1 00:00:34,000 --> 00:00:39,840 Here in Britain and Ireland, we have some of the richest seas in Europe. 2 00:00:40,960 --> 00:00:45,519 Our varied coastline, if you include all the many offshore islands, 3 00:00:45,520 --> 00:00:48,159 is over 22,000 miles long, 4 00:00:48,160 --> 00:00:52,160 and none of us live more than 70 miles away from the sea. 5 00:00:53,120 --> 00:00:56,679 Yet few of us have seen the wonders beyond the beach 6 00:00:56,680 --> 00:00:58,679 and beneath the waves. 7 00:00:58,680 --> 00:01:01,039 In this episode, we will take you 8 00:01:01,040 --> 00:01:03,519 from the most southerly point of the 9 00:01:03,520 --> 00:01:06,199 United Kingdom to the furthest north, 10 00:01:06,200 --> 00:01:09,719 to explain why our seas can be so productive 11 00:01:09,720 --> 00:01:13,080 and reveal the threats that they face today. 12 00:01:28,480 --> 00:01:33,279 Every winter, a warm ocean current, the gulf stream, 13 00:01:33,280 --> 00:01:36,960 drives huge storms across the Atlantic... 14 00:01:39,120 --> 00:01:44,280 ..away from the Caribbean and straight towards our shores. 15 00:01:48,920 --> 00:01:54,040 There, every winter, they batter the west coasts of our islands. 16 00:02:03,320 --> 00:02:06,839 Waves with energy built up across an entire ocean 17 00:02:06,840 --> 00:02:09,280 are hurled at our coasts. 18 00:02:13,640 --> 00:02:16,559 Walls of water more than ten metres tall 19 00:02:16,560 --> 00:02:19,200 crash repeatedly onto the rocks. 20 00:02:32,280 --> 00:02:35,039 And as the water at depth is churned, 21 00:02:35,040 --> 00:02:38,480 it brings nutrients up towards the surface. 22 00:02:44,240 --> 00:02:48,599 These nutrients, combined with the warmth of the gulf stream, 23 00:02:48,600 --> 00:02:52,759 are the reason why marine life here proliferates 24 00:02:52,760 --> 00:02:56,080 with such extraordinary richness and variety. 25 00:03:23,200 --> 00:03:25,239 Each year, in autumn, 26 00:03:25,240 --> 00:03:29,480 evidence of this marine abundance appears on land. 27 00:03:34,480 --> 00:03:39,760 13,000 grey seals haul out on Blakeney Point in Norfolk. 28 00:03:41,200 --> 00:03:44,360 It's the largest seal colony in England. 29 00:03:46,840 --> 00:03:50,679 Females, having spent most of the year feeding in our rich waters, 30 00:03:50,680 --> 00:03:53,200 are preparing to produce their young. 31 00:03:54,800 --> 00:03:57,600 Newly born, the pups are helpless... 32 00:04:00,240 --> 00:04:04,320 ..and for their first few weeks, entirely dependent on their mothers. 33 00:04:06,000 --> 00:04:09,040 Seal milk is more than 50% fat... 34 00:04:10,000 --> 00:04:12,960 ..and the pups put on two kilos a day. 35 00:04:16,680 --> 00:04:20,440 At first, parent and pup are inseparable. 36 00:04:24,560 --> 00:04:29,480 But then, after a few days, the youngsters start to explore. 37 00:04:31,800 --> 00:04:34,759 Other females don't tolerate the appearance 38 00:04:34,760 --> 00:04:37,480 of unrelated pups on their patch. 39 00:04:57,000 --> 00:05:00,040 Posing an even greater threat than the females... 40 00:05:01,000 --> 00:05:02,840 ..are the males. 41 00:05:10,320 --> 00:05:13,720 Three metres long and weighing 350 kilos... 42 00:05:15,520 --> 00:05:18,080 ..they have come here to mate. 43 00:05:21,920 --> 00:05:25,199 They know that soon after the pups are born, 44 00:05:25,200 --> 00:05:29,400 the females will become sexually receptive once again. 45 00:05:33,360 --> 00:05:36,599 This big male tries to control all the females 46 00:05:36,600 --> 00:05:38,840 on this stretch of the beach. 47 00:05:42,400 --> 00:05:44,920 But he has a rival. 48 00:05:52,640 --> 00:05:54,319 ROARS 49 00:05:54,320 --> 00:05:57,719 The big male warns off the challenger, 50 00:05:57,720 --> 00:06:00,199 but the intruder takes no notice. 51 00:06:00,200 --> 00:06:02,040 ROARS 52 00:06:06,840 --> 00:06:09,160 There's only one way to settle this. 53 00:06:11,160 --> 00:06:12,800 Violence. 54 00:06:24,280 --> 00:06:26,199 When the males fight, 55 00:06:26,200 --> 00:06:29,080 they take no notice of any pup that gets in their way. 56 00:06:31,920 --> 00:06:33,759 GRUNTS 57 00:06:33,760 --> 00:06:35,760 The pup's mother intervenes... 58 00:06:40,280 --> 00:06:43,000 ..allowing her pup to wriggle away. 59 00:06:49,680 --> 00:06:52,920 Finally, the battle turns. 60 00:06:57,080 --> 00:07:00,680 The intruder starts to retreat towards the sea. 61 00:07:04,200 --> 00:07:07,280 Now, the smaller males join the chase. 62 00:07:20,360 --> 00:07:24,320 The big male has retained his right to mate. 63 00:07:29,360 --> 00:07:33,399 Despite these battles, Blakeney Point still provides the pups 64 00:07:33,400 --> 00:07:35,600 with an excellent start in life. 65 00:07:37,240 --> 00:07:39,840 5,000 are born here each year. 66 00:07:43,840 --> 00:07:47,879 A remarkable 40% of the world population of grey seals 67 00:07:47,880 --> 00:07:50,320 lives around the British Isles. 68 00:07:52,040 --> 00:07:55,480 Impressive evidence of the richness of our seas. 69 00:08:00,680 --> 00:08:04,640 Beneath the surface, that wealth is very evident. 70 00:08:15,400 --> 00:08:18,799 Cold, nutrient-rich currents from the north 71 00:08:18,800 --> 00:08:22,279 mingle with the warm waters of the gulf stream, 72 00:08:22,280 --> 00:08:26,560 and support an astonishing variety of plants and animals. 