1 00:00:34,200 --> 00:00:40,200 Here in Britain and Ireland, we have some of the richest seas in Europe. 2 00:00:41,360 --> 00:00:45,840 Our varied coastline, if you include all the many offshore islands, 3 00:00:45,840 --> 00:00:48,560 is over 22,000 miles long, 4 00:00:48,560 --> 00:00:52,520 and none of us live more than 70 miles away from the sea. 5 00:00:53,520 --> 00:00:57,040 Yet few of us have seen the wonders beyond the beach 6 00:00:57,040 --> 00:00:59,000 and beneath the waves. 7 00:00:59,000 --> 00:01:01,440 In this episode, we will take you 8 00:01:01,440 --> 00:01:03,920 from the most southerly point of the 9 00:01:03,920 --> 00:01:06,600 United Kingdom to the furthest north, 10 00:01:06,600 --> 00:01:10,120 to explain why our seas can be so productive 11 00:01:10,120 --> 00:01:13,400 and reveal the threats that they face today. 12 00:01:28,880 --> 00:01:33,720 Every winter, a warm ocean current, the gulf stream, 13 00:01:33,720 --> 00:01:37,280 drives huge storms across the Atlantic... 14 00:01:39,520 --> 00:01:44,680 ..away from the Caribbean and straight towards our shores. 15 00:01:49,320 --> 00:01:54,400 There, every winter, they batter the west coasts of our islands. 16 00:02:03,720 --> 00:02:07,200 Waves with energy built up across an entire ocean 17 00:02:07,200 --> 00:02:09,640 are hurled at our coasts. 18 00:02:14,040 --> 00:02:16,920 Walls of water more than ten metres tall 19 00:02:16,920 --> 00:02:19,520 crash repeatedly onto the rocks. 20 00:02:32,680 --> 00:02:35,440 And as the water at depth is churned, 21 00:02:35,440 --> 00:02:38,840 it brings nutrients up towards the surface. 22 00:02:44,640 --> 00:02:49,000 These nutrients, combined with the warmth of the gulf stream, 23 00:02:49,000 --> 00:02:53,160 are the reason why marine life here proliferates 24 00:02:53,160 --> 00:02:56,400 with such extraordinary richness and variety. 25 00:03:23,520 --> 00:03:25,640 Each year, in autumn, 26 00:03:25,640 --> 00:03:29,800 evidence of this marine abundance appears on land. 27 00:03:34,880 --> 00:03:40,080 13,000 grey seals haul out on Blakeney Point in Norfolk. 28 00:03:41,600 --> 00:03:44,720 It's the largest seal colony in England. 29 00:03:47,280 --> 00:03:51,080 Females, having spent most of the year feeding in our rich waters, 30 00:03:51,080 --> 00:03:53,560 are preparing to produce their young. 31 00:03:55,200 --> 00:03:57,960 Newly born, the pups are helpless... 32 00:04:00,640 --> 00:04:04,640 ..and for their first few weeks, entirely dependent on their mothers. 33 00:04:06,360 --> 00:04:09,400 Seal milk is more than 50% fat... 34 00:04:10,360 --> 00:04:13,320 ..and the pups put on two kilos a day. 35 00:04:17,080 --> 00:04:20,800 At first, parent and pup are inseparable. 36 00:04:24,960 --> 00:04:29,800 But then, after a few days, the youngsters start to explore. 37 00:04:32,200 --> 00:04:35,080 Other females don't tolerate the appearance 38 00:04:35,080 --> 00:04:37,800 of unrelated pups on their patch. 39 00:04:57,360 --> 00:05:00,360 Posing an even greater threat than the females... 40 00:05:01,360 --> 00:05:03,200 ..are the males. 41 00:05:10,720 --> 00:05:14,080 Three metres long and weighing 350 kilos... 42 00:05:15,880 --> 00:05:18,400 ..they have come here to mate. 43 00:05:22,320 --> 00:05:25,640 They know that soon after the pups are born, 44 00:05:25,640 --> 00:05:29,760 the females will become sexually receptive once again. 45 00:05:33,760 --> 00:05:36,960 This big male tries to control all the females 46 00:05:36,960 --> 00:05:39,160 on this stretch of the beach. 47 00:05:42,760 --> 00:05:45,280 But he has a rival. 48 00:05:53,000 --> 00:05:54,720 ROARS 49 00:05:54,720 --> 00:05:58,040 The big male warns off the challenger, 50 00:05:58,040 --> 00:06:00,560 but the intruder takes no notice. 51 00:06:00,560 --> 00:06:02,400 ROARS 52 00:06:07,240 --> 00:06:09,480 There's only one way to settle this. 53 00:06:11,480 --> 00:06:13,160 Violence. 54 00:06:24,640 --> 00:06:26,600 When the males fight, 55 00:06:26,600 --> 00:06:29,440 they take no notice of any pup that gets in their way. 56 00:06:32,240 --> 00:06:34,120 GRUNTS 57 00:06:34,120 --> 00:06:36,120 The pup's mother intervenes... 58 00:06:40,600 --> 00:06:43,320 ..allowing her pup to wriggle away. 59 00:06:50,000 --> 00:06:53,280 Finally, the battle turns. 60 00:06:57,520 --> 00:07:01,040 The intruder starts to retreat towards the sea. 61 00:07:04,640 --> 00:07:07,600 Now, the smaller males join the chase. 62 00:07:20,760 --> 00:07:24,680 The big male has retained his right to mate. 63 00:07:29,760 --> 00:07:33,760 Despite these battles, Blakeney Point still provides the pups 64 00:07:33,760 --> 00:07:35,920 with an excellent start in life. 65 00:07:37,560 --> 00:07:40,200 5,000 are born here each year. 66 00:07:44,240 --> 00:07:48,240 A remarkable 40% of the world population of grey seals 67 00:07:48,240 --> 00:07:50,680 lives around the British Isles. 68 00:07:52,440 --> 00:07:55,800 Impressive evidence of the richness of our seas. 69 00:08:01,160 --> 00:08:04,960 Beneath the surface, that wealth is very evident. 70 00:08:15,800 --> 00:08:19,200 Cold, nutrient-rich currents from the north 71 00:08:19,200 --> 00:08:22,680 mingle with the warm waters of the gulf stream, 72 00:08:22,680 --> 00:08:26,920 and support an astonishing variety of plants and animals. 