00:20:11,800 --> 00:20:15,880
We're going to move down to the other site
and we're going to see they follow. Okay?
283
00:20:16,440 --> 00:20:17,360
MARIEL
Roger that.
284
00:20:20,720 --> 00:20:21,920
The big question is:
285
00:20:24,960 --> 00:20:26,760
have the sharks followed?
286
00:20:30,040 --> 00:20:31,520
MARIEL
Johan, Johan, do you copy?
287
00:20:32,960 --> 00:20:34,080
Yes, I read you.
288
00:20:34,560 --> 00:20:38,320
I don't pick up any
tagged sharks over here. Over.
289
00:20:40,160 --> 00:20:42,600
Well look,
we've been here for 30 minutes now.
290
00:20:43,200 --> 00:20:46,160
I think that if they were
following us from there,
291
00:20:46,160 --> 00:20:48,360
we would have picked them up
on the hydrophone by now.
292
00:20:49,400 --> 00:20:54,480
That's a result for us. It means they
haven't followed us from that site.
293
00:20:55,600 --> 00:20:58,440
The tagged bull
sharks are nowhere to be seen.
294
00:20:59,240 --> 00:21:01,720
But at this new site.
even without fishing,
295
00:21:02,520 --> 00:21:07,600
the on-board sonar reveals a school
of different sharks lining up below.
296
00:21:09,600 --> 00:21:10,800
That's a shark there.
297
00:21:12,760 --> 00:21:14,920
That is interesting.
What does this mean?
298
00:21:16,640 --> 00:21:19,680
The experiment
has delivered an unexpected result.
299
00:21:22,320 --> 00:21:25,360
We don't think that
sharks are following the boats.
300
00:21:26,480 --> 00:21:31,560
What's more likely is this depredation
behavior is much more widespread
301
00:21:31,800 --> 00:21:34,800
in the population of bull sharks
up here at Weipa.
302
00:21:37,720 --> 00:21:40,560
Rather than being
followed by specific sharks,
303
00:21:40,560 --> 00:21:45,640
all the bull sharks in the region may have
learned how to carry out these raids
304
00:21:45,800 --> 00:21:49,400
and could be ambushing the
fishermen wherever they go.
305
00:21:50,960 --> 00:21:54,440
We need to remember that this
was just one small experiment
306
00:21:54,440 --> 00:21:55,920
with only a few tagged sharks.
307
00:21:56,760 --> 00:22:01,040
But what it does indicate is that the
scale of these depredation behaviors
308
00:22:01,040 --> 00:22:05,560
could be occurring far more widespread and
intense than what the fishermen realize.
309
00:22:06,400 --> 00:22:10,600
It could explain why such
a huge proportion of the fishermen's catch
310
00:22:10,600 --> 00:22:11,520
is being taken.
311
00:22:11,960 --> 00:22:14,960
But why do so many bull
sharks in these waters
312
00:22:15,160 --> 00:22:17,440
appear to be conducting these raids?
313
00:22:19,920 --> 00:22:23,760
Forces beyond Weipa's shores
are likely playing a role.
314
00:22:25,040 --> 00:22:30,400
Australian fish stocks have decreased
by 31% over the past decade.
315
00:22:31,160 --> 00:22:34,360
Scientists believe this pressure
could be forcing sharks
316
00:22:34,360 --> 00:22:36,680
to alter their natural hunting behavior.
317
00:22:37,800 --> 00:22:40,880
But it still leaves
many questions unanswered.
318
00:22:42,320 --> 00:22:46,360
We want to know,
why is it so concentrated here in Weipa?
319
00:22:49,560 --> 00:22:52,480
Now halfway through
their time in northern Australia,
320
00:22:52,480 --> 00:22:57,760
the team has just five days until strong
winds will force them back to port.
321
00:22:58,760 --> 00:23:01,800
Colin has fixed and strengthened
the plastic cage.
322
00:23:01,800 --> 00:23:05,320
It's ready for him and Johan
to go back in the water.
323
00:23:07,200 --> 00:23:11,760
So far we've only seen the depredation
behavior from the fishing-line camera.