73 00:08:31,360 --> 00:08:34,720 There are more than 10,000 different species here. 74 00:09:09,520 --> 00:09:13,719 The effect of the gulf stream is felt most keenly 75 00:09:13,720 --> 00:09:17,920 at our southernmost point, around the Isles of Scilly. 76 00:09:21,240 --> 00:09:24,639 Here grows one of the biggest stretches of seagrass 77 00:09:24,640 --> 00:09:28,280 to be found anywhere in British and Irish waters. 78 00:09:31,000 --> 00:09:35,399 Seagrass is important globally because it collects carbon 79 00:09:35,400 --> 00:09:39,560 up to 35 times faster than a tropical rainforest. 80 00:09:42,560 --> 00:09:46,239 But we have lost nearly 90% of our seagrass, 81 00:09:46,240 --> 00:09:50,400 mainly because of pollution and disturbance of the seabed. 82 00:09:53,800 --> 00:09:56,719 Nonetheless, these marine meadows 83 00:09:56,720 --> 00:10:00,280 are home to a wide variety of small animals. 84 00:10:01,720 --> 00:10:06,240 Including this perhaps somewhat surprising one. 85 00:10:11,120 --> 00:10:13,760 A spiny seahorse. 86 00:10:14,800 --> 00:10:18,320 One of just two species of seahorse that live in our waters. 87 00:10:24,120 --> 00:10:27,800 They thrive in the warmth brought by the gulf stream. 88 00:10:35,480 --> 00:10:37,519 The seagrass provides them 89 00:10:37,520 --> 00:10:40,680 with the seclusion they prefer for their courtship. 90 00:10:53,920 --> 00:10:57,479 A crucial part of their underwater dance 91 00:10:57,480 --> 00:11:01,600 involves a gentle entwining of their tails. 92 00:11:05,320 --> 00:11:08,999 It's behaviour you might think to be more typical 93 00:11:09,000 --> 00:11:12,480 of the warm, balmy waters of the Mediterranean. 94 00:11:21,960 --> 00:11:24,199 And there is another creature 95 00:11:24,200 --> 00:11:27,480 that is also more usually found in warmer waters. 96 00:11:32,200 --> 00:11:34,240 The common cuttlefish. 97 00:11:37,640 --> 00:11:41,840 It's the most northerly of all cuttlefish species. 98 00:11:44,160 --> 00:11:48,079 This pregnant female, about the size of a rugby football, 99 00:11:48,080 --> 00:11:52,760 is being guarded by a male as she prepares to lay her eggs. 100 00:11:55,280 --> 00:11:58,239 First, she cleans her chosen site 101 00:11:58,240 --> 00:12:01,880 by squirting jets of water over the seaweed. 102 00:12:05,200 --> 00:12:08,039 Several dozen black eggs are already here, 103 00:12:08,040 --> 00:12:10,520 having been laid the previous day. 104 00:12:21,600 --> 00:12:23,680 And now she adds more... 105 00:12:24,640 --> 00:12:29,440 ..one by one, until there are up to 3,000 or so. 106 00:12:38,920 --> 00:12:40,840 A month later... 107 00:12:43,680 --> 00:12:48,120 ..during the night, the eggs start to hatch. 108 00:12:54,440 --> 00:12:59,840 A perfectly formed baby cuttlefish, no larger than a pea. 109 00:13:06,680 --> 00:13:08,879 Within a few weeks, 110 00:13:08,880 --> 00:13:12,399 a male has grown to a length of around six centimetres 111 00:13:12,400 --> 00:13:15,400 and is already a stealthy hunter. 112 00:13:26,160 --> 00:13:31,000 His eyesight is so sensitive that he's able to hunt by moonlight. 113 00:13:53,720 --> 00:13:56,000 But when the moon disappears... 114 00:13:58,120 --> 00:14:00,599 ..even he cannot see 115 00:14:00,600 --> 00:14:05,040 and the darkness usually brings hunting to an end. 116 00:14:09,800 --> 00:14:12,280 But on just a few nights each year... 117 00:14:13,240 --> 00:14:15,760 ..something extraordinary happens. 118 00:14:19,720 --> 00:14:26,160 Tiny light-producing algae create vast clouds of bioluminescence. 119 00:14:30,800 --> 00:14:35,880 They're stimulated to switch on by any sudden movement in the water. 120 00:14:42,400 --> 00:14:46,199 Even the slight swirl produced by a tiny crab as it breathes 121 00:14:46,200 --> 00:14:48,120 has an effect. 122 00:14:52,120 --> 00:14:54,839 The hunter must move very smoothly, 123 00:14:54,840 --> 00:14:58,000 to avoid creating a light show of his own. 124 00:15:26,200 --> 00:15:30,239 The light of the algae has enabled it to see its prey 125 00:15:30,240 --> 00:15:32,760 and so hunt throughout the night. 126 00:15:40,480 --> 00:15:44,359 A year later, the cuttlefish are fully grown 127 00:15:44,360 --> 00:15:47,880 and this male is now looking for a female. 128 00:15:51,280 --> 00:15:55,280 But the traditional breeding site is empty. 129 00:16:03,240 --> 00:16:05,840 The cuttlefish that gathered here to mate... 130 00:16:07,240 --> 00:16:09,920 ..have been caught in a fishing pot. 131 00:16:14,440 --> 00:16:18,040 They may be among the most intelligent animals in the sea... 132 00:16:19,760 --> 00:16:23,160 ..but they've been fooled by a simple trap. 133 00:16:26,560 --> 00:16:29,560 And once in it, there is no escape. 134 00:16:46,800 --> 00:16:51,320 The male outside spots a possible mate. 135 00:16:59,760 --> 00:17:01,920 But he can't reach her. 136 00:17:15,280 --> 00:17:20,119 Our cuttlefish population can tolerate some loss to fishing, 137 00:17:20,120 --> 00:17:25,279 but surely we shouldn't put pots where they habitually breed, 138 00:17:25,280 --> 00:17:28,960 and prevent them from producing their next generation 139 00:17:45,640 --> 00:17:51,760 Away from the coast, the seabed may seem barren and lifeless. 140 00:17:53,640 --> 00:17:56,440 But looks can be deceptive. 141 00:17:59,000 --> 00:18:03,839 This muddy seafloor is rich in bacteria and algae 142 00:18:03,840 --> 00:18:08,440 and provides food for one animal in particular. 