1 00:00:34,043 --> 00:00:39,883 Here in Britain and Ireland, we have some of the richest seas in Europe. 2 00:00:41,003 --> 00:00:45,563 Our varied coastline, if you include all the many offshore islands, 3 00:00:45,563 --> 00:00:48,203 is over 22,000 miles long, 4 00:00:48,203 --> 00:00:52,203 and none of us live more than 70 miles away from the sea. 5 00:00:53,163 --> 00:00:56,723 Yet few of us have seen the wonders beyond the beach 6 00:00:56,723 --> 00:00:58,723 and beneath the waves. 7 00:00:58,723 --> 00:01:01,083 In this episode, we will take you 8 00:01:01,083 --> 00:01:03,563 from the most southerly point of the 9 00:01:03,563 --> 00:01:06,243 United Kingdom to the furthest north, 10 00:01:06,243 --> 00:01:09,763 to explain why our seas can be so productive 11 00:01:09,763 --> 00:01:13,123 and reveal the threats that they face today. 12 00:01:28,523 --> 00:01:33,323 Every winter, a warm ocean current, the gulf stream, 13 00:01:33,323 --> 00:01:37,003 drives huge storms across the Atlantic... 14 00:01:39,163 --> 00:01:44,323 ...away from the Caribbean and straight towards our shores. 15 00:01:48,963 --> 00:01:54,083 There, every winter, they batter the west coasts of our islands. 16 00:02:03,363 --> 00:02:06,883 Waves with energy built up across an entire ocean 17 00:02:06,883 --> 00:02:09,323 are hurled at our coasts. 18 00:02:13,683 --> 00:02:16,603 Walls of water more than ten metres tall 19 00:02:16,603 --> 00:02:19,243 crash repeatedly onto the rocks. 20 00:02:32,323 --> 00:02:35,083 And as the water at depth is churned, 21 00:02:35,083 --> 00:02:38,523 it brings nutrients up towards the surface. 22 00:02:44,283 --> 00:02:48,643 These nutrients, combined with the warmth of the gulf stream, 23 00:02:48,643 --> 00:02:52,803 are the reason why marine life here proliferates 24 00:02:52,803 --> 00:02:56,123 with such extraordinary richness and variety. 25 00:03:23,243 --> 00:03:25,283 Each year, in autumn, 26 00:03:25,283 --> 00:03:29,523 evidence of this marine abundance appears on land. 27 00:03:34,523 --> 00:03:39,803 13,000 grey seals haul out on Blakeney Point in Norfolk. 28 00:03:41,243 --> 00:03:44,403 It's the largest seal colony in England. 29 00:03:46,883 --> 00:03:50,723 Females, having spent most of the year feeding in our rich waters, 30 00:03:50,723 --> 00:03:53,243 are preparing to produce their young. 31 00:03:54,843 --> 00:03:57,643 Newly born, the pups are helpless... 32 00:04:00,283 --> 00:04:04,363 ...and for their first few weeks, entirely dependent on their mothers. 33 00:04:06,043 --> 00:04:09,083 Seal milk is more than 50% fat... 34 00:04:10,043 --> 00:04:13,003 ...and the pups put on two kilos a day. 35 00:04:16,723 --> 00:04:20,483 At first, parent and pup are inseparable. 36 00:04:24,603 --> 00:04:29,523 But then, after a few days, the youngsters start to explore. 37 00:04:31,843 --> 00:04:34,803 Other females don't tolerate the appearance 38 00:04:34,803 --> 00:04:37,523 of unrelated pups on their patch. 39 00:04:57,043 --> 00:05:00,083 Posing an even greater threat than the females... 40 00:05:01,043 --> 00:05:02,883 ...are the males. 41 00:05:10,363 --> 00:05:13,763 Three metres long and weighing 350 kilos... 42 00:05:15,563 --> 00:05:18,123 ...they have come here to mate. 43 00:05:21,963 --> 00:05:25,243 They know that soon after the pups are born, 44 00:05:25,243 --> 00:05:29,443 the females will become sexually receptive once again. 