324
00:23:11,960 --> 00:23:15,120
But what we want to do
is see it from the plastic cage
325
00:23:15,120 --> 00:23:17,040
and that's the intention of this dive.
326
00:23:17,760 --> 00:23:19,720
We know that there is
multiple sharks down there.
327
00:23:20,680 --> 00:23:24,800
Wade's up top. He's going to be fishing,
and hopefully we'll be able to see,
328
00:23:24,800 --> 00:23:27,680
is there a hierarchy
between different sized sharks?
329
00:23:28,600 --> 00:23:30,160
What's the etiquette at this dinner table?
330
00:23:32,840 --> 00:23:37,240
On this dive, a 360-degree
drop camera will help fight back
331
00:23:37,400 --> 00:23:39,920
against the unpredictable
water visibility.
332
00:23:41,240 --> 00:23:44,120
We're really hoping to get
a lot of information from it.
333
00:23:50,760 --> 00:23:52,840
The cage is lowered into position.
334
00:23:57,120 --> 00:24:03,560
On the surface, Wade casts out.
Shadows emerge deep in the water.
335
00:24:05,280 --> 00:24:06,880
JOHAN
I've got two bull sharks.
336
00:24:06,880 --> 00:24:12,440
Two bull sharks. Approximately
five meters below us. Over.
337
00:24:14,000 --> 00:24:16,000
COLIN
The sharks are coming in closer.
338
00:24:18,440 --> 00:24:19,920
They're getting more confident with us.
339
00:24:22,600 --> 00:24:25,040
We've got three
bull sharks around us now.
340
00:24:28,880 --> 00:24:31,520
Topside, Wade has a fish on.
341
00:24:35,800 --> 00:24:37,080
JOHAN
They're just circling.
342
00:24:38,120 --> 00:24:41,040
COLIN
Not coming in too close to take the fish.
343
00:24:44,680 --> 00:24:47,040
The sharks are biding their time.
344
00:24:47,560 --> 00:24:51,760
But as the fish on Wade's
line tires, they strike.
345
00:24:52,360 --> 00:24:53,840
JOHAN
Big bull coming up, big bull.
346
00:24:57,240 --> 00:24:59,800
Here he comes. He's going for the fish.
347
00:25:16,960 --> 00:25:20,120
COLIN
Oh! He's got it! How good was that!
348
00:25:20,800 --> 00:25:23,800
We were expecting to see
the shark come really fast
349
00:25:23,800 --> 00:25:27,200
and just snap it from the line.
But that's not what we saw.
350
00:25:28,560 --> 00:25:31,800
It came in slow.
No sense of urgency at all
351
00:25:32,080 --> 00:25:35,080
and just basically plucked
the fish off the hook.
352
00:25:36,920 --> 00:25:39,360
I've never seen that before.
It was incredible.
353
00:25:40,680 --> 00:25:44,560
Another thing I noticed
was the biting tactic.
354
00:25:44,800 --> 00:25:48,120
So, the sharks took out
the propeller of the fish.
355
00:25:48,280 --> 00:25:50,120
It bit off the tail section first.
356
00:25:50,360 --> 00:25:55,280
And then they came swooping around again,
slow and calm, and they took out the rest.
357
00:25:57,600 --> 00:25:59,320
The general perception about bull sharks
358
00:25:59,320 --> 00:26:02,040
is that they are just
mindless, aggressive hunters.
359
00:26:02,040 --> 00:26:04,120
And that is not what we're seeing here.
360
00:26:04,320 --> 00:26:09,120
What we are seeing is a calm,
more intelligent approach.
361
00:26:10,440 --> 00:26:15,120
It's strikingly similar to a
tactic used by a legendarily smart hunter.
362
00:26:19,080 --> 00:26:21,880
Killer whales also patiently
stalk fishing boats
363
00:26:22,520 --> 00:26:25,120
striking with intelligent,
surgical precision
364
00:26:25,120 --> 00:26:28,120
once trawlers start
to bring in their catch.
365
00:26:29,160 --> 00:26:33,000
Scientists believe Orcas do this
to deliberately save energy.