143 00:18:10,160 --> 00:18:14,880 A slow-moving creature that can grow up to a length of six centimetres. 144 00:18:17,760 --> 00:18:21,040 The royal flush sea slug. 145 00:18:25,320 --> 00:18:28,520 Thousands graze the seafloor here. 146 00:18:33,120 --> 00:18:36,279 But with so much competition for the same food, 147 00:18:36,280 --> 00:18:38,520 supplies eventually run out. 148 00:18:40,280 --> 00:18:42,880 And the sea slugs have to move on... 149 00:18:43,880 --> 00:18:46,200 ..in their own strange way. 150 00:18:50,120 --> 00:18:55,280 They flap their wing-like mantles and rise up from the seabed. 151 00:19:01,640 --> 00:19:06,520 Drifting on the slow current, they can travel for miles. 152 00:19:26,400 --> 00:19:31,680 This extraordinary mass migration has never been filmed before. 153 00:19:47,160 --> 00:19:51,360 Eventually, they reach new feeding grounds. 154 00:20:04,480 --> 00:20:09,280 And now they can start hoovering the seabed once more. 155 00:20:19,120 --> 00:20:21,959 As spring turns to summer, 156 00:20:21,960 --> 00:20:27,319 another very different migration begins all along the south coast, 157 00:20:27,320 --> 00:20:29,800 and for a very different reason. 158 00:20:33,760 --> 00:20:36,440 A young female spider crab. 159 00:20:39,480 --> 00:20:44,640 She is searching these sandy plains for others of her own kind. 160 00:20:54,680 --> 00:20:57,439 Spider crabs are normally solitary, 161 00:20:57,440 --> 00:21:02,320 but now, in the summer, they start to assemble into groups. 162 00:21:05,800 --> 00:21:10,680 And then, when there are enough of them, they start to travel. 163 00:21:20,080 --> 00:21:23,719 Together, they journey for miles across the seabed, 164 00:21:23,720 --> 00:21:27,000 all heading in the same direction. 165 00:21:40,040 --> 00:21:42,079 Groups join together 166 00:21:42,080 --> 00:21:47,160 and the travellers become one great horde, several-thousand strong. 167 00:21:51,840 --> 00:21:55,880 They are about to face the most dangerous time of their lives. 168 00:22:01,200 --> 00:22:06,760 They have outgrown their hard shells and must now escape from them. 169 00:22:11,560 --> 00:22:13,879 A new shell is expandable, 170 00:22:13,880 --> 00:22:17,319 but it remains soft for several hours 171 00:22:17,320 --> 00:22:21,160 and until it hardens, its owner has no defence. 172 00:22:27,280 --> 00:22:30,720 That is why they've made this journey together. 173 00:22:34,680 --> 00:22:37,640 There is safety in numbers. 174 00:22:46,600 --> 00:22:50,599 Ocean currents are one reason why our waters are so rich. 175 00:22:50,600 --> 00:22:54,840 Another is the exceptional size of our tides. 176 00:22:56,320 --> 00:22:58,399 Vast amounts of water 177 00:22:58,400 --> 00:23:01,399 are continuously transported around our islands 178 00:23:01,400 --> 00:23:03,560 by these powerful currents. 179 00:23:06,800 --> 00:23:10,319 The third biggest tidal rise and fall on the planet 180 00:23:10,320 --> 00:23:13,600 occurs in the estuary of the River Severn. 181 00:23:17,920 --> 00:23:19,799 From low tide, 182 00:23:19,800 --> 00:23:23,919 the sea level rises by as much as the height of a five-storey building 183 00:23:23,920 --> 00:23:27,680 and then falls again, twice every day. 184 00:23:31,840 --> 00:23:35,999 These huge transformations churn-up the nutrients 185 00:23:36,000 --> 00:23:38,800 and replenish the mudflats. 186 00:23:48,640 --> 00:23:51,839 Further north, on the west coast of Scotland, 187 00:23:51,840 --> 00:23:56,200 the power of our tides creates another great spectacle. 188 00:24:00,560 --> 00:24:02,999 The Corryvreckan whirlpool. 189 00:24:03,000 --> 00:24:05,440 25 metres across. 190 00:24:12,400 --> 00:24:15,480 It's the third largest whirlpool in the world. 191 00:24:21,920 --> 00:24:25,559 These powerful tidal currents mix-up the water, 192 00:24:25,560 --> 00:24:30,320 constantly bringing nutrients from the depths up to the surface layers. 193 00:24:35,840 --> 00:24:40,840 And the influence of the tides can extend right down to the seafloor. 194 00:24:45,240 --> 00:24:49,319 The animals down here thrive in these ever-moving currents. 195 00:24:49,320 --> 00:24:53,040 Every square inch is bursting with life. 196 00:25:00,000 --> 00:25:04,120 The flowing water brings a never-ending supply of food. 197 00:25:05,400 --> 00:25:10,040 Brittle stars and sea cucumbers compete to collect all they can. 198 00:25:20,560 --> 00:25:24,240 So many creatures inevitably attracts predators. 199 00:25:33,440 --> 00:25:37,360 The seven-armed starfish - half a metre across. 200 00:25:39,720 --> 00:25:43,120 The brittle stars do their best to get out of their way. 201 00:25:49,520 --> 00:25:52,839 The huge starfish feel for their prey 202 00:25:52,840 --> 00:25:55,799 using hundreds of sensitive tubed feet 203 00:25:55,800 --> 00:25:58,720 that line the underside of their arms. 204 00:26:01,200 --> 00:26:05,560 Yet, not every animal they encounter tries to escape. 205 00:26:08,640 --> 00:26:11,599 This hermit crab, with its powerful claws, 206 00:26:11,600 --> 00:26:14,160 is well able to defend itself. 207 00:26:24,480 --> 00:26:29,480 Finally, the persistent starfish find what they're looking for. 208 00:26:35,400 --> 00:26:37,520 A queen scallop. 209 00:26:41,280 --> 00:26:46,520 Its lines of simple black eyes are able to detect fast-moving threats. 