73 00:08:31,720 --> 00:08:35,080 There are more than 10,000 different species here. 74 00:09:09,920 --> 00:09:14,120 The effect of the gulf stream is felt most keenly 75 00:09:14,120 --> 00:09:18,280 at our southernmost point, around the Isles of Scilly. 76 00:09:21,680 --> 00:09:25,000 Here grows one of the biggest stretches of seagrass 77 00:09:25,000 --> 00:09:28,600 to be found anywhere in British and Irish waters. 78 00:09:31,360 --> 00:09:35,840 Seagrass is important globally because it collects carbon 79 00:09:35,840 --> 00:09:39,920 up to 35 times faster than a tropical rainforest. 80 00:09:42,960 --> 00:09:46,680 But we have lost nearly 90% of our seagrass, 81 00:09:46,680 --> 00:09:50,760 mainly because of pollution and disturbance of the seabed. 82 00:09:54,160 --> 00:09:57,120 Nonetheless, these marine meadows 83 00:09:57,120 --> 00:10:00,600 are home to a wide variety of small animals. 84 00:10:02,160 --> 00:10:06,600 Including this perhaps somewhat surprising one. 85 00:10:11,440 --> 00:10:14,120 A spiny seahorse. 86 00:10:15,200 --> 00:10:18,680 One of just two species of seahorse that live in our waters. 87 00:10:24,520 --> 00:10:28,120 They thrive in the warmth brought by the gulf stream. 88 00:10:35,800 --> 00:10:37,920 The seagrass provides them 89 00:10:37,920 --> 00:10:41,040 with the seclusion they prefer for their courtship. 90 00:10:54,320 --> 00:10:57,880 A crucial part of their underwater dance 91 00:10:57,880 --> 00:11:01,960 involves a gentle entwining of their tails. 92 00:11:05,720 --> 00:11:09,400 It's behaviour you might think to be more typical 93 00:11:09,400 --> 00:11:12,800 of the warm, balmy waters of the Mediterranean. 94 00:11:22,320 --> 00:11:24,600 And there is another creature 95 00:11:24,600 --> 00:11:27,840 that is also more usually found in warmer waters. 96 00:11:32,560 --> 00:11:34,600 The common cuttlefish. 97 00:11:38,040 --> 00:11:42,160 It's the most northerly of all cuttlefish species. 98 00:11:44,560 --> 00:11:48,480 This pregnant female, about the size of a rugby football, 99 00:11:48,480 --> 00:11:53,120 is being guarded by a male as she prepares to lay her eggs. 100 00:11:55,640 --> 00:11:58,680 First, she cleans her chosen site 101 00:11:58,680 --> 00:12:02,200 by squirting jets of water over the seaweed. 102 00:12:05,600 --> 00:12:08,440 Several dozen black eggs are already here, 103 00:12:08,440 --> 00:12:10,880 having been laid the previous day. 104 00:12:21,920 --> 00:12:24,040 And now she adds more... 105 00:12:25,040 --> 00:12:29,760 ..one by one, until there are up to 3,000 or so. 106 00:12:39,240 --> 00:12:41,200 A month later... 107 00:12:44,080 --> 00:12:48,480 ..during the night, the eggs start to hatch. 108 00:12:54,840 --> 00:13:00,200 A perfectly formed baby cuttlefish, no larger than a pea. 109 00:13:07,040 --> 00:13:09,280 Within a few weeks, 110 00:13:09,280 --> 00:13:12,720 a male has grown to a length of around six centimetres 111 00:13:12,720 --> 00:13:15,760 and is already a stealthy hunter. 112 00:13:26,560 --> 00:13:31,360 His eyesight is so sensitive that he's able to hunt by moonlight. 113 00:13:54,080 --> 00:13:56,360 But when the moon disappears... 114 00:13:58,480 --> 00:14:01,040 ..even he cannot see 115 00:14:01,040 --> 00:14:05,400 and the darkness usually brings hunting to an end. 116 00:14:10,240 --> 00:14:12,640 But on just a few nights each year... 117 00:14:13,560 --> 00:14:16,120 ..something extraordinary happens. 118 00:14:20,160 --> 00:14:26,520 Tiny light-producing algae create vast clouds of bioluminescence. 119 00:14:31,200 --> 00:14:36,240 They're stimulated to switch on by any sudden movement in the water. 120 00:14:42,800 --> 00:14:46,560 Even the slight swirl produced by a tiny crab as it breathes 121 00:14:46,560 --> 00:14:48,480 has an effect. 122 00:14:52,480 --> 00:14:55,240 The hunter must move very smoothly, 123 00:14:55,240 --> 00:14:58,320 to avoid creating a light show of his own. 124 00:15:26,600 --> 00:15:30,560 The light of the algae has enabled it to see its prey 125 00:15:30,560 --> 00:15:33,080 and so hunt throughout the night. 126 00:15:40,840 --> 00:15:44,760 A year later, the cuttlefish are fully grown 127 00:15:44,760 --> 00:15:48,240 and this male is now looking for a female. 128 00:15:51,640 --> 00:15:55,600 But the traditional breeding site is empty. 129 00:16:03,640 --> 00:16:06,160 The cuttlefish that gathered here to mate... 130 00:16:07,560 --> 00:16:10,240 ..have been caught in a fishing pot. 131 00:16:14,840 --> 00:16:18,360 They may be among the most intelligent animals in the sea... 132 00:16:20,160 --> 00:16:23,520 ..but they've been fooled by a simple trap. 133 00:16:26,880 --> 00:16:29,920 And once in it, there is no escape. 134 00:16:47,200 --> 00:16:51,680 The male outside spots a possible mate. 135 00:17:00,120 --> 00:17:02,240 But he can't reach her. 136 00:17:15,680 --> 00:17:20,520 Our cuttlefish population can tolerate some loss to fishing, 137 00:17:20,520 --> 00:17:25,680 but surely we shouldn't put pots where they habitually breed, 138 00:17:25,680 --> 00:17:29,320 and prevent them from producing their next generation 139 00:17:46,040 --> 00:17:52,120 Away from the coast, the seabed may seem barren and lifeless. 140 00:17:54,000 --> 00:17:56,760 But looks can be deceptive. 141 00:17:59,400 --> 00:18:04,280 This muddy seafloor is rich in bacteria and algae 142 00:18:04,280 --> 00:18:08,800 and provides food for one animal in particular. 