45 00:05:33,403 --> 00:05:36,643 This big male tries to control all the females 46 00:05:36,643 --> 00:05:38,883 on this stretch of the beach. 47 00:05:42,443 --> 00:05:44,963 But he has a rival. 48 00:05:54,363 --> 00:05:57,763 The big male warns off the challenger, 49 00:05:57,763 --> 00:06:00,243 but the intruder takes no notice. 50 00:06:06,883 --> 00:06:09,203 There's only one way to settle this. 51 00:06:11,203 --> 00:06:12,843 Violence. 52 00:06:24,323 --> 00:06:26,243 When the males fight, 53 00:06:26,243 --> 00:06:29,123 they take no notice of any pup that gets in their way. 54 00:06:33,803 --> 00:06:35,803 The pup's mother intervenes... 55 00:06:40,323 --> 00:06:43,043 ...allowing her pup to wriggle away. 56 00:06:49,723 --> 00:06:52,963 Finally, the battle turns. 57 00:06:57,123 --> 00:07:00,723 The intruder starts to retreat towards the sea. 58 00:07:04,243 --> 00:07:07,323 Now, the smaller males join the chase. 59 00:07:20,403 --> 00:07:24,363 The big male has retained his right to mate. 60 00:07:29,403 --> 00:07:33,443 Despite these battles, Blakeney Point still provides the pups 61 00:07:33,443 --> 00:07:35,643 with an excellent start in life. 62 00:07:37,283 --> 00:07:39,883 5,000 are born here each year. 63 00:07:43,883 --> 00:07:47,923 A remarkable 40% of the world population of grey seals 64 00:07:47,923 --> 00:07:50,363 lives around the British Isles. 65 00:07:52,083 --> 00:07:55,523 Impressive evidence of the richness of our seas. 66 00:08:00,723 --> 00:08:04,683 Beneath the surface, that wealth is very evident. 67 00:08:15,443 --> 00:08:18,843 Cold, nutrient-rich currents from the north 68 00:08:18,843 --> 00:08:22,323 mingle with the warm waters of the gulf stream, 69 00:08:22,323 --> 00:08:26,603 and support an astonishing variety of plants and animals. 70 00:08:31,403 --> 00:08:34,763 There are more than 10,000 different species here. 71 00:09:09,563 --> 00:09:13,763 The effect of the gulf stream is felt most keenly 72 00:09:13,763 --> 00:09:17,963 at our southernmost point, around the Isles of Scilly. 73 00:09:21,283 --> 00:09:24,683 Here grows one of the biggest stretches of seagrass 74 00:09:24,683 --> 00:09:28,323 to be found anywhere in British and Irish waters. 75 00:09:31,043 --> 00:09:35,443 Seagrass is important globally because it collects carbon 76 00:09:35,443 --> 00:09:39,603 up to 35 times faster than a tropical rainforest. 77 00:09:42,603 --> 00:09:46,283 But we have lost nearly 90% of our seagrass, 78 00:09:46,283 --> 00:09:50,443 mainly because of pollution and disturbance of the seabed. 79 00:09:53,843 --> 00:09:56,763 Nonetheless, these marine meadows 80 00:09:56,763 --> 00:10:00,323 are home to a wide variety of small animals. 81 00:10:01,763 --> 00:10:06,283 Including this perhaps somewhat surprising one. 82 00:10:11,163 --> 00:10:13,803 A spiny seahorse. 83 00:10:14,843 --> 00:10:18,363 One of just two species of seahorse that live in our waters. 84 00:10:24,163 --> 00:10:27,843 They thrive in the warmth brought by the gulf stream. 85 00:10:35,523 --> 00:10:37,563 The seagrass provides them 86 00:10:37,563 --> 00:10:40,723 with the seclusion they prefer for their courtship. 87 00:10:53,963 --> 00:10:57,523 A crucial part of their underwater dance 88 00:10:57,523 --> 00:11:01,643 involves a gentle entwining of their tails. 89 00:11:05,363 --> 00:11:09,043 It's behaviour you might think to be more typical 90 00:11:09,043 --> 00:11:12,523 of the warm, balmy waters of the Mediterranean. 