366
00:26:34,640 --> 00:26:37,240
Are sharks now rivaling
this clever thinking?
367
00:26:38,720 --> 00:26:40,320
Think of it
from a shark's perspective.
368
00:26:41,520 --> 00:26:43,960
When they hunt,
they expend a lot of energy.
369
00:26:44,560 --> 00:26:46,600
So, a hooked fish presents an opportunity
370
00:26:46,600 --> 00:26:48,960
for a more efficient way
of getting a feed.
371
00:26:52,480 --> 00:26:53,640
Back beneath the boat,
372
00:26:54,400 --> 00:26:59,200
underwater cinematographer Colin
catches a glimpse of something unusual.
373
00:27:00,280 --> 00:27:02,520
COLIN
I think I can see a smaller bull shark.
374
00:27:06,720 --> 00:27:11,240
Yeah, definitely a young
bull shark. That's really weird.
375
00:27:12,760 --> 00:27:15,680
Col reckons that
he saw a juvenile bull shark.
376
00:27:16,360 --> 00:27:18,120
To me, that's unusual.
377
00:27:18,120 --> 00:27:20,640
Why would there be
a small juvenile bull shark
378
00:27:20,640 --> 00:27:23,080
out in the open ocean in adult territory?
379
00:27:25,080 --> 00:27:27,320
Bull sharks have a really
interesting reproductive cycle.
380
00:27:28,040 --> 00:27:31,040
The females come from the ocean up rivers
381
00:27:31,040 --> 00:27:33,640
to lay their pups
in freshwater environments.
382
00:27:35,120 --> 00:27:38,800
Rivers offer protection
and security for bull shark pups.
383
00:27:39,560 --> 00:27:43,560
Only once they reach six to seven feet
or around eight years old,
384
00:27:43,560 --> 00:27:44,960
will they head to the ocean.
385
00:27:45,360 --> 00:27:50,200
If Colin did actually see a juvenile
bull shark this far out offshore,
386
00:27:50,400 --> 00:27:51,720
that's quite a significant find.
387
00:27:52,840 --> 00:27:57,360
It means there could be a bull
shark nursery somewhere nearby.
388
00:27:58,400 --> 00:28:02,760
If that's true, that means juvenile
bull sharks are leaving their nursery
389
00:28:02,960 --> 00:28:06,000
and they're mingling in with these
adults on these fishing grounds.
390
00:28:06,000 --> 00:28:08,600
I think that's something that
needs further investigation.
391
00:28:16,240 --> 00:28:17,920
To prove that there is a nursery,
392
00:28:18,360 --> 00:28:20,320
we need to go and catch
juvenile bull sharks.
393
00:28:20,320 --> 00:28:23,200
And in order for us to do that,
we need to go upriver.
394
00:28:24,480 --> 00:28:28,040
{\an8}Located just 30 miles
from the offshore fishing site,
395
00:28:28,040 --> 00:28:30,120
the Mission River runs through Weipa
396
00:28:30,120 --> 00:28:33,520
and is one of the largest
nearby sources of freshwater.
397
00:28:37,120 --> 00:28:41,160
Searching for baby sharks in an
open river is notoriously difficult.
398
00:28:42,480 --> 00:28:44,920
The trick is to follow the food.
399
00:28:47,280 --> 00:28:49,960
We've got a bunch of birds
just hanging off under the bridge.
400
00:28:52,160 --> 00:28:53,520
It's good. A lot of birds are a good sign.
401
00:28:55,400 --> 00:28:58,520
The birds are taking
advantage of a crowded ball of fish
402
00:28:58,520 --> 00:29:00,080
near the surface of the water.
403
00:29:00,840 --> 00:29:04,880
It's a sign that normally means
there are predators lurking below.
404
00:29:07,560 --> 00:29:10,480
Where we get little fish
big fish follow, right?
405
00:29:10,640 --> 00:29:11,520
That's right.
406
00:29:13,760 --> 00:29:15,760
Maybe we should start
to get our gear together.
407
00:29:16,440 --> 00:29:18,520
What do you think
we should put down first?
408
00:29:19,200 --> 00:29:21,920
- Let's go drum lines first.
- Good idea.