143 00:18:10,560 --> 00:18:15,200 A slow-moving creature that can grow up to a length of six centimetres. 144 00:18:18,080 --> 00:18:21,360 The royal flush sea slug. 145 00:18:25,680 --> 00:18:28,840 Thousands graze the seafloor here. 146 00:18:33,520 --> 00:18:36,600 But with so much competition for the same food, 147 00:18:36,600 --> 00:18:38,840 supplies eventually run out. 148 00:18:40,600 --> 00:18:43,240 And the sea slugs have to move on... 149 00:18:44,200 --> 00:18:46,560 ..in their own strange way. 150 00:18:50,480 --> 00:18:55,640 They flap their wing-like mantles and rise up from the seabed. 151 00:19:02,040 --> 00:19:06,840 Drifting on the slow current, they can travel for miles. 152 00:19:26,800 --> 00:19:32,040 This extraordinary mass migration has never been filmed before. 153 00:19:47,560 --> 00:19:51,680 Eventually, they reach new feeding grounds. 154 00:20:04,880 --> 00:20:09,640 And now they can start hoovering the seabed once more. 155 00:20:19,440 --> 00:20:22,360 As spring turns to summer, 156 00:20:22,360 --> 00:20:27,680 another very different migration begins all along the south coast, 157 00:20:27,680 --> 00:20:30,160 and for a very different reason. 158 00:20:34,120 --> 00:20:36,800 A young female spider crab. 159 00:20:39,880 --> 00:20:44,960 She is searching these sandy plains for others of her own kind. 160 00:20:55,040 --> 00:20:57,840 Spider crabs are normally solitary, 161 00:20:57,840 --> 00:21:02,680 but now, in the summer, they start to assemble into groups. 162 00:21:06,200 --> 00:21:11,040 And then, when there are enough of them, they start to travel. 163 00:21:20,480 --> 00:21:24,080 Together, they journey for miles across the seabed, 164 00:21:24,080 --> 00:21:27,360 all heading in the same direction. 165 00:21:40,400 --> 00:21:42,480 Groups join together 166 00:21:42,480 --> 00:21:47,520 and the travellers become one great horde, several-thousand strong. 167 00:21:52,240 --> 00:21:56,240 They are about to face the most dangerous time of their lives. 168 00:22:01,640 --> 00:22:07,120 They have outgrown their hard shells and must now escape from them. 169 00:22:11,880 --> 00:22:14,280 A new shell is expandable, 170 00:22:14,280 --> 00:22:17,680 but it remains soft for several hours 171 00:22:17,680 --> 00:22:21,520 and until it hardens, its owner has no defence. 172 00:22:27,680 --> 00:22:31,040 That is why they've made this journey together. 173 00:22:35,000 --> 00:22:37,960 There is safety in numbers. 174 00:22:47,000 --> 00:22:51,000 Ocean currents are one reason why our waters are so rich. 175 00:22:51,000 --> 00:22:55,200 Another is the exceptional size of our tides. 176 00:22:56,640 --> 00:22:58,840 Vast amounts of water 177 00:22:58,840 --> 00:23:01,760 are continuously transported around our islands 178 00:23:01,760 --> 00:23:03,920 by these powerful currents. 179 00:23:07,200 --> 00:23:10,720 The third biggest tidal rise and fall on the planet 180 00:23:10,720 --> 00:23:13,960 occurs in the estuary of the River Severn. 181 00:23:18,240 --> 00:23:20,240 From low tide, 182 00:23:20,240 --> 00:23:24,320 the sea level rises by as much as the height of a five-storey building 183 00:23:24,320 --> 00:23:28,040 and then falls again, twice every day. 184 00:23:32,240 --> 00:23:36,320 These huge transformations churn-up the nutrients 185 00:23:36,320 --> 00:23:39,120 and replenish the mudflats. 186 00:23:49,040 --> 00:23:52,240 Further north, on the west coast of Scotland, 187 00:23:52,240 --> 00:23:56,560 the power of our tides creates another great spectacle. 188 00:24:00,920 --> 00:24:03,320 The Corryvreckan whirlpool. 189 00:24:03,320 --> 00:24:05,800 25 metres across. 190 00:24:12,800 --> 00:24:15,800 It's the third largest whirlpool in the world. 191 00:24:22,320 --> 00:24:25,960 These powerful tidal currents mix-up the water, 192 00:24:25,960 --> 00:24:30,680 constantly bringing nutrients from the depths up to the surface layers. 193 00:24:36,240 --> 00:24:41,200 And the influence of the tides can extend right down to the seafloor. 194 00:24:45,640 --> 00:24:49,720 The animals down here thrive in these ever-moving currents. 195 00:24:49,720 --> 00:24:53,400 Every square inch is bursting with life. 196 00:25:00,400 --> 00:25:04,480 The flowing water brings a never-ending supply of food. 197 00:25:05,840 --> 00:25:10,400 Brittle stars and sea cucumbers compete to collect all they can. 198 00:25:20,960 --> 00:25:24,600 So many creatures inevitably attracts predators. 199 00:25:33,840 --> 00:25:37,720 The seven-armed starfish - half a metre across. 200 00:25:40,120 --> 00:25:43,480 The brittle stars do their best to get out of their way. 201 00:25:49,920 --> 00:25:53,280 The huge starfish feel for their prey 202 00:25:53,280 --> 00:25:56,200 using hundreds of sensitive tubed feet 203 00:25:56,200 --> 00:25:59,080 that line the underside of their arms. 204 00:26:01,640 --> 00:26:05,920 Yet, not every animal they encounter tries to escape. 205 00:26:09,080 --> 00:26:11,960 This hermit crab, with its powerful claws, 206 00:26:11,960 --> 00:26:14,520 is well able to defend itself. 207 00:26:24,880 --> 00:26:29,840 Finally, the persistent starfish find what they're looking for. 208 00:26:35,720 --> 00:26:37,840 A queen scallop. 209 00:26:41,640 --> 00:26:46,880 Its lines of simple black eyes are able to detect fast-moving threats. 