91 00:11:22,003 --> 00:11:24,243 And there is another creature 92 00:11:24,243 --> 00:11:27,523 that is also more usually found in warmer waters. 93 00:11:32,243 --> 00:11:34,283 The common cuttlefish. 94 00:11:37,683 --> 00:11:41,883 It's the most northerly of all cuttlefish species. 95 00:11:44,203 --> 00:11:48,123 This pregnant female, about the size of a rugby football, 96 00:11:48,123 --> 00:11:52,803 is being guarded by a male as she prepares to lay her eggs. 97 00:11:55,323 --> 00:11:58,283 First, she cleans her chosen site 98 00:11:58,283 --> 00:12:01,923 by squirting jets of water over the seaweed. 99 00:12:05,243 --> 00:12:08,083 Several dozen black eggs are already here, 100 00:12:08,083 --> 00:12:10,563 having been laid the previous day. 101 00:12:21,643 --> 00:12:23,723 And now she adds more... 102 00:12:24,683 --> 00:12:29,483 ...one by one, until there are up to 3,000 or so. 103 00:12:38,963 --> 00:12:40,883 A month later... 104 00:12:43,723 --> 00:12:48,163 ...during the night, the eggs start to hatch. 105 00:12:54,483 --> 00:12:59,883 A perfectly formed baby cuttlefish, no larger than a pea. 106 00:13:06,723 --> 00:13:08,923 Within a few weeks, 107 00:13:08,923 --> 00:13:12,443 a male has grown to a length of around six centimetres 108 00:13:12,443 --> 00:13:15,443 and is already a stealthy hunter. 109 00:13:26,203 --> 00:13:31,043 His eyesight is so sensitive that he's able to hunt by moonlight. 110 00:13:53,763 --> 00:13:56,043 But when the moon disappears... 111 00:13:58,163 --> 00:14:00,643 ...even he cannot see 112 00:14:00,643 --> 00:14:05,083 and the darkness usually brings hunting to an end. 113 00:14:09,843 --> 00:14:12,323 But on just a few nights each year... 114 00:14:13,283 --> 00:14:15,803 ...something extraordinary happens. 115 00:14:19,763 --> 00:14:26,203 Tiny light-producing algae create vast clouds of bioluminescence. 116 00:14:30,843 --> 00:14:35,923 They're stimulated to switch on by any sudden movement in the water. 117 00:14:42,443 --> 00:14:46,243 Even the slight swirl produced by a tiny crab as it breathes 118 00:14:46,243 --> 00:14:48,163 has an effect. 119 00:14:52,163 --> 00:14:54,883 The hunter must move very smoothly, 120 00:14:54,883 --> 00:14:58,043 to avoid creating a light show of his own. 121 00:15:26,243 --> 00:15:30,283 The light of the algae has enabled it to see its prey 122 00:15:30,283 --> 00:15:32,803 and so hunt throughout the night. 123 00:15:40,523 --> 00:15:44,403 A year later, the cuttlefish are fully grown 124 00:15:44,403 --> 00:15:47,923 and this male is now looking for a female. 125 00:15:51,323 --> 00:15:55,323 But the traditional breeding site is empty. 126 00:16:03,283 --> 00:16:05,883 The cuttlefish that gathered here to mate... 127 00:16:07,283 --> 00:16:09,963 ...have been caught in a fishing pot. 128 00:16:14,483 --> 00:16:18,083 They may be among the most intelligent animals in the sea... 129 00:16:19,803 --> 00:16:23,203 ...but they've been fooled by a simple trap. 130 00:16:26,603 --> 00:16:29,603 And once in it, there is no escape. 131 00:16:46,843 --> 00:16:51,363 The male outside spots a possible mate. 132 00:16:59,803 --> 00:17:01,963 But he can't reach her. 133 00:17:15,323 --> 00:17:20,163 Our cuttlefish population can tolerate some loss to fishing, 134 00:17:20,163 --> 00:17:25,323 but surely we shouldn't put pots where they habitually breed, 135 00:17:25,323 --> 00:17:29,003 and prevent them from producing their next generation 136 00:17:45,683 --> 00:17:51,803 Away from the coast, the seabed may seem barren and lifeless. 