210 00:26:49,040 --> 00:26:52,080 But the starfish moves quite slowly... 211 00:26:54,600 --> 00:26:57,280 ..and the scallop doesn't notice. 212 00:27:00,000 --> 00:27:03,319 Only when the scallop feels the predator's probing feet, 213 00:27:03,320 --> 00:27:05,240 does it react. 214 00:27:11,120 --> 00:27:15,360 It swims away by clapping together the two parts of its shell. 215 00:27:21,440 --> 00:27:24,479 It's a surprisingly effective technique, 216 00:27:24,480 --> 00:27:27,840 and with luck will carry the scallop to safety. 217 00:27:32,480 --> 00:27:36,160 But scallops don't have a strong sense of direction... 218 00:27:39,400 --> 00:27:42,760 ..and the starfish just keep coming. 219 00:27:46,360 --> 00:27:50,359 The starfish first pulls the scallop shell apart 220 00:27:50,360 --> 00:27:53,599 and then inserts its extendable stomach 221 00:27:53,600 --> 00:27:56,040 to digest the scallop's flesh. 222 00:27:58,720 --> 00:28:01,839 The smell of the feast drifts through the water 223 00:28:01,840 --> 00:28:03,880 and attracts scavengers. 224 00:28:07,120 --> 00:28:08,640 Whelks. 225 00:28:10,560 --> 00:28:13,000 They are the clean-up crew. 226 00:28:18,360 --> 00:28:23,360 Tidal beds like these can easily be destroyed by bottom-trawling. 227 00:28:25,240 --> 00:28:27,999 Protecting those that survive is essential 228 00:28:28,000 --> 00:28:31,080 if we are to preserve the richness of our seas. 229 00:28:37,880 --> 00:28:42,039 100 miles from mainland Scotland lies Shetland, 230 00:28:42,040 --> 00:28:44,920 the most northerly part of the British Isles. 231 00:28:47,240 --> 00:28:50,119 Because this archipelago is in the open ocean, 232 00:28:50,120 --> 00:28:52,320 it has some of our cleanest waters. 233 00:29:04,320 --> 00:29:07,639 This is one of the reasons why Shetland 234 00:29:07,640 --> 00:29:11,000 is our main stronghold for otters. 235 00:29:18,800 --> 00:29:24,160 More than 1,000 live along its 1,600 miles of undisturbed coastline. 236 00:29:34,200 --> 00:29:38,279 Shetland's isolation and its relative lack of pollution 237 00:29:38,280 --> 00:29:40,520 suits these animals very well. 238 00:29:43,080 --> 00:29:46,639 Elsewhere, most live in or beside rivers, 239 00:29:46,640 --> 00:29:50,640 but here they spend much of their time in the sea. 240 00:29:59,520 --> 00:30:01,879 Each has its own territory 241 00:30:01,880 --> 00:30:05,560 and knows where its prey is likely to be hiding. 242 00:30:08,480 --> 00:30:13,119 But the waters in which they spend so much of their time are chilly, 243 00:30:13,120 --> 00:30:17,240 and otters need a lot of food to keep themselves warm. 244 00:30:24,680 --> 00:30:27,840 They can hold their breath for up to 90 seconds.. 245 00:30:30,040 --> 00:30:33,920 ..and reach hunting grounds as deep as ten metres. 246 00:30:45,800 --> 00:30:51,239 In summer, the waters teem with small fish, such as eelpout, 247 00:30:51,240 --> 00:30:55,880 which are easy to catch and are excellent food for the cubs. 248 00:31:07,360 --> 00:31:11,199 Little wonder that Shetland has the greatest density of otters 249 00:31:11,200 --> 00:31:13,240 anywhere in Europe. 250 00:31:21,320 --> 00:31:25,440 Otters are not the only stars in Shetland's natural history. 251 00:31:28,160 --> 00:31:32,879 Around its coast are habitats of global importance. 252 00:31:32,880 --> 00:31:35,400 Forests of kelp. 253 00:31:39,120 --> 00:31:42,359 They are among the thickest and most vigorous of their kind 254 00:31:42,360 --> 00:31:44,439 in Britain and Ireland, 255 00:31:44,440 --> 00:31:48,080 with individuals growing to over two metres tall. 256 00:31:52,200 --> 00:31:55,079 Like the seagrass, this underwater forest 257 00:31:55,080 --> 00:31:57,600 captures great quantities of carbon... 258 00:31:59,720 --> 00:32:03,200 ..and provides a home for a wide range of animals. 259 00:32:06,920 --> 00:32:09,999 One type of kelp here, the furbellow, 260 00:32:10,000 --> 00:32:12,960 has an especially feisty resident. 261 00:32:15,040 --> 00:32:20,520 Its hollow base is the favourite home of clingfish. 262 00:32:26,800 --> 00:32:29,759 This minute two-centimetre-long male 263 00:32:29,760 --> 00:32:33,800 has been left by his female to look after the eggs. 264 00:32:35,480 --> 00:32:40,520 Hundreds of them are glued to the interior of a furbellow's stem... 265 00:32:43,520 --> 00:32:45,880 ..and they're almost ready to hatch. 266 00:32:49,640 --> 00:32:52,480 It's quite a responsibility for him. 267 00:32:54,360 --> 00:32:58,999 All day long, he fans fresh, oxygen-rich sea water 268 00:32:59,000 --> 00:33:01,000 across the eggs. 269 00:33:04,720 --> 00:33:06,839 He inspects them regularly 270 00:33:06,840 --> 00:33:10,600 and quickly removes any that are infertile or dead. 271 00:33:15,240 --> 00:33:18,560 But his nursery is under attack. 272 00:33:32,760 --> 00:33:36,200 Sea urchins are devouring the furbellow. 273 00:33:41,480 --> 00:33:45,520 Their powerful jaws are destroying the clingfish's home. 274 00:33:49,920 --> 00:33:55,040 His babies are under threat, still stuck to the walls of their nursery. 275 00:33:58,880 --> 00:34:01,080 There is no escape. 276 00:34:04,560 --> 00:34:07,040 Their tiny father takes action. 277 00:34:11,160 --> 00:34:14,600 He tries to drive the urchins away by beating his tail. 278 00:34:17,920 --> 00:34:19,960 But it makes little difference. 