409
00:29:23,080 --> 00:29:27,800
In these silty, low-visibility
waters diving is not an option.
410
00:29:29,200 --> 00:29:33,080
The team needs to bring
whatever's hunting the fish up to them.
411
00:29:34,240 --> 00:29:35,720
This is really actually quite exciting
412
00:29:35,720 --> 00:29:39,720
because we think that we found a location
where there are juvenile bull sharks.
413
00:29:41,200 --> 00:29:42,920
We're going to set up some drum lines.
414
00:29:42,920 --> 00:29:45,280
Just think about
a really long fishing line.
415
00:29:46,680 --> 00:29:47,600
Okay?
416
00:29:47,600 --> 00:29:48,560
Got it?
Line.
417
00:29:50,120 --> 00:29:51,440
- Perfect.
- Here's your way.
418
00:29:51,960 --> 00:29:54,560
Bring us a little bull shark, please.
419
00:29:56,480 --> 00:29:58,960
Once those yellow floats
are no longer visible,
420
00:29:58,960 --> 00:30:01,280
or if the entire
big float bobs underwater,
421
00:30:02,000 --> 00:30:02,920
we're "shark on."
422
00:30:04,440 --> 00:30:05,480
They back off the boat,
423
00:30:06,600 --> 00:30:08,520
and wait for something to bite.
424
00:30:14,720 --> 00:30:16,440
Guys. I think the floats are down.
425
00:30:16,440 --> 00:30:17,960
All right, cool. Yep, the floats are down,
426
00:30:17,960 --> 00:30:20,040
we can't see the yellows. That's great.
427
00:30:28,360 --> 00:30:31,200
He's definitely on.
He's still on. He's still on.
428
00:30:31,960 --> 00:30:32,960
There he is. Here he is.
Here he is. Alright.
429
00:30:32,960 --> 00:30:34,640
Oh, yes. That's a nice little belly.
430
00:30:36,560 --> 00:30:40,120
It looks like-- oh, that could be a bull.
That looks like-- that looks like a bull.
431
00:30:40,120 --> 00:30:42,160
Bull shark!
This is great. I think we're on.
432
00:30:42,480 --> 00:30:45,920
This is exactly what we came here for.
433
00:30:47,400 --> 00:30:49,360
Genetic analyses of this juvenile
434
00:30:49,360 --> 00:30:54,240
could provide vital details
about Weipa's bull shark population,
435
00:30:54,240 --> 00:30:56,840
but only after it's brought
alongside the boat.
436
00:30:57,360 --> 00:30:58,960
Guys, get that tail rope on.
437
00:30:58,960 --> 00:31:00,280
- Thank you.
She's strong.
438
00:31:01,200 --> 00:31:03,480
Hang on, hang on she's come
back around. Swing back round.
439
00:31:05,000 --> 00:31:08,760
Baby bulls are born
with a mouth full of razor-sharp teeth.
440
00:31:11,360 --> 00:31:13,960
And they're even more agile than adults.
441
00:31:16,360 --> 00:31:17,720
He's going--
he's going too far forward.
442
00:31:18,840 --> 00:31:21,680
- Just keep this in gear, in back here.
You got it.
443
00:31:22,440 --> 00:31:24,160
They might be small,
but they still can bite.
444
00:31:25,360 --> 00:31:27,080
Fighter, yeah. I lost it.
445
00:31:30,680 --> 00:31:32,320
Whoa!
He's a fighter.
446
00:31:32,320 --> 00:31:33,400
That's great.
447
00:31:35,680 --> 00:31:37,080
Towing, off. Ready?
Yes!
448
00:31:37,080 --> 00:31:37,960
Grab that rope.
449
00:31:39,920 --> 00:31:41,680
Oh, it's a female.
450
00:31:42,480 --> 00:31:44,240
Hello, cutey.
451
00:31:45,120 --> 00:31:48,880
The shark is under control.
It's one meter 40.
452
00:31:49,640 --> 00:31:52,880
I would say she's been here,
for about five years.
453
00:31:53,800 --> 00:31:55,560
Measuring under five feet,
454
00:31:55,760 --> 00:31:59,160
it's highly unlikely this shark
traveled here by sea.