137 00:17:53,683 --> 00:17:56,483 But looks can be deceptive. 138 00:17:59,043 --> 00:18:03,883 This muddy seafloor is rich in bacteria and algae 139 00:18:03,883 --> 00:18:08,483 and provides food for one animal in particular. 140 00:18:10,203 --> 00:18:14,923 A slow-moving creature that can grow up to a length of six centimetres. 141 00:18:17,803 --> 00:18:21,083 The royal flush sea slug. 142 00:18:25,363 --> 00:18:28,563 Thousands graze the seafloor here. 143 00:18:33,163 --> 00:18:36,323 But with so much competition for the same food, 144 00:18:36,323 --> 00:18:38,563 supplies eventually run out. 145 00:18:40,323 --> 00:18:42,923 And the sea slugs have to move on... 146 00:18:43,923 --> 00:18:46,243 ...in their own strange way. 147 00:18:50,163 --> 00:18:55,323 They flap their wing-like mantles and rise up from the seabed. 148 00:19:01,683 --> 00:19:06,563 Drifting on the slow current, they can travel for miles. 149 00:19:26,443 --> 00:19:31,723 This extraordinary mass migration has never been filmed before. 150 00:19:47,203 --> 00:19:51,403 Eventually, they reach new feeding grounds. 151 00:20:04,523 --> 00:20:09,323 And now they can start hoovering the seabed once more. 152 00:20:19,163 --> 00:20:22,003 As spring turns to summer, 153 00:20:22,003 --> 00:20:27,363 another very different migration begins all along the south coast, 154 00:20:27,363 --> 00:20:29,843 and for a very different reason. 155 00:20:33,803 --> 00:20:36,483 A young female spider crab. 156 00:20:39,523 --> 00:20:44,683 She is searching these sandy plains for others of her own kind. 157 00:20:54,723 --> 00:20:57,483 Spider crabs are normally solitary, 158 00:20:57,483 --> 00:21:02,363 but now, in the summer, they start to assemble into groups. 159 00:21:05,843 --> 00:21:10,723 And then, when there are enough of them, they start to travel. 160 00:21:20,123 --> 00:21:23,763 Together, they journey for miles across the seabed, 161 00:21:23,763 --> 00:21:27,043 all heading in the same direction. 162 00:21:40,083 --> 00:21:42,123 Groups join together 163 00:21:42,123 --> 00:21:47,203 and the travellers become one great horde, several-thousand strong. 164 00:21:51,883 --> 00:21:55,923 They are about to face the most dangerous time of their lives. 165 00:22:01,243 --> 00:22:06,803 They have outgrown their hard shells and must now escape from them. 166 00:22:11,603 --> 00:22:13,923 A new shell is expandable, 167 00:22:13,923 --> 00:22:17,363 but it remains soft for several hours 168 00:22:17,363 --> 00:22:21,203 and until it hardens, its owner has no defence. 169 00:22:27,323 --> 00:22:30,763 That is why they've made this journey together. 170 00:22:34,723 --> 00:22:37,683 There is safety in numbers. 171 00:22:46,643 --> 00:22:50,643 Ocean currents are one reason why our waters are so rich. 172 00:22:50,643 --> 00:22:54,883 Another is the exceptional size of our tides. 173 00:22:56,363 --> 00:22:58,443 Vast amounts of water 174 00:22:58,443 --> 00:23:01,443 are continuously transported around our islands 175 00:23:01,443 --> 00:23:03,603 by these powerful currents. 176 00:23:06,843 --> 00:23:10,363 The third biggest tidal rise and fall on the planet 177 00:23:10,363 --> 00:23:13,643 occurs in the estuary of the River Severn. 