279 00:34:21,280 --> 00:34:23,720 Time for another strategy. 280 00:34:25,480 --> 00:34:28,360 The urchins are covered in sharp spines... 281 00:34:29,720 --> 00:34:34,640 ..so the brave little father nips the urchins' sensitive tubed feet. 282 00:34:43,320 --> 00:34:49,280 Finally, the urchins give up and go in search of easier meals. 283 00:34:52,440 --> 00:34:56,360 The little male clingfish has saved his young. 284 00:35:04,880 --> 00:35:07,799 He is part of a crucial community 285 00:35:07,800 --> 00:35:12,360 that maintains the balance in this marine rainforest. 286 00:35:24,200 --> 00:35:27,679 At the height of summer, the power of the sun combines 287 00:35:27,680 --> 00:35:30,840 with the stirring action of the tides and the waves... 288 00:35:32,400 --> 00:35:34,440 ..and the ocean blooms. 289 00:35:37,000 --> 00:35:39,039 The creators of these blooms 290 00:35:39,040 --> 00:35:42,720 are myriads of floating, microscopic algae. 291 00:35:44,400 --> 00:35:48,680 They are the basis of the entire food chain in the open ocean. 292 00:35:50,120 --> 00:35:55,320 And when conditions are right, they multiply at an astonishing rate. 293 00:35:57,880 --> 00:36:01,039 Their repeated blooms are one of the main reasons 294 00:36:01,040 --> 00:36:04,840 why the seas around Britain and Ireland are so productive. 295 00:36:08,400 --> 00:36:14,479 The floating plants support a great community of tiny floating animals, 296 00:36:14,480 --> 00:36:16,600 the zooplankton. 297 00:36:18,320 --> 00:36:23,760 Tiny creatures that drift in great clouds driven by the ocean currents. 298 00:36:25,360 --> 00:36:29,679 Among them are copepods, tiny crustaceans 299 00:36:29,680 --> 00:36:33,880 that feed on the microscopic algae floating alongside them. 300 00:36:35,800 --> 00:36:38,080 The rest are mainly predators. 301 00:36:42,480 --> 00:36:44,800 Many of these are also tiny. 302 00:36:46,040 --> 00:36:49,959 The larvae of bottom-living animals like lobsters and crabs, 303 00:36:49,960 --> 00:36:53,000 some only 5mm long. 304 00:36:57,200 --> 00:36:59,239 There are also sea gooseberries, 305 00:36:59,240 --> 00:37:02,159 which propel themselves through the water 306 00:37:02,160 --> 00:37:04,920 with rows of pulsating bristles. 307 00:37:09,000 --> 00:37:13,160 They may look fragile, but they are surprisingly effective hunters. 308 00:37:18,760 --> 00:37:21,960 They extend long, thread-like tentacles. 309 00:37:26,000 --> 00:37:31,480 Other drifters that get entangled are reeled-in and eaten. 310 00:37:36,760 --> 00:37:39,439 The sea gooseberries themselves, of course, 311 00:37:39,440 --> 00:37:42,880 are also prey for larger predators... 312 00:37:44,400 --> 00:37:46,960 ..such as the melon comb jelly. 313 00:38:13,520 --> 00:38:16,840 It has a particularly large mouth. 314 00:38:24,160 --> 00:38:27,279 When it opens it, the suction it creates 315 00:38:27,280 --> 00:38:30,160 pulls its prey straight into its stomach. 316 00:38:37,840 --> 00:38:40,279 Despite the richness of our seas, 317 00:38:40,280 --> 00:38:45,080 climate change is seriously reducing the amount of zooplankton. 318 00:38:47,680 --> 00:38:51,959 And this has an effect on the entire marine food chain, 319 00:38:51,960 --> 00:38:55,160 right up to real giants. 320 00:39:00,280 --> 00:39:05,800 The largest fish in our waters is as long as a double-decker bus. 321 00:39:09,400 --> 00:39:11,320 The basking shark. 322 00:39:15,040 --> 00:39:18,479 It uses special sieve-like structures on its gills 323 00:39:18,480 --> 00:39:21,200 to filter out the zooplankton. 324 00:39:23,720 --> 00:39:26,680 And they feed on nothing else. 325 00:39:29,240 --> 00:39:35,560 In summer, these giants come close to the coast all around our isles. 326 00:39:47,640 --> 00:39:49,799 They're normally solitary, 327 00:39:49,800 --> 00:39:53,479 but when the plankton reaches the peak of its abundance, 328 00:39:53,480 --> 00:39:56,360 the sharks come together. 329 00:40:03,240 --> 00:40:05,359 They swim in formation. 330 00:40:05,360 --> 00:40:10,400 Plankton that escapes one mouth will be scooped-up by the next. 331 00:40:17,520 --> 00:40:19,959 In just a few special places 332 00:40:19,960 --> 00:40:23,439 along the western coasts of Britain and Ireland, 333 00:40:23,440 --> 00:40:28,800 basking sharks gather in large numbers to feed and breed. 334 00:40:35,200 --> 00:40:37,920 Thousands find their way here each year... 335 00:40:39,400 --> 00:40:41,960 ..a major part of the global population. 336 00:40:53,760 --> 00:40:57,360 Plankton feeders come in all sizes. 337 00:41:01,320 --> 00:41:04,879 Sand eels are only 30 centimetres long, 338 00:41:04,880 --> 00:41:08,000 but they occur in vast shoals. 339 00:41:12,960 --> 00:41:16,879 Like so many species, overfishing and warming seas 340 00:41:16,880 --> 00:41:19,480 have drastically reduced their numbers. 341 00:41:21,680 --> 00:41:26,600 They are essential prey for a wide range of top predators. 342 00:41:32,360 --> 00:41:37,360 Dolphins scour vast areas of the open ocean to track down the shoals. 343 00:41:41,480 --> 00:41:45,560 And following the dolphins comes an ocean legend... 344 00:41:47,400 --> 00:41:49,160 ..bluefin tuna. 345 00:41:52,080 --> 00:41:54,199 Weighing up to 700 kilos 346 00:41:54,200 --> 00:41:57,239 and with a top speed of more than 40mph, 347 00:41:57,240 --> 00:42:02,640 these powerful predators can make quick work of the shoal. 