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.