210 00:26:49,400 --> 00:26:52,440 But the starfish moves quite slowly... 211 00:26:54,920 --> 00:26:57,640 ..and the scallop doesn't notice. 212 00:27:00,400 --> 00:27:03,680 Only when the scallop feels the predator's probing feet, 213 00:27:03,680 --> 00:27:05,600 does it react. 214 00:27:11,560 --> 00:27:15,720 It swims away by clapping together the two parts of its shell. 215 00:27:21,840 --> 00:27:24,880 It's a surprisingly effective technique, 216 00:27:24,880 --> 00:27:28,200 and with luck will carry the scallop to safety. 217 00:27:32,880 --> 00:27:36,520 But scallops don't have a strong sense of direction... 218 00:27:39,720 --> 00:27:43,080 ..and the starfish just keep coming. 219 00:27:46,760 --> 00:27:50,720 The starfish first pulls the scallop shell apart 220 00:27:50,720 --> 00:27:53,920 and then inserts its extendable stomach 221 00:27:53,920 --> 00:27:56,360 to digest the scallop's flesh. 222 00:27:59,120 --> 00:28:02,160 The smell of the feast drifts through the water 223 00:28:02,160 --> 00:28:04,240 and attracts scavengers. 224 00:28:07,440 --> 00:28:09,000 Whelks. 225 00:28:10,920 --> 00:28:13,320 They are the clean-up crew. 226 00:28:18,760 --> 00:28:23,720 Tidal beds like these can easily be destroyed by bottom-trawling. 227 00:28:25,640 --> 00:28:28,400 Protecting those that survive is essential 228 00:28:28,400 --> 00:28:31,400 if we are to preserve the richness of our seas. 229 00:28:38,320 --> 00:28:42,440 100 miles from mainland Scotland lies Shetland, 230 00:28:42,440 --> 00:28:45,240 the most northerly part of the British Isles. 231 00:28:47,680 --> 00:28:50,440 Because this archipelago is in the open ocean, 232 00:28:50,440 --> 00:28:52,640 it has some of our cleanest waters. 233 00:29:04,680 --> 00:29:08,000 This is one of the reasons why Shetland 234 00:29:08,000 --> 00:29:11,320 is our main stronghold for otters. 235 00:29:19,200 --> 00:29:24,520 More than 1,000 live along its 1,600 miles of undisturbed coastline. 236 00:29:34,600 --> 00:29:38,600 Shetland's isolation and its relative lack of pollution 237 00:29:38,600 --> 00:29:40,840 suits these animals very well. 238 00:29:43,480 --> 00:29:47,040 Elsewhere, most live in or beside rivers, 239 00:29:47,040 --> 00:29:51,000 but here they spend much of their time in the sea. 240 00:29:59,880 --> 00:30:02,280 Each has its own territory 241 00:30:02,280 --> 00:30:05,920 and knows where its prey is likely to be hiding. 242 00:30:08,840 --> 00:30:13,520 But the waters in which they spend so much of their time are chilly, 243 00:30:13,520 --> 00:30:17,600 and otters need a lot of food to keep themselves warm. 244 00:30:25,080 --> 00:30:28,200 They can hold their breath for up to 90 seconds.. 245 00:30:30,440 --> 00:30:34,280 ..and reach hunting grounds as deep as ten metres. 246 00:30:46,200 --> 00:30:51,640 In summer, the waters teem with small fish, such as eelpout, 247 00:30:51,640 --> 00:30:56,240 which are easy to catch and are excellent food for the cubs. 248 00:31:07,760 --> 00:31:11,560 Little wonder that Shetland has the greatest density of otters 249 00:31:11,560 --> 00:31:13,560 anywhere in Europe. 250 00:31:21,720 --> 00:31:25,760 Otters are not the only stars in Shetland's natural history. 251 00:31:28,560 --> 00:31:33,200 Around its coast are habitats of global importance. 252 00:31:33,200 --> 00:31:35,760 Forests of kelp. 253 00:31:39,520 --> 00:31:42,720 They are among the thickest and most vigorous of their kind 254 00:31:42,720 --> 00:31:44,840 in Britain and Ireland, 255 00:31:44,840 --> 00:31:48,440 with individuals growing to over two metres tall. 256 00:31:52,600 --> 00:31:55,480 Like the seagrass, this underwater forest 257 00:31:55,480 --> 00:31:57,920 captures great quantities of carbon... 258 00:32:00,120 --> 00:32:03,520 ..and provides a home for a wide range of animals. 259 00:32:07,320 --> 00:32:10,320 One type of kelp here, the furbellow, 260 00:32:10,320 --> 00:32:13,320 has an especially feisty resident. 261 00:32:15,440 --> 00:32:20,880 Its hollow base is the favourite home of clingfish. 262 00:32:27,120 --> 00:32:30,160 This minute two-centimetre-long male 263 00:32:30,160 --> 00:32:34,120 has been left by his female to look after the eggs. 264 00:32:35,880 --> 00:32:40,840 Hundreds of them are glued to the interior of a furbellow's stem... 265 00:32:43,880 --> 00:32:46,240 ..and they're almost ready to hatch. 266 00:32:49,960 --> 00:32:52,840 It's quite a responsibility for him. 267 00:32:54,760 --> 00:32:59,320 All day long, he fans fresh, oxygen-rich sea water 268 00:32:59,320 --> 00:33:01,320 across the eggs. 269 00:33:05,080 --> 00:33:07,240 He inspects them regularly 270 00:33:07,240 --> 00:33:10,960 and quickly removes any that are infertile or dead. 271 00:33:15,600 --> 00:33:18,920 But his nursery is under attack. 272 00:33:33,160 --> 00:33:36,560 Sea urchins are devouring the furbellow. 273 00:33:41,840 --> 00:33:45,880 Their powerful jaws are destroying the clingfish's home. 274 00:33:50,320 --> 00:33:55,440 His babies are under threat, still stuck to the walls of their nursery. 275 00:33:59,240 --> 00:34:01,440 There is no escape. 276 00:34:04,880 --> 00:34:07,440 Their tiny father takes action. 277 00:34:11,600 --> 00:34:14,920 He tries to drive the urchins away by beating his tail. 278 00:34:18,240 --> 00:34:20,320 But it makes little difference. 