348 00:42:05,040 --> 00:42:09,560 Bluefins have been absent from our waters for more than 50 years. 349 00:42:13,000 --> 00:42:15,800 And they have only recently returned. 350 00:42:18,360 --> 00:42:20,279 If they are to stay, 351 00:42:20,280 --> 00:42:23,800 the overfishing of our seas will have to be stopped. 352 00:42:26,120 --> 00:42:28,040 In the sky above... 353 00:42:29,000 --> 00:42:33,360 ..gannets, looking for fish such as mackerel and herring. 354 00:42:43,080 --> 00:42:45,920 They hit the water at over 60mph. 355 00:42:51,880 --> 00:42:54,000 The impact is enormous. 356 00:42:56,520 --> 00:42:59,719 To avoid breaking their wings, they fold them back 357 00:42:59,720 --> 00:43:02,800 and turn themselves into streamlined arrows. 358 00:43:23,120 --> 00:43:27,159 65% of the world's population of northern gannets 359 00:43:27,160 --> 00:43:30,240 find their food in our seas. 360 00:43:49,080 --> 00:43:52,759 But perhaps the bird that depends most on the still-rich waters 361 00:43:52,760 --> 00:43:57,600 around Britain and Ireland is the Manx shearwater. 362 00:44:04,760 --> 00:44:07,159 Every year, our coasts are visited 363 00:44:07,160 --> 00:44:11,440 by almost the entire global population of this sea bird. 364 00:44:15,920 --> 00:44:19,479 Here in Cardigan Bay off central Wales, 365 00:44:19,480 --> 00:44:22,519 they gather in their thousands, 366 00:44:22,520 --> 00:44:26,120 attracted by the richness of our seas. 367 00:44:36,000 --> 00:44:40,719 Each summer, 350,000 pairs all return 368 00:44:40,720 --> 00:44:44,399 to this tiny island of Skomer off the Pembrokeshire coast. 369 00:44:44,400 --> 00:44:48,039 This is the largest breeding colony in the world 370 00:44:48,040 --> 00:44:51,599 and most of the island is honeycombed with their burrows. 371 00:44:51,600 --> 00:44:54,599 Tonight, under the cover of darkness, 372 00:44:54,600 --> 00:44:57,679 their chicks are starting to leave these burrows 373 00:44:57,680 --> 00:44:59,800 for the very first time. 374 00:45:02,720 --> 00:45:07,160 Watching them do so is an unforgettable privilege. 375 00:45:11,880 --> 00:45:16,079 This young bird has just emerged from its nest hole, 376 00:45:16,080 --> 00:45:18,360 maybe for the first time. 377 00:45:19,960 --> 00:45:24,080 It's about to make the most important journey of its life. 378 00:45:25,600 --> 00:45:30,080 And it needs to get every inch of altitude before it takes off. 379 00:45:31,680 --> 00:45:33,680 I can just see beyond me... 380 00:45:34,840 --> 00:45:36,800 ..there are more of them. 381 00:45:38,200 --> 00:45:40,960 One, two, three, four. 382 00:45:44,520 --> 00:45:46,880 It's just exercising its wings... 383 00:45:48,680 --> 00:45:51,720 ..in preparation for this extraordinary flight... 384 00:45:52,920 --> 00:45:57,639 ..which will take it 6,000 miles across the oceans 385 00:45:57,640 --> 00:46:01,760 to South America, to Brazil and Argentina. 386 00:46:02,880 --> 00:46:05,719 And then, after some four years, 387 00:46:05,720 --> 00:46:10,559 once again it will set out on a long oceanic journey, 388 00:46:10,560 --> 00:46:16,520 a further 6,000 miles back to this one small island of Skomer. 389 00:46:18,120 --> 00:46:19,999 Are you going to go? 390 00:46:20,000 --> 00:46:23,480 It's hesitating and who can blame it? 391 00:46:24,680 --> 00:46:29,240 An enormous journey awaits it once it takes off from here. 392 00:46:31,200 --> 00:46:35,480 This is the headquarters of this astonishing species 393 00:46:36,600 --> 00:46:39,080 ..and we are its custodians. 394 00:46:40,400 --> 00:46:42,079 Come along. 395 00:46:42,080 --> 00:46:44,240 Come along. Come along. 396 00:46:45,400 --> 00:46:47,240 Are you about to take off? 397 00:46:50,560 --> 00:46:52,200 Good luck! 398 00:46:53,640 --> 00:46:55,080 HE CHUCKLES 399 00:46:56,080 --> 00:46:58,480 What an astonishment. 400 00:47:11,360 --> 00:47:14,319 A lot has changed in my lifetime 401 00:47:14,320 --> 00:47:17,199 and today the wildlife we still have 402 00:47:17,200 --> 00:47:20,119 faces greater threats than ever before. 403 00:47:20,120 --> 00:47:23,919 Our sea birds remind us that here in Britain and Ireland 404 00:47:23,920 --> 00:47:28,279 we are very fortunate to have some of nature's greatest spectacles 405 00:47:28,280 --> 00:47:30,360 right on our doorstep. 406 00:47:31,400 --> 00:47:33,439 Because this is our home, 407 00:47:33,440 --> 00:47:37,959 it can only be our responsibility to restore and protect our wildlife. 408 00:47:37,960 --> 00:47:42,959 Perhaps you can be the first to pass these wild isles 409 00:47:42,960 --> 00:47:48,200 on to the next generation in better shape than you inherited them. 410 00:48:19,720 --> 00:48:24,679 From the Isles of Scilly in the south, to Shetland in the north, 411 00:48:24,680 --> 00:48:29,119 the ocean team spent 300 days filming the marine wildlife 412 00:48:29,120 --> 00:48:31,840 of the British Isles as never before. 413 00:48:33,240 --> 00:48:35,279 They captured new behaviours, 414 00:48:35,280 --> 00:48:38,879 experienced the worst of the Atlantic weather, 415 00:48:38,880 --> 00:48:43,360 and witnessed intimate moments in the lives of our ocean wildlife. 416 00:48:44,600 --> 00:48:49,279 Doug Anderson, is one of the world's leading underwater camera operators. 