178 00:23:17,963 --> 00:23:19,843 From low tide, 179 00:23:19,843 --> 00:23:23,963 the sea level rises by as much as the height of a five-storey building 180 00:23:23,963 --> 00:23:27,723 and then falls again, twice every day. 181 00:23:31,883 --> 00:23:36,043 These huge transformations churn-up the nutrients 182 00:23:36,043 --> 00:23:38,843 and replenish the mudflats. 183 00:23:48,683 --> 00:23:51,883 Further north, on the west coast of Scotland, 184 00:23:51,883 --> 00:23:56,243 the power of our tides creates another great spectacle. 185 00:24:00,603 --> 00:24:03,043 The Corryvreckan whirlpool. 186 00:24:03,043 --> 00:24:05,483 25 metres across. 187 00:24:12,443 --> 00:24:15,523 It's the third largest whirlpool in the world. 188 00:24:21,963 --> 00:24:25,603 These powerful tidal currents mix-up the water, 189 00:24:25,603 --> 00:24:30,363 constantly bringing nutrients from the depths up to the surface layers. 190 00:24:35,883 --> 00:24:40,883 And the influence of the tides can extend right down to the seafloor. 191 00:24:45,283 --> 00:24:49,363 The animals down here thrive in these ever-moving currents. 192 00:24:49,363 --> 00:24:53,083 Every square inch is bursting with life. 193 00:25:00,043 --> 00:25:04,163 The flowing water brings a never-ending supply of food. 194 00:25:05,443 --> 00:25:10,083 Brittle stars and sea cucumbers compete to collect all they can. 195 00:25:20,603 --> 00:25:24,283 So many creatures inevitably attracts predators. 196 00:25:33,483 --> 00:25:37,403 {\an8}The seven-armed starfish - half a metre across. 197 00:25:39,763 --> 00:25:43,163 {\an8}The brittle stars do their best to get out of their way. 198 00:25:49,563 --> 00:25:52,883 The huge starfish feel for their prey 199 00:25:52,883 --> 00:25:55,843 using hundreds of sensitive tubed feet 200 00:25:55,843 --> 00:25:58,763 that line the underside of their arms. 201 00:26:01,243 --> 00:26:05,603 Yet, not every animal they encounter tries to escape. 202 00:26:08,683 --> 00:26:11,643 This hermit crab, with its powerful claws, 203 00:26:11,643 --> 00:26:14,203 is well able to defend itself. 204 00:26:24,523 --> 00:26:29,523 Finally, the persistent starfish find what they're looking for. 205 00:26:35,443 --> 00:26:37,563 A queen scallop. 206 00:26:41,323 --> 00:26:46,563 Its lines of simple black eyes are able to detect fast-moving threats. 207 00:26:49,083 --> 00:26:52,123 But the starfish moves quite slowly... 208 00:26:54,643 --> 00:26:57,323 ...and the scallop doesn't notice. 209 00:27:00,043 --> 00:27:03,363 Only when the scallop feels the predator's probing feet, 210 00:27:03,363 --> 00:27:05,283 does it react. 211 00:27:11,163 --> 00:27:15,403 It swims away by clapping together the two parts of its shell. 212 00:27:21,483 --> 00:27:24,523 It's a surprisingly effective technique, 213 00:27:24,523 --> 00:27:27,883 and with luck will carry the scallop to safety. 214 00:27:32,523 --> 00:27:36,203 But scallops don't have a strong sense of direction... 215 00:27:39,443 --> 00:27:42,803 ...and the starfish just keep coming. 216 00:27:46,403 --> 00:27:50,403 The starfish first pulls the scallop shell apart 217 00:27:50,403 --> 00:27:53,643 and then inserts its extendable stomach 218 00:27:53,643 --> 00:27:56,083 to digest the scallop's flesh. 219 00:27:58,763 --> 00:28:01,883 The smell of the feast drifts through the water 220 00:28:01,883 --> 00:28:03,923 and attracts scavengers. 221 00:28:07,163 --> 00:28:08,683 Whelks. 