279 00:34:21,640 --> 00:34:24,040 Time for another strategy. 280 00:34:25,880 --> 00:34:28,720 The urchins are covered in sharp spines... 281 00:34:30,120 --> 00:34:35,000 ..so the brave little father nips the urchins' sensitive tubed feet. 282 00:34:43,720 --> 00:34:49,600 Finally, the urchins give up and go in search of easier meals. 283 00:34:52,840 --> 00:34:56,720 The little male clingfish has saved his young. 284 00:35:05,240 --> 00:35:08,240 He is part of a crucial community 285 00:35:08,240 --> 00:35:12,680 that maintains the balance in this marine rainforest. 286 00:35:24,640 --> 00:35:28,080 At the height of summer, the power of the sun combines 287 00:35:28,080 --> 00:35:31,200 with the stirring action of the tides and the waves... 288 00:35:32,720 --> 00:35:34,800 ..and the ocean blooms. 289 00:35:37,360 --> 00:35:39,440 The creators of these blooms 290 00:35:39,440 --> 00:35:43,080 are myriads of floating, microscopic algae. 291 00:35:44,800 --> 00:35:49,080 They are the basis of the entire food chain in the open ocean. 292 00:35:50,520 --> 00:35:55,720 And when conditions are right, they multiply at an astonishing rate. 293 00:35:58,280 --> 00:36:01,440 Their repeated blooms are one of the main reasons 294 00:36:01,440 --> 00:36:05,200 why the seas around Britain and Ireland are so productive. 295 00:36:08,800 --> 00:36:14,840 The floating plants support a great community of tiny floating animals, 296 00:36:14,840 --> 00:36:16,960 the zooplankton. 297 00:36:18,720 --> 00:36:24,080 Tiny creatures that drift in great clouds driven by the ocean currents. 298 00:36:25,760 --> 00:36:30,120 Among them are copepods, tiny crustaceans 299 00:36:30,120 --> 00:36:34,240 that feed on the microscopic algae floating alongside them. 300 00:36:36,160 --> 00:36:38,440 The rest are mainly predators. 301 00:36:42,840 --> 00:36:45,160 Many of these are also tiny. 302 00:36:46,440 --> 00:36:50,320 The larvae of bottom-living animals like lobsters and crabs, 303 00:36:50,320 --> 00:36:53,360 some only 5mm long. 304 00:36:57,560 --> 00:36:59,640 There are also sea gooseberries, 305 00:36:59,640 --> 00:37:02,480 which propel themselves through the water 306 00:37:02,480 --> 00:37:05,280 with rows of pulsating bristles. 307 00:37:09,400 --> 00:37:13,560 They may look fragile, but they are surprisingly effective hunters. 308 00:37:19,160 --> 00:37:22,320 They extend long, thread-like tentacles. 309 00:37:26,400 --> 00:37:31,840 Other drifters that get entangled are reeled-in and eaten. 310 00:37:37,160 --> 00:37:39,840 The sea gooseberries themselves, of course, 311 00:37:39,840 --> 00:37:43,240 are also prey for larger predators... 312 00:37:44,720 --> 00:37:47,320 ..such as the melon comb jelly. 313 00:38:13,840 --> 00:38:17,200 It has a particularly large mouth. 314 00:38:24,560 --> 00:38:27,640 When it opens it, the suction it creates 315 00:38:27,640 --> 00:38:30,480 pulls its prey straight into its stomach. 316 00:38:38,200 --> 00:38:40,680 Despite the richness of our seas, 317 00:38:40,680 --> 00:38:45,440 climate change is seriously reducing the amount of zooplankton. 318 00:38:48,080 --> 00:38:52,280 And this has an effect on the entire marine food chain, 319 00:38:52,280 --> 00:38:55,480 right up to real giants. 320 00:39:00,720 --> 00:39:06,160 The largest fish in our waters is as long as a double-decker bus. 321 00:39:09,760 --> 00:39:11,640 The basking shark. 322 00:39:15,440 --> 00:39:18,800 It uses special sieve-like structures on its gills 323 00:39:18,800 --> 00:39:21,520 to filter out the zooplankton. 324 00:39:24,080 --> 00:39:27,040 And they feed on nothing else. 325 00:39:29,640 --> 00:39:35,920 In summer, these giants come close to the coast all around our isles. 326 00:39:47,960 --> 00:39:50,160 They're normally solitary, 327 00:39:50,160 --> 00:39:53,840 but when the plankton reaches the peak of its abundance, 328 00:39:53,840 --> 00:39:56,720 the sharks come together. 329 00:40:03,600 --> 00:40:05,720 They swim in formation. 330 00:40:05,720 --> 00:40:10,720 Plankton that escapes one mouth will be scooped-up by the next. 331 00:40:17,880 --> 00:40:20,360 In just a few special places 332 00:40:20,360 --> 00:40:23,840 along the western coasts of Britain and Ireland, 333 00:40:23,840 --> 00:40:29,160 basking sharks gather in large numbers to feed and breed. 334 00:40:35,600 --> 00:40:38,240 Thousands find their way here each year... 335 00:40:39,800 --> 00:40:42,320 ..a major part of the global population. 336 00:40:54,120 --> 00:40:57,720 Plankton feeders come in all sizes. 337 00:41:01,720 --> 00:41:05,200 Sand eels are only 30 centimetres long, 338 00:41:05,200 --> 00:41:08,360 but they occur in vast shoals. 339 00:41:13,360 --> 00:41:17,280 Like so many species, overfishing and warming seas 340 00:41:17,280 --> 00:41:19,840 have drastically reduced their numbers. 341 00:41:22,080 --> 00:41:26,960 They are essential prey for a wide range of top predators. 342 00:41:32,760 --> 00:41:37,720 Dolphins scour vast areas of the open ocean to track down the shoals. 343 00:41:41,880 --> 00:41:45,920 And following the dolphins comes an ocean legend... 344 00:41:47,760 --> 00:41:49,520 ..bluefin tuna. 345 00:41:52,440 --> 00:41:54,600 Weighing up to 700 kilos 346 00:41:54,600 --> 00:41:57,680 and with a top speed of more than 40mph, 347 00:41:57,680 --> 00:42:02,960 these powerful predators can make quick work of the shoal. 