417 00:48:49,280 --> 00:48:51,599 He's worked all over the planet, 418 00:48:51,600 --> 00:48:56,520 filming some of the ocean's greatest spectacles and largest inhabitants. 419 00:48:57,840 --> 00:49:01,640 And for this series, he filmed the majority of the ocean episode. 420 00:49:03,280 --> 00:49:07,279 His passion for the underwater world began on the Isle of Arran, 421 00:49:07,280 --> 00:49:09,679 off the west coast of Scotland. 422 00:49:09,680 --> 00:49:12,759 My first underwater experience was in Lamlash Bay 423 00:49:12,760 --> 00:49:14,999 in front of my grandparents' house 424 00:49:15,000 --> 00:49:18,039 and it is burnt into my memory. 425 00:49:18,040 --> 00:49:23,039 My dad had made me a wet suit and I remember putting my face underwater 426 00:49:23,040 --> 00:49:28,879 and just being blown away but the wildness of it. 427 00:49:28,880 --> 00:49:31,839 You know, there were crabs and little fish 428 00:49:31,840 --> 00:49:33,879 and it felt like a wild place. 429 00:49:33,880 --> 00:49:35,759 I remember lifting my head up 430 00:49:35,760 --> 00:49:38,399 and looking over my shoulder back at the village - 431 00:49:38,400 --> 00:49:40,679 there was, like, the policeman doing his round, 432 00:49:40,680 --> 00:49:43,239 and people going to the shop and I was like, 433 00:49:43,240 --> 00:49:47,679 "Oh, the ocean is a wild place and behind me is what people do." 434 00:49:47,680 --> 00:49:50,000 And I never recovered. 435 00:49:53,800 --> 00:49:55,999 After learning to dive, 436 00:49:56,000 --> 00:49:58,959 Doug's passion for the underwater world 437 00:49:58,960 --> 00:50:01,799 took him on a journey far from home. 438 00:50:01,800 --> 00:50:04,879 I eventually got a job on a series called The Blue Planet, 439 00:50:04,880 --> 00:50:06,839 back in the mid-'90s. 440 00:50:06,840 --> 00:50:09,559 And then just found myself on plane out to the Azores. 441 00:50:09,560 --> 00:50:12,880 Yeah, I was, like, 27 years old, and that was the start. 442 00:50:14,160 --> 00:50:16,879 Until now, he's never had the chance to show 443 00:50:16,880 --> 00:50:19,599 what the British Isles has to offer. 444 00:50:19,600 --> 00:50:23,359 On the Wild Isles project, it just felt like an amazing opportunity 445 00:50:23,360 --> 00:50:26,639 and responsibility to take everything I've learned 446 00:50:26,640 --> 00:50:29,799 in 25 years of working all over the planet, 447 00:50:29,800 --> 00:50:33,319 and just applying all of that to here. 448 00:50:33,320 --> 00:50:36,199 Although they might be easier to reach, 449 00:50:36,200 --> 00:50:38,520 our waters have their own challenges. 450 00:50:40,440 --> 00:50:42,399 This project, in many ways, 451 00:50:42,400 --> 00:50:45,319 has been the hardest professional experience of my life. 452 00:50:45,320 --> 00:50:48,639 Everything that you do on the ocean in the North Atlantic is tough. 453 00:50:48,640 --> 00:50:51,040 We can have four seasons in a day. 454 00:50:52,160 --> 00:50:54,919 This unpredictability makes filming in our seas 455 00:50:54,920 --> 00:50:56,960 a matter of boom or bust. 456 00:50:58,560 --> 00:51:00,759 The team must be on constant standby 457 00:51:00,760 --> 00:51:03,840 to mobilise quickly when conditions are right. 458 00:51:05,720 --> 00:51:08,800 In Shetland, they're heading for the seabed. 459 00:51:11,440 --> 00:51:13,479 To record life down here, 460 00:51:13,480 --> 00:51:17,280 Doug has designed and built his own bespoke underwater tripod. 461 00:51:19,000 --> 00:51:21,840 High-powered lights illuminate the seafloor... 462 00:51:22,800 --> 00:51:25,639 ..and weights stabilise the rig, 463 00:51:25,640 --> 00:51:29,919 allowing Doug to film a time-lapse of these slow-moving creatures, 464 00:51:29,920 --> 00:51:35,160 revealing a world that few people will ever see in actuality. 465 00:51:36,600 --> 00:51:40,359 Below the kelp, Doug takes his design a step further - 466 00:51:40,360 --> 00:51:44,879 a motion-controlled slider for tracking timelapses. 467 00:51:44,880 --> 00:51:48,919 Now, he can move the camera with pinpoint accuracy, 468 00:51:48,920 --> 00:51:52,360 revealing how urchins travel through this marine forest. 469 00:51:53,720 --> 00:51:56,480 A shot that's taken months of preparation. 470 00:51:59,600 --> 00:52:02,840 But not everything in our oceans is as slow-moving. 471 00:52:03,800 --> 00:52:05,799 Off the coast of Cornwall, 472 00:52:05,800 --> 00:52:09,359 the team are chasing one of the ocean's fastest inhabitants, 473 00:52:09,360 --> 00:52:11,240 bluefin tuna. 474 00:52:12,200 --> 00:52:15,440 They have only retuned to our waters in the last few years. 475 00:52:16,680 --> 00:52:19,119 We've got all the ingredients that we need here. 476 00:52:19,120 --> 00:52:21,079 We've got dolphins, we've got tuna, 477 00:52:21,080 --> 00:52:23,439 there's gannets here, and shearwaters. 478 00:52:23,440 --> 00:52:26,519 But we need it to come together into something that we can film, 479 00:52:26,520 --> 00:52:28,239 and that's a bait ball. 480 00:52:28,240 --> 00:52:31,119 So it has to be a patch of fish jammed up against the surface 481 00:52:31,120 --> 00:52:34,000 in reasonable visibility to make it work, so... 482 00:52:35,440 --> 00:52:37,080 ..fingers crossed. 483 00:52:38,400 --> 00:52:40,399 Bait balls don't last long. 484 00:52:40,400 --> 00:52:43,719 They can be over in a matter of minutes. 485 00:52:43,720 --> 00:52:46,920 So to film tuna hunting, speed is everything. 