222 00:28:10,603 --> 00:28:13,043 They are the clean-up crew. 223 00:28:18,403 --> 00:28:23,403 Tidal beds like these can easily be destroyed by bottom-trawling. 224 00:28:25,283 --> 00:28:28,043 Protecting those that survive is essential 225 00:28:28,043 --> 00:28:31,123 if we are to preserve the richness of our seas. 226 00:28:37,923 --> 00:28:42,083 100 miles from mainland Scotland lies Shetland, 227 00:28:42,083 --> 00:28:44,963 the most northerly part of the British Isles. 228 00:28:47,283 --> 00:28:50,163 Because this archipelago is in the open ocean, 229 00:28:50,163 --> 00:28:52,363 it has some of our cleanest waters. 230 00:29:04,363 --> 00:29:07,683 This is one of the reasons why Shetland 231 00:29:07,683 --> 00:29:11,043 is our main stronghold for otters. 232 00:29:18,843 --> 00:29:24,203 More than 1,000 live along its 1,600 miles of undisturbed coastline. 233 00:29:34,243 --> 00:29:38,323 Shetland's isolation and its relative lack of pollution 234 00:29:38,323 --> 00:29:40,563 suits these animals very well. 235 00:29:43,123 --> 00:29:46,683 Elsewhere, most live in or beside rivers, 236 00:29:46,683 --> 00:29:50,683 but here they spend much of their time in the sea. 237 00:29:59,563 --> 00:30:01,923 Each has its own territory 238 00:30:01,923 --> 00:30:05,603 and knows where its prey is likely to be hiding. 239 00:30:08,523 --> 00:30:13,163 But the waters in which they spend so much of their time are chilly, 240 00:30:13,163 --> 00:30:17,283 and otters need a lot of food to keep themselves warm. 241 00:30:24,723 --> 00:30:27,883 They can hold their breath for up to 90 seconds... 242 00:30:30,083 --> 00:30:33,963 ...and reach hunting grounds as deep as ten metres. 243 00:30:45,843 --> 00:30:51,283 In summer, the waters teem with small fish, such as eelpout, 244 00:30:51,283 --> 00:30:55,923 which are easy to catch and are excellent food for the cubs. 245 00:31:07,403 --> 00:31:11,243 Little wonder that Shetland has the greatest density of otters 246 00:31:11,243 --> 00:31:13,283 anywhere in Europe. 247 00:31:21,363 --> 00:31:25,483 Otters are not the only stars in Shetland's natural history. 248 00:31:28,203 --> 00:31:32,923 Around its coast are habitats of global importance. 249 00:31:32,923 --> 00:31:35,443 Forests of kelp. 250 00:31:39,163 --> 00:31:42,403 They are among the thickest and most vigorous of their kind 251 00:31:42,403 --> 00:31:44,483 in Britain and Ireland, 252 00:31:44,483 --> 00:31:48,123 with individuals growing to over two metres tall. 253 00:31:52,243 --> 00:31:55,123 Like the seagrass, this underwater forest 254 00:31:55,123 --> 00:31:57,643 captures great quantities of carbon... 255 00:31:59,763 --> 00:32:03,243 ...and provides a home for a wide range of animals. 256 00:32:06,963 --> 00:32:10,043 One type of kelp here, the furbellow, 257 00:32:10,043 --> 00:32:13,003 has an especially feisty resident. 258 00:32:15,083 --> 00:32:20,563 Its hollow base is the favourite home of clingfish. 259 00:32:26,843 --> 00:32:29,803 This minute two-centimetre-long male 260 00:32:29,803 --> 00:32:33,843 has been left by his female to look after the eggs. 261 00:32:35,523 --> 00:32:40,563 Hundreds of them are glued to the interior of a furbellow's stem... 262 00:32:43,563 --> 00:32:45,923 ...and they're almost ready to hatch. 