348 00:42:05,480 --> 00:42:09,880 Bluefins have been absent from our waters for more than 50 years. 349 00:42:13,400 --> 00:42:16,160 And they have only recently returned. 350 00:42:18,720 --> 00:42:20,720 If they are to stay, 351 00:42:20,720 --> 00:42:24,160 the overfishing of our seas will have to be stopped. 352 00:42:26,480 --> 00:42:28,400 In the sky above... 353 00:42:29,400 --> 00:42:33,720 ..gannets, looking for fish such as mackerel and herring. 354 00:42:43,440 --> 00:42:46,280 They hit the water at over 60mph. 355 00:42:52,240 --> 00:42:54,320 The impact is enormous. 356 00:42:56,920 --> 00:43:00,120 To avoid breaking their wings, they fold them back 357 00:43:00,120 --> 00:43:03,160 and turn themselves into streamlined arrows. 358 00:43:23,520 --> 00:43:27,520 65% of the world's population of northern gannets 359 00:43:27,520 --> 00:43:30,600 find their food in our seas. 360 00:43:49,520 --> 00:43:53,160 But perhaps the bird that depends most on the still-rich waters 361 00:43:53,160 --> 00:43:57,920 around Britain and Ireland is the Manx shearwater. 362 00:44:05,080 --> 00:44:07,560 Every year, our coasts are visited 363 00:44:07,560 --> 00:44:11,800 by almost the entire global population of this sea bird. 364 00:44:16,320 --> 00:44:19,880 Here in Cardigan Bay off central Wales, 365 00:44:19,880 --> 00:44:22,920 they gather in their thousands, 366 00:44:22,920 --> 00:44:26,480 attracted by the richness of our seas. 367 00:44:36,400 --> 00:44:41,120 Each summer, 350,000 pairs all return 368 00:44:41,120 --> 00:44:44,800 to this tiny island of Skomer off the Pembrokeshire coast. 369 00:44:44,800 --> 00:44:48,480 This is the largest breeding colony in the world 370 00:44:48,480 --> 00:44:52,000 and most of the island is honeycombed with their burrows. 371 00:44:52,000 --> 00:44:55,000 Tonight, under the cover of darkness, 372 00:44:55,000 --> 00:44:58,040 their chicks are starting to leave these burrows 373 00:44:58,040 --> 00:45:00,120 for the very first time. 374 00:45:03,120 --> 00:45:07,520 Watching them do so is an unforgettable privilege. 375 00:45:12,280 --> 00:45:16,440 This young bird has just emerged from its nest hole, 376 00:45:16,440 --> 00:45:18,720 maybe for the first time. 377 00:45:20,400 --> 00:45:24,440 It's about to make the most important journey of its life. 378 00:45:26,000 --> 00:45:30,400 And it needs to get every inch of altitude before it takes off. 379 00:45:32,040 --> 00:45:34,000 I can just see beyond me... 380 00:45:35,200 --> 00:45:37,160 ..there are more of them. 381 00:45:38,520 --> 00:45:41,280 One, two, three, four. 382 00:45:44,840 --> 00:45:47,240 It's just exercising its wings... 383 00:45:49,080 --> 00:45:52,040 ..in preparation for this extraordinary flight... 384 00:45:53,320 --> 00:45:58,040 ..which will take it 6,000 miles across the oceans 385 00:45:58,040 --> 00:46:02,080 to South America, to Brazil and Argentina. 386 00:46:03,200 --> 00:46:06,120 And then, after some four years, 387 00:46:06,120 --> 00:46:10,960 once again it will set out on a long oceanic journey, 388 00:46:10,960 --> 00:46:16,880 a further 6,000 miles back to this one small island of Skomer. 389 00:46:18,520 --> 00:46:20,400 Are you going to go? 390 00:46:20,400 --> 00:46:23,800 It's hesitating and who can blame it? 391 00:46:25,120 --> 00:46:29,600 An enormous journey awaits it once it takes off from here. 392 00:46:31,600 --> 00:46:35,840 This is the headquarters of this astonishing species 393 00:46:36,960 --> 00:46:39,400 ..and we are its custodians. 394 00:46:40,760 --> 00:46:42,440 Come along. 395 00:46:42,440 --> 00:46:44,560 Come along. Come along. 396 00:46:45,760 --> 00:46:47,600 Are you about to take off? 397 00:46:50,960 --> 00:46:52,560 Good luck! 398 00:46:54,000 --> 00:46:55,440 HE CHUCKLES 399 00:46:56,440 --> 00:46:58,840 What an astonishment. 400 00:47:11,680 --> 00:47:14,720 A lot has changed in my lifetime 401 00:47:14,720 --> 00:47:17,600 and today the wildlife we still have 402 00:47:17,600 --> 00:47:20,520 faces greater threats than ever before. 403 00:47:20,520 --> 00:47:24,320 Our sea birds remind us that here in Britain and Ireland 404 00:47:24,320 --> 00:47:28,640 we are very fortunate to have some of nature's greatest spectacles 405 00:47:28,640 --> 00:47:30,680 right on our doorstep. 406 00:47:31,760 --> 00:47:33,840 Because this is our home, 407 00:47:33,840 --> 00:47:38,360 it can only be our responsibility to restore and protect our wildlife. 408 00:47:38,360 --> 00:47:43,400 Perhaps you can be the first to pass these wild isles 409 00:47:43,400 --> 00:47:48,560 on to the next generation in better shape than you inherited them. 410 00:48:20,160 --> 00:48:25,120 From the Isles of Scilly in the south, to Shetland in the north, 411 00:48:25,120 --> 00:48:29,520 the ocean team spent 300 days filming the marine wildlife 412 00:48:29,520 --> 00:48:32,200 of the British Isles as never before. 413 00:48:33,600 --> 00:48:35,680 They captured new behaviours, 414 00:48:35,680 --> 00:48:39,320 experienced the worst of the Atlantic weather, 415 00:48:39,320 --> 00:48:43,720 and witnessed intimate moments in the lives of our ocean wildlife. 416 00:48:45,000 --> 00:48:49,640 Doug Anderson, is one of the world's leading underwater camera operators. 