455
00:32:00,040 --> 00:32:01,800
She's definitely from this river system.
456
00:32:02,880 --> 00:32:04,840
So, I'm pretty confident there's
even smaller ones around.
457
00:32:06,640 --> 00:32:07,920
Capturing this juvenile bull shark
458
00:32:08,560 --> 00:32:11,160
indicates that there is
a nursery in this river.
459
00:32:12,400 --> 00:32:14,520
This means that there is
an easy connection
460
00:32:14,520 --> 00:32:18,640
between this nursery
and the offshore population.
461
00:32:20,040 --> 00:32:22,840
An easy connection
means more opportunities
462
00:32:22,840 --> 00:32:26,600
{\an8}for juveniles to mingle
with adult sharks out at sea.
463
00:32:28,600 --> 00:32:33,440
Bull sharks don't have parental care,
and they're usually solitary animals.
464
00:32:34,080 --> 00:32:37,880
So, seeing them interact together,
we get a lot of questions.
465
00:32:39,480 --> 00:32:43,160
Previous research has shown
that a lot of species, including sharks,
466
00:32:43,160 --> 00:32:47,280
have the ability to learn new
behaviors in a social setting.
467
00:32:47,840 --> 00:32:49,480
Is that how bull sharks in Weipa
468
00:32:49,480 --> 00:32:52,400
are actually picking up
this depredation behavior?
469
00:32:55,440 --> 00:32:57,600
Catching a juvenile bull shark
470
00:32:57,600 --> 00:33:01,520
also allows Johan and Mariel
to test another theory.
471
00:33:02,120 --> 00:33:04,040
Alright, were going to
need a biopsy sample.
472
00:33:05,720 --> 00:33:08,440
Bull sharks tend to migrate
with the seasons
473
00:33:08,440 --> 00:33:10,360
because the water temperature changes.
474
00:33:10,920 --> 00:33:15,280
So as it cools, bull sharks will move
into the more constant warmer waters.
475
00:33:16,120 --> 00:33:20,440
But that rule might not apply in
this tropical part of northern Australia.
476
00:33:21,600 --> 00:33:22,440
Up here in The Top End,
477
00:33:22,440 --> 00:33:24,560
the water temperature doesn't
really fluctuate as much.
478
00:33:26,400 --> 00:33:27,680
The sharks around Weipa
479
00:33:27,680 --> 00:33:32,360
could be resisting their migratory
instincts and putting down roots.
480
00:33:33,200 --> 00:33:35,600
If that's true and they
are staying in the one area,
481
00:33:36,480 --> 00:33:38,640
that means social learning behaviors
482
00:33:38,640 --> 00:33:42,600
could be offloaded
to younger sharks more often.
483
00:33:44,240 --> 00:33:47,680
Proving this theory
will take years of field work and tagging.
484
00:33:48,360 --> 00:33:53,120
But cutting-edge genetic analysis
could offer a sneak-peek at the results.
485
00:33:54,960 --> 00:33:57,480
DNA can tell us
a lot of interesting stuff.
486
00:33:58,080 --> 00:34:01,760
We can test it against other
populations around Australia.
487
00:34:01,760 --> 00:34:05,560
It can tell us if there's
any genetic differences.
488
00:34:05,560 --> 00:34:09,240
It can also tell us how related
sharks are to each other.
489
00:34:10,480 --> 00:34:11,320
I think we're good here.
490
00:34:11,320 --> 00:34:13,400
I think we can get ready to release,
so we're going to take off the tail rope.
491
00:34:14,120 --> 00:34:15,120
Okay, tail's out.
492
00:34:17,880 --> 00:34:18,680
Off she goes.
493
00:34:21,560 --> 00:34:23,160
Whew! How good?!
494
00:34:23,160 --> 00:34:26,160
- Oh, nice. That was great.
- Yes! What fun!
495
00:34:27,840 --> 00:34:29,880
To complete their investigation
496
00:34:29,880 --> 00:34:34,440
and find out if the bull sharks around
Weipa are putting down roots,
497
00:34:34,840 --> 00:34:40,600
Johan and Mariel need to get DNA samples
from adult sharks back out at sea.