263 00:32:49,683 --> 00:32:52,523 It's quite a responsibility for him. 264 00:32:54,403 --> 00:32:59,043 All day long, he fans fresh, oxygen-rich sea water 265 00:32:59,043 --> 00:33:01,043 across the eggs. 266 00:33:04,763 --> 00:33:06,883 {\an8}He inspects them regularly 267 00:33:06,883 --> 00:33:10,643 {\an8}and quickly removes any that are infertile or dead. 268 00:33:15,283 --> 00:33:18,603 But his nursery is under attack. 269 00:33:32,803 --> 00:33:36,243 Sea urchins are devouring the furbellow. 270 00:33:41,523 --> 00:33:45,563 Their powerful jaws are destroying the clingfish's home. 271 00:33:49,963 --> 00:33:55,083 His babies are under threat, still stuck to the walls of their nursery. 272 00:33:58,923 --> 00:34:01,123 There is no escape. 273 00:34:04,603 --> 00:34:07,083 Their tiny father takes action. 274 00:34:11,203 --> 00:34:14,643 He tries to drive the urchins away by beating his tail. 275 00:34:17,963 --> 00:34:20,003 But it makes little difference. 276 00:34:21,323 --> 00:34:23,763 Time for another strategy. 277 00:34:25,523 --> 00:34:28,403 The urchins are covered in sharp spines... 278 00:34:29,763 --> 00:34:34,683 ...so the brave little father nips the urchins' sensitive tubed feet. 279 00:34:43,363 --> 00:34:49,323 Finally, the urchins give up and go in search of easier meals. 280 00:34:52,483 --> 00:34:56,403 The little male clingfish has saved his young. 281 00:35:04,923 --> 00:35:07,843 He is part of a crucial community 282 00:35:07,843 --> 00:35:12,403 that maintains the balance in this marine rainforest. 283 00:35:24,243 --> 00:35:27,723 At the height of summer, the power of the sun combines 284 00:35:27,723 --> 00:35:30,883 with the stirring action of the tides and the waves... 285 00:35:32,443 --> 00:35:34,483 ...and the ocean blooms. 286 00:35:37,043 --> 00:35:39,083 The creators of these blooms 287 00:35:39,083 --> 00:35:42,763 are myriads of floating, microscopic algae. 288 00:35:44,443 --> 00:35:48,723 They are the basis of the entire food chain in the open ocean. 289 00:35:50,163 --> 00:35:55,363 And when conditions are right, they multiply at an astonishing rate. 290 00:35:57,923 --> 00:36:01,083 Their repeated blooms are one of the main reasons 291 00:36:01,083 --> 00:36:04,883 why the seas around Britain and Ireland are so productive. 292 00:36:08,443 --> 00:36:14,523 The floating plants support a great community of tiny floating animals, 293 00:36:14,523 --> 00:36:16,643 the zooplankton. 294 00:36:18,363 --> 00:36:23,803 Tiny creatures that drift in great clouds driven by the ocean currents. 295 00:36:25,403 --> 00:36:29,723 Among them are copepods, tiny crustaceans 296 00:36:29,723 --> 00:36:33,923 that feed on the microscopic algae floating alongside them. 297 00:36:35,843 --> 00:36:38,123 The rest are mainly predators. 298 00:36:42,523 --> 00:36:44,843 Many of these are also tiny. 299 00:36:46,083 --> 00:36:50,003 The larvae of bottom-living animals like lobsters and crabs, 300 00:36:50,003 --> 00:36:53,043 some only 5mm long. 301 00:36:57,243 --> 00:36:59,283 There are also sea gooseberries, 302 00:36:59,283 --> 00:37:02,203 which propel themselves through the water 303 00:37:02,203 --> 00:37:04,963 with rows of pulsating bristles. 304 00:37:09,043 --> 00:37:13,203 They may look fragile, but they are surprisingly effective hunters. 305 00:37:18,803 --> 00:37:22,003 They extend long, thread-like tentacles. 306 00:37:26,043 --> 00:37:31,523 Other drifters that get entangled are reeled-in and eaten. 307 00:37:36,803 --> 00:37:39,483 The sea gooseberries themselves, of course, 308 00:37:39,483 --> 00:37:42,923 are also prey for larger predators... 