417 00:48:49,640 --> 00:48:52,040 He's worked all over the planet, 418 00:48:52,040 --> 00:48:56,880 filming some of the ocean's greatest spectacles and largest inhabitants. 419 00:48:58,240 --> 00:49:02,000 And for this series, he filmed the majority of the ocean episode. 420 00:49:03,680 --> 00:49:07,600 His passion for the underwater world began on the Isle of Arran, 421 00:49:07,600 --> 00:49:10,080 off the west coast of Scotland. 422 00:49:10,080 --> 00:49:13,120 My first underwater experience was in Lamlash Bay 423 00:49:13,120 --> 00:49:15,360 in front of my grandparents' house 424 00:49:15,360 --> 00:49:18,400 and it is burnt into my memory. 425 00:49:18,400 --> 00:49:23,400 My dad had made me a wet suit and I remember putting my face underwater 426 00:49:23,400 --> 00:49:29,280 and just being blown away but the wildness of it. 427 00:49:29,280 --> 00:49:32,200 You know, there were crabs and little fish 428 00:49:32,200 --> 00:49:34,240 and it felt like a wild place. 429 00:49:34,240 --> 00:49:36,160 I remember lifting my head up 430 00:49:36,160 --> 00:49:38,800 and looking over my shoulder back at the village - 431 00:49:38,800 --> 00:49:41,080 there was, like, the policeman doing his round, 432 00:49:41,080 --> 00:49:43,640 and people going to the shop and I was like, 433 00:49:43,640 --> 00:49:48,000 "Oh, the ocean is a wild place and behind me is what people do." 434 00:49:48,000 --> 00:49:50,360 And I never recovered. 435 00:49:54,160 --> 00:49:56,400 After learning to dive, 436 00:49:56,400 --> 00:49:59,360 Doug's passion for the underwater world 437 00:49:59,360 --> 00:50:02,200 took him on a journey far from home. 438 00:50:02,200 --> 00:50:05,200 I eventually got a job on a series called The Blue Planet, 439 00:50:05,200 --> 00:50:07,240 back in the mid-'90s. 440 00:50:07,240 --> 00:50:09,960 And then just found myself on plane out to the Azores. 441 00:50:09,960 --> 00:50:13,200 Yeah, I was, like, 27 years old, and that was the start. 442 00:50:14,560 --> 00:50:17,280 Until now, he's never had the chance to show 443 00:50:17,280 --> 00:50:20,000 what the British Isles has to offer. 444 00:50:20,000 --> 00:50:23,760 On the Wild Isles project, it just felt like an amazing opportunity 445 00:50:23,760 --> 00:50:27,040 and responsibility to take everything I've learned 446 00:50:27,040 --> 00:50:30,160 in 25 years of working all over the planet, 447 00:50:30,160 --> 00:50:33,680 and just applying all of that to here. 448 00:50:33,680 --> 00:50:36,600 Although they might be easier to reach, 449 00:50:36,600 --> 00:50:38,880 our waters have their own challenges. 450 00:50:40,760 --> 00:50:42,800 This project, in many ways, 451 00:50:42,800 --> 00:50:45,680 has been the hardest professional experience of my life. 452 00:50:45,680 --> 00:50:48,960 Everything that you do on the ocean in the North Atlantic is tough. 453 00:50:48,960 --> 00:50:51,400 We can have four seasons in a day. 454 00:50:52,560 --> 00:50:55,280 This unpredictability makes filming in our seas 455 00:50:55,280 --> 00:50:57,320 a matter of boom or bust. 456 00:50:58,920 --> 00:51:01,160 The team must be on constant standby 457 00:51:01,160 --> 00:51:04,200 to mobilise quickly when conditions are right. 458 00:51:06,120 --> 00:51:09,160 In Shetland, they're heading for the seabed. 459 00:51:11,760 --> 00:51:13,880 To record life down here, 460 00:51:13,880 --> 00:51:17,600 Doug has designed and built his own bespoke underwater tripod. 461 00:51:19,400 --> 00:51:22,160 High-powered lights illuminate the seafloor... 462 00:51:23,120 --> 00:51:26,040 ..and weights stabilise the rig, 463 00:51:26,040 --> 00:51:30,320 allowing Doug to film a time-lapse of these slow-moving creatures, 464 00:51:30,320 --> 00:51:35,480 revealing a world that few people will ever see in actuality. 465 00:51:37,000 --> 00:51:40,760 Below the kelp, Doug takes his design a step further - 466 00:51:40,760 --> 00:51:45,280 a motion-controlled slider for tracking timelapses. 467 00:51:45,280 --> 00:51:49,320 Now, he can move the camera with pinpoint accuracy, 468 00:51:49,320 --> 00:51:52,680 revealing how urchins travel through this marine forest. 469 00:51:54,120 --> 00:51:56,800 A shot that's taken months of preparation. 470 00:52:00,000 --> 00:52:03,160 But not everything in our oceans is as slow-moving. 471 00:52:04,160 --> 00:52:06,200 Off the coast of Cornwall, 472 00:52:06,200 --> 00:52:09,720 the team are chasing one of the ocean's fastest inhabitants, 473 00:52:09,720 --> 00:52:11,600 bluefin tuna. 474 00:52:12,640 --> 00:52:15,800 They have only retuned to our waters in the last few years. 475 00:52:17,040 --> 00:52:19,480 We've got all the ingredients that we need here. 476 00:52:19,480 --> 00:52:21,480 We've got dolphins, we've got tuna, 477 00:52:21,480 --> 00:52:23,840 there's gannets here, and shearwaters. 478 00:52:23,840 --> 00:52:26,840 But we need it to come together into something that we can film, 479 00:52:26,840 --> 00:52:28,640 and that's a bait ball. 480 00:52:28,640 --> 00:52:31,520 So it has to be a patch of fish jammed up against the surface 481 00:52:31,520 --> 00:52:34,320 in reasonable visibility to make it work, so... 482 00:52:35,800 --> 00:52:37,440 ..fingers crossed. 483 00:52:38,720 --> 00:52:40,800 Bait balls don't last long. 484 00:52:40,800 --> 00:52:44,120 They can be over in a matter of minutes. 485 00:52:44,120 --> 00:52:47,280 So to film tuna hunting, speed is everything. 