498
00:34:43,280 --> 00:34:45,960
On the way, there's a temporary diversion.
499
00:34:48,040 --> 00:34:49,480
A ping from the fin cam
500
00:34:49,720 --> 00:34:53,000
they attached to a big bull shark
several days ago.
501
00:34:55,560 --> 00:34:58,120
We're trying to find it
by tracking its signal
502
00:34:58,120 --> 00:35:00,160
so we can download and get the data.
503
00:35:02,800 --> 00:35:05,080
I think it's coming near the shore.
504
00:35:09,160 --> 00:35:10,000
There it is.
505
00:35:11,880 --> 00:35:13,240
Oh yeah, I can see it.
506
00:35:18,360 --> 00:35:22,640
The data from the fin cam
showed us some amazing information.
507
00:35:23,440 --> 00:35:25,320
Generally, bull sharks that I've tagged
508
00:35:26,480 --> 00:35:29,680
spend more of their time
at the ocean floor during the day.
509
00:35:30,640 --> 00:35:34,520
Normally they use the
cover of night to patrol at the surface.
510
00:35:35,400 --> 00:35:37,000
That's not what we're
seeing here in Weipa.
511
00:35:37,880 --> 00:35:41,480
We're seeing the bull shark
spending time at the water's surface
512
00:35:41,920 --> 00:35:45,120
and then going all the way back down
to the sea floor during the day.
513
00:35:45,800 --> 00:35:49,360
The fin cam
captures the shark repeatedly diving
514
00:35:49,360 --> 00:35:51,240
and then returning to the surface.
515
00:35:52,800 --> 00:35:54,840
This is what we call "yo-yo diving."
516
00:35:54,840 --> 00:35:59,480
The yo-yo behavior is generally associated
with a type of patrolling behavior.
517
00:35:59,480 --> 00:36:01,160
Basically, the shark's looking for food.
518
00:36:02,400 --> 00:36:07,320
But why is this bull shark doing it during
the day when they're generally nocturnal?
519
00:36:08,160 --> 00:36:09,320
That is a significant question.
520
00:36:10,200 --> 00:36:13,320
It's yet another anomaly
amongst the local bull sharks.
521
00:36:15,040 --> 00:36:17,840
Is it somehow related
to the recreational fishing?
522
00:36:18,920 --> 00:36:21,400
Are they looking for
recreational fishing catches?
523
00:36:25,000 --> 00:36:26,320
This is a good piece of the puzzle,
524
00:36:27,400 --> 00:36:30,800
but we have to remember
that it is only one animal,
525
00:36:30,800 --> 00:36:36,880
one incident in one video shot so far,
but it does start to raise questions.
526
00:36:37,480 --> 00:36:40,280
To conclude something,
we really need to get more data first.
527
00:36:44,800 --> 00:36:47,040
It's the team's final day in Weipa.
528
00:36:48,400 --> 00:36:51,560
Strong winds will soon force
the mothership back to port.
529
00:36:53,640 --> 00:36:57,680
This is our last dive here.
And we need to get more DNA samples.
530
00:36:58,320 --> 00:37:01,680
Basically, the higher the number
of biopsy samples we have
531
00:37:01,840 --> 00:37:05,160
is the greater our strength in our
conclusions that we can come up with.
532
00:37:08,600 --> 00:37:13,000
To collect the DNA,
Johan is armed with a modified spear gun.
533
00:37:13,560 --> 00:37:18,720
This will maximize his chances of getting
multiple samples from one dive.
534
00:37:21,640 --> 00:37:25,440
Wade fishes topside once again
to draw the sharks in.
535
00:37:30,400 --> 00:37:34,600
Yes, we've got two
sharks below us. Two sharks. Over.
536
00:37:37,160 --> 00:37:39,160
Although we're seeing the bull sharks,
537
00:37:39,800 --> 00:37:41,400
we still need to get them
a little bit closer
538
00:37:41,400 --> 00:37:43,640
so that we can get
a biopsy sample from them.