309 00:37:44,443 --> 00:37:47,003 ...such as the melon comb jelly. 310 00:38:13,563 --> 00:38:16,883 It has a particularly large mouth. 311 00:38:24,203 --> 00:38:27,323 When it opens it, the suction it creates 312 00:38:27,323 --> 00:38:30,203 pulls its prey straight into its stomach. 313 00:38:37,883 --> 00:38:40,323 Despite the richness of our seas, 314 00:38:40,323 --> 00:38:45,123 climate change is seriously reducing the amount of zooplankton. 315 00:38:47,723 --> 00:38:52,003 And this has an effect on the entire marine food chain, 316 00:38:52,003 --> 00:38:55,203 right up to real giants. 317 00:39:00,323 --> 00:39:05,843 The largest fish in our waters is as long as a double-decker bus. 318 00:39:09,443 --> 00:39:11,363 The basking shark. 319 00:39:15,083 --> 00:39:18,523 It uses special sieve-like structures on its gills 320 00:39:18,523 --> 00:39:21,243 to filter out the zooplankton. 321 00:39:23,763 --> 00:39:26,723 And they feed on nothing else. 322 00:39:29,283 --> 00:39:35,603 In summer, these giants come close to the coast all around our isles. 323 00:39:47,683 --> 00:39:49,843 They're normally solitary, 324 00:39:49,843 --> 00:39:53,523 but when the plankton reaches the peak of its abundance, 325 00:39:53,523 --> 00:39:56,403 the sharks come together. 326 00:40:03,283 --> 00:40:05,403 They swim in formation. 327 00:40:05,403 --> 00:40:10,443 Plankton that escapes one mouth will be scooped-up by the next. 328 00:40:17,563 --> 00:40:20,003 In just a few special places 329 00:40:20,003 --> 00:40:23,483 along the western coasts of Britain and Ireland, 330 00:40:23,483 --> 00:40:28,843 basking sharks gather in large numbers to feed and breed. 331 00:40:35,243 --> 00:40:37,963 Thousands find their way here each year... 332 00:40:39,443 --> 00:40:42,003 ...a major part of the global population. 333 00:40:53,803 --> 00:40:57,403 Plankton feeders come in all sizes. 334 00:41:01,363 --> 00:41:04,923 Sand eels are only 30 centimetres long, 335 00:41:04,923 --> 00:41:08,043 but they occur in vast shoals. 336 00:41:13,003 --> 00:41:16,923 Like so many species, overfishing and warming seas 337 00:41:16,923 --> 00:41:19,523 have drastically reduced their numbers. 338 00:41:21,723 --> 00:41:26,643 They are essential prey for a wide range of top predators. 339 00:41:32,403 --> 00:41:37,403 Dolphins scour vast areas of the open ocean to track down the shoals. 340 00:41:41,523 --> 00:41:45,603 And following the dolphins comes an ocean legend... 341 00:41:47,443 --> 00:41:49,203 ...bluefin tuna. 342 00:41:52,123 --> 00:41:54,243 Weighing up to 700 kilos 343 00:41:54,243 --> 00:41:57,283 and with a top speed of more than 40mph, 344 00:41:57,283 --> 00:42:02,683 these powerful predators can make quick work of the shoal. 345 00:42:05,083 --> 00:42:09,603 Bluefins have been absent from our waters for more than 50 years. 346 00:42:13,043 --> 00:42:15,843 And they have only recently returned. 347 00:42:18,403 --> 00:42:20,323 If they are to stay, 348 00:42:20,323 --> 00:42:23,843 the overfishing of our seas will have to be stopped. 349 00:42:26,163 --> 00:42:28,083 In the sky above... 350 00:42:29,043 --> 00:42:33,403 ...gannets, looking for fish such as mackerel and herring. 351 00:42:43,123 --> 00:42:45,963 They hit the water at over 60mph. 352 00:42:51,923 --> 00:42:54,043 The impact is enormous. 353 00:42:56,563 --> 00:42:59