486 00:52:49,040 --> 00:52:53,120 Radio call from one of our contacts, so we screamed down there, 487 00:52:53,120 --> 00:52:57,560 only to discover we were just a few moments too late. 488 00:52:57,560 --> 00:53:01,880 Which is really frustrating. We've got a really fast boat. 489 00:53:06,880 --> 00:53:11,240 This is so new, this set-up here, these bait fish coming here. 490 00:53:11,240 --> 00:53:13,440 It's five years, so we're just... 491 00:53:13,440 --> 00:53:16,800 Everyone's just working it out and it seems like we're not alone 492 00:53:16,800 --> 00:53:20,040 cos it's like the dolphin and the tuna are just beginning to find it 493 00:53:20,040 --> 00:53:22,080 and exploit the resource as well. 494 00:53:23,280 --> 00:53:26,400 The team use a drone to help locate the tuna 495 00:53:26,400 --> 00:53:29,000 before the bait balls disappear. 496 00:53:31,120 --> 00:53:33,360 The exciting thing is, this is England. 497 00:53:33,360 --> 00:53:35,960 We've got literally Falmouth right there 498 00:53:35,960 --> 00:53:39,800 and we've got these crazy pods of common dolphins rolling through 499 00:53:39,800 --> 00:53:42,560 and there's bluefin showing every now and then. 500 00:53:42,560 --> 00:53:44,680 It's an amazing kind of ocean scene. 501 00:53:44,680 --> 00:53:47,360 Although it looks good from the air, 502 00:53:47,360 --> 00:53:51,840 poor visibility underwater prevents Doug from getting a clear shot. 503 00:53:51,840 --> 00:53:56,440 Yeah, a total glimpse, just like the briefest of moment. 504 00:53:56,440 --> 00:53:58,600 Pretty green water, I just get in, 505 00:53:58,600 --> 00:54:01,440 and they just come through and just roll through. 506 00:54:03,120 --> 00:54:06,800 In the hope of finding clearer water, the team change location. 507 00:54:08,040 --> 00:54:09,920 We're further down the coast. 508 00:54:09,920 --> 00:54:12,480 We're going to be working further offshore, 509 00:54:12,480 --> 00:54:16,000 and we're going to be trying to join the blue water with the bluefin. 510 00:54:16,000 --> 00:54:19,640 If a big patch of pilchards on the surface or mackerel comes together, 511 00:54:19,640 --> 00:54:22,080 then come away with what we want from this. 512 00:54:23,400 --> 00:54:25,880 We have tuna, they're all over the place just now. 513 00:54:25,880 --> 00:54:29,040 We just need to wait for this sort of pot to boil, you know. 514 00:54:29,040 --> 00:54:31,440 For the bait to come together into a lump 515 00:54:31,440 --> 00:54:35,000 for long enough, for it to go static so that we can get in and film it. 516 00:54:36,720 --> 00:54:38,480 The plan works! 517 00:54:38,480 --> 00:54:42,080 The team finally get the conditions they have been seeking for so long. 518 00:54:42,080 --> 00:54:45,800 To actually see a bluefin tuna underwater in England 519 00:54:45,800 --> 00:54:48,880 is just unbelievable. 520 00:54:50,640 --> 00:54:53,120 The return of bluefin tuna to our waters 521 00:54:53,120 --> 00:54:56,080 is a sign that their population is recovering. 522 00:54:56,080 --> 00:54:59,880 But it's still a fraction of what their numbers could be. 523 00:55:03,360 --> 00:55:06,800 Since Doug left Arran over two decades ago, 524 00:55:06,800 --> 00:55:10,560 the coastal community, including his family, 525 00:55:10,560 --> 00:55:14,280 created Scotland's first marine No Take Zone. 526 00:55:16,920 --> 00:55:22,920 Since its creation in Lamlash Bay, biodiversity has increased fourfold. 527 00:55:24,640 --> 00:55:29,120 But it's one of just a handful of No Take Zones around our wild isles, 528 00:55:29,120 --> 00:55:33,400 that combined, cover less than 1% of our sea. 529 00:55:33,400 --> 00:55:35,840 The abundance of life within them 530 00:55:35,840 --> 00:55:38,960 spills out into the surrounding waters, 531 00:55:38,960 --> 00:55:42,560 enriching and strengthening the wider marine environment 532 00:55:42,560 --> 00:55:46,400 The way to get British seas back is to allow large areas 533 00:55:46,400 --> 00:55:49,040 to return to a natural state, 534 00:55:49,040 --> 00:55:54,320 and maintain those very highly protected areas for a long time. 535 00:55:55,400 --> 00:55:58,560 For Doug, celebrating the beauty of British waters 536 00:55:58,560 --> 00:56:01,720 has been a chance for him to give something back. 537 00:56:03,760 --> 00:56:07,040 If I can play a tiny part about providing the visuals 538 00:56:07,040 --> 00:56:10,480 to allow that conversation to happen in a meaningful way, 539 00:56:10,480 --> 00:56:13,520 for people on all sides of the argument 540 00:56:13,520 --> 00:56:17,760 to imagine what lies beneath those grey waves, 541 00:56:17,760 --> 00:56:21,320 then I think it would be an extraordinary thing. 542 00:56:30,360 --> 00:56:33,440 The Open University has produced a free poster 543 00:56:33,440 --> 00:56:38,320 exploring our Wild Isles and their diverse habitat and species. 544 00:56:38,320 --> 00:56:41,360 Order your copy by calling... 545 00:56:44,120 --> 00:56:46,160 ..or go to... 546 00:56:49,440 --> 00:56:51,120 ..and follow the links 547 00:56:51,120 --> 00:56:53,000 to the Open University. 548 00:56:53,000 --> 00:56:56,840 If you'd like to play your part in restoring our Wild Isles 549 00:56:56,840 --> 00:56:59,680 and learn more about what you can do to help, 550 00:56:59,680 --> 00:57:03,160 just search Wild Isles on the BBC website.