539
00:37:44,880 --> 00:37:47,280
The cage is positioned closer to Wade
540
00:37:47,800 --> 00:37:50,800
to increase Johan's
chances of a clean shot.
541
00:37:53,400 --> 00:37:55,200
COLIN
Bull shark at 12 o'clock.
542
00:37:56,320 --> 00:37:57,520
six or seven meters out.
543
00:37:59,520 --> 00:38:01,080
It's high-noon for Johan,
544
00:38:01,280 --> 00:38:05,320
but before he's had a chance
to pull the trigger, disaster.
545
00:38:06,600 --> 00:38:08,280
COLIN
There's this murk coming through.
546
00:38:09,320 --> 00:38:11,600
A cloud of silt envelopes the cage.
547
00:38:12,760 --> 00:38:14,560
JOHAN
We're right on the edge of visibility.
548
00:38:16,520 --> 00:38:19,760
Giant bull sharks
just meters away from the divers
549
00:38:19,760 --> 00:38:21,120
have become invisible.
550
00:38:22,480 --> 00:38:25,800
The visibility
is getting worse and worse.
551
00:38:26,760 --> 00:38:27,920
With fish in the water,
552
00:38:28,080 --> 00:38:32,360
an unseen shark could easily
collide with the cage.
553
00:38:40,920 --> 00:38:44,520
Surface to divers,
we have a 20-minute bottom time
554
00:38:44,520 --> 00:38:48,600
due to conditions have just started
to creep up, up here.
555
00:38:48,600 --> 00:38:51,480
Okay divers, you've got 20 minutes,
20 minutes, 20 minutes.
556
00:38:53,720 --> 00:38:56,480
Time is running out
to get the DNA samples.
557
00:39:01,760 --> 00:39:04,120
COLIN
Johan. Bull shark to your left.
558
00:39:09,520 --> 00:39:13,440
Coming in closer.
Take the shot! Take the shot!
559
00:39:17,280 --> 00:39:18,960
Got him! Yes!
560
00:39:21,400 --> 00:39:22,840
It's the perfect shot.
561
00:39:24,320 --> 00:39:28,040
The shark is none-the-wiser
and disappears as if nothing's happened.
562
00:39:29,920 --> 00:39:33,760
Divers. Divers. Five
more minutes. Five more minutes. Over.
563
00:39:34,760 --> 00:39:37,400
There's still
a few more minutes on the clock.
564
00:39:47,480 --> 00:39:48,920
COLIN
We've got another one coming in.
565
00:39:53,640 --> 00:39:57,840
Yes! A second biopsy
in the bag. Nice shot.
566
00:39:58,720 --> 00:40:01,200
It's another crucial sample.
567
00:40:02,040 --> 00:40:05,640
Divers to surface.
You can start bringing us up.
568
00:40:06,560 --> 00:40:07,680
Mission success.
569
00:40:10,000 --> 00:40:12,760
Copy, copy.
We'll bring you close to the surface.
570
00:40:18,040 --> 00:40:19,640
COLIN
That was a better dive, wasn't it?
571
00:40:19,640 --> 00:40:22,720
That was awesome. That
was great. It actually worked really well.
572
00:40:23,160 --> 00:40:24,760
I don't know about you,
but I count that as a win.
573
00:40:25,040 --> 00:40:25,960
I think we've done well.
574
00:40:26,760 --> 00:40:30,720
Despite the unpredictable
weather, the team have what they need.
575
00:40:31,800 --> 00:40:36,200
We got several biopsy samples from
a range of different sizes of bull sharks
576
00:40:36,200 --> 00:40:38,760
that we've sent
to the laboratory to analyze.
577
00:40:44,360 --> 00:40:46,440
The DNA results are in.
578
00:40:47,400 --> 00:40:52,720
It's a small sample size, but they've
delivered truly intriguing data.
579
00:40:54,120 --> 00:40:58,440
What the DNA has shown us,
is that the shark we sampled upriver
580
00:40:59,480 --> 00:41:01,480
is half related to the large female
581
00:41:01,480 --> 00:41:03,880
that we sampled offshore
in that last cage dive.