486 00:52:48,640 --> 00:52:52,719 Radio call from one of our contacts, so we screamed down there, 487 00:52:52,720 --> 00:52:57,159 only to discover we were just a few moments too late. 488 00:52:57,160 --> 00:53:01,520 Which is really frustrating. We've got a really fast boat. 489 00:53:06,480 --> 00:53:10,879 This is so new, this set-up here, these bait fish coming here. 490 00:53:10,880 --> 00:53:13,079 It's five years, so we're just... 491 00:53:13,080 --> 00:53:16,359 Everyone's just working it out and it seems like we're not alone 492 00:53:16,360 --> 00:53:19,719 cos it's like the dolphin and the tuna are just beginning to find it 493 00:53:19,720 --> 00:53:21,760 and exploit the resource as well. 494 00:53:22,880 --> 00:53:25,999 The team use a drone to help locate the tuna 495 00:53:26,000 --> 00:53:28,680 before the bait balls disappear. 496 00:53:30,680 --> 00:53:32,959 The exciting thing is, this is England. 497 00:53:32,960 --> 00:53:35,559 We've got literally Falmouth right there 498 00:53:35,560 --> 00:53:39,359 and we've got these crazy pods of common dolphins rolling through 499 00:53:39,360 --> 00:53:42,199 and there's bluefin showing every now and then. 500 00:53:42,200 --> 00:53:44,319 It's an amazing kind of ocean scene. 501 00:53:44,320 --> 00:53:46,919 Although it looks good from the air, 502 00:53:46,920 --> 00:53:51,439 poor visibility underwater prevents Doug from getting a clear shot. 503 00:53:51,440 --> 00:53:56,119 Yeah, a total glimpse, just like the briefest of moment. 504 00:53:56,120 --> 00:53:58,199 Pretty green water, I just get in, 505 00:53:58,200 --> 00:54:01,120 and they just come through and just roll through. 506 00:54:02,720 --> 00:54:06,440 In the hope of finding clearer water, the team change location. 507 00:54:07,680 --> 00:54:09,519 We're further down the coast. 508 00:54:09,520 --> 00:54:12,079 We're going to be working further offshore, 509 00:54:12,080 --> 00:54:15,599 and we're going to be trying to join the blue water with the bluefin. 510 00:54:15,600 --> 00:54:19,239 If a big patch of pilchards on the surface or mackerel comes together, 511 00:54:19,240 --> 00:54:21,760 then come away with what we want from this. 512 00:54:23,000 --> 00:54:25,519 We have tuna, they're all over the place just now. 513 00:54:25,520 --> 00:54:28,639 We just need to wait for this sort of pot to boil, you know. 514 00:54:28,640 --> 00:54:31,039 For the bait to come together into a lump 515 00:54:31,040 --> 00:54:34,640 for long enough, for it to go static so that we can get in and film it. 516 00:54:36,360 --> 00:54:38,039 The plan works! 517 00:54:38,040 --> 00:54:41,679 The team finally get the conditions they have been seeking for so long. 518 00:54:41,680 --> 00:54:45,439 To actually see a bluefin tuna underwater in England 519 00:54:45,440 --> 00:54:48,520 is just unbelievable. 520 00:54:50,240 --> 00:54:52,719 The return of bluefin tuna to our waters 521 00:54:52,720 --> 00:54:55,679 is a sign that their population is recovering. 522 00:54:55,680 --> 00:54:59,560 But it's still a fraction of what their numbers could be. 523 00:55:02,960 --> 00:55:06,399 Since Doug left Arran over two decades ago, 524 00:55:06,400 --> 00:55:10,119 the coastal community, including his family, 525 00:55:10,120 --> 00:55:13,960 created Scotland's first marine No Take Zone. 526 00:55:16,520 --> 00:55:22,600 Since its creation in Lamlash Bay, biodiversity has increased fourfold. 527 00:55:24,240 --> 00:55:28,719 But it's one of just a handful of No Take Zones around our wild isles, 528 00:55:28,720 --> 00:55:33,039 that combined, cover less than 1% of our sea. 529 00:55:33,040 --> 00:55:35,439 The abundance of life within them 530 00:55:35,440 --> 00:55:38,559 spills out into the surrounding waters, 531 00:55:38,560 --> 00:55:42,119 enriching and strengthening the wider marine environment 532 00:55:42,120 --> 00:55:46,039 The way to get British seas back is to allow large areas 533 00:55:46,040 --> 00:55:48,639 to return to a natural state, 534 00:55:48,640 --> 00:55:53,960 and maintain those very highly protected areas for a long time. 535 00:55:54,960 --> 00:55:58,159 For Doug, celebrating the beauty of British waters 536 00:55:58,160 --> 00:56:01,400 has been a chance for him to give something back. 537 00:56:03,320 --> 00:56:06,599 If I can play a tiny part about providing the visuals 538 00:56:06,600 --> 00:56:10,079 to allow that conversation to happen in a meaningful way, 539 00:56:10,080 --> 00:56:13,119 for people on all sides of the argument 540 00:56:13,120 --> 00:56:17,359 to imagine what lies beneath those grey waves, 541 00:56:17,360 --> 00:56:20,960 then I think it would be an extraordinary thing. 542 00:56:29,920 --> 00:56:32,999 The Open University has produced a free poster 543 00:56:33,000 --> 00:56:37,959 exploring our Wild Isles and their diverse habitat and species. 544 00:56:37,960 --> 00:56:41,000 Order your copy by calling... 545 00:56:43,760 --> 00:56:45,840 ..or go to... 546 00:56:49,080 --> 00:56:50,759 ..and follow the links 547 00:56:50,760 --> 00:56:52,599 to the Open University. 548 00:56:52,600 --> 00:56:56,439 If you'd like to play your part in restoring our Wild Isles 549 00:56:56,440 --> 00:56:59,279 and learn more about what you can do to help, 550 00:56:59,280 --> 00:57:02,840 just search Wild Isles on the BBC website.