582
00:41:06,040 --> 00:41:08,840
Further analysis
indicates that the third sample
583
00:41:09,440 --> 00:41:12,760
is also related to both these sharks.
584
00:41:14,840 --> 00:41:19,440
Due to the small sample size
that we have, I'm completely surprised,
585
00:41:19,440 --> 00:41:24,480
and I did not expect any of these sharks
to be in any way related to each other.
586
00:41:26,240 --> 00:41:28,080
We don't know
if it's a mother or a father
587
00:41:28,360 --> 00:41:32,960
but we do know that they're sharing
an ancestor in-between them.
588
00:41:35,200 --> 00:41:38,680
It's a strong family link
connecting the bull sharks in the nursery
589
00:41:39,640 --> 00:41:41,960
to the adults raiding
the fishermen at sea.
590
00:41:45,040 --> 00:41:48,680
It may also implicate
that compared to other areas
591
00:41:48,680 --> 00:41:51,400
these sharks may not
be moving in large numbers.
592
00:41:52,520 --> 00:41:56,080
The closer related the
sharks, the smaller the gene pool,
593
00:41:56,320 --> 00:41:58,440
and the less they could be moving away.
594
00:41:58,920 --> 00:42:01,400
If they're not
migrating the large distances
595
00:42:01,400 --> 00:42:04,240
and they're spending
more time in this one area,
596
00:42:05,040 --> 00:42:07,920
that could explain why
the depredation events
597
00:42:07,920 --> 00:42:11,080
are so much higher
and concentrate here in Weipa.
598
00:42:14,040 --> 00:42:17,680
If the populations of bull sharks
up here at Weipa are localized,
599
00:42:17,680 --> 00:42:22,200
they would be exposed
constantly to fishing activities,
600
00:42:22,800 --> 00:42:26,600
increasing their likelihood
of depredation behaviors.
601
00:42:30,640 --> 00:42:34,000
Together with the presence
of the nearby bull shark nursery,
602
00:42:34,840 --> 00:42:39,080
it could put Weipa at the
epicenter of a perfect storm.
603
00:42:40,640 --> 00:42:43,400
It's definitely possible
that juvenile bull sharks
604
00:42:43,600 --> 00:42:45,960
could be learning
the behaviors from adults.
605
00:42:46,520 --> 00:42:50,920
We've seen smaller
sharks leaving the river earlier...
606
00:42:50,920 --> 00:42:52,560
JOHAN
Definitely a young bull shark.
607
00:42:52,560 --> 00:42:56,240
...and potentially
starting the social interactions
608
00:42:56,240 --> 00:42:58,560
and learning procedures at a younger age.
609
00:42:59,720 --> 00:43:02,520
Seeing this bull shark
behavior has been amazing.
610
00:43:02,520 --> 00:43:04,200
However, it's also been surprising.
611
00:43:06,120 --> 00:43:08,320
The raids on
fishermen have been exposed
612
00:43:08,320 --> 00:43:11,520
as the work of a methodical,
calculated hunter.
613
00:43:13,680 --> 00:43:15,240
They're highly intelligent.
614
00:43:15,680 --> 00:43:20,000
They're analyzing their environment
before they do anything.
615
00:43:21,600 --> 00:43:24,360
These smart bull sharks
might be at the vanguard
616
00:43:24,360 --> 00:43:28,840
of an adapting shark behavior
that could soon spread elsewhere.
617
00:43:31,960 --> 00:43:35,120
{\an8}Recreational fishing
is increasing worldwide.
618
00:43:36,080 --> 00:43:38,920
{\an8}We're starting to see a lot
more anger towards sharks,
619
00:43:39,480 --> 00:43:43,520
{\an8}and that could lead to a downward
spiral towards shark conservation.
620
00:43:44,880 --> 00:43:48,320
{\an8}That's why it's important when we get
opportunities like up here in Weipa
621
00:43:49,280 --> 00:43:51,200
{\an8}that we grab them with both hands.
622
00:43:52,520 --> 00:43:53,960
{\an8}There's a lot more to uncover.
623
00:43:53,960 --> 00:43:57,560
{\an8}And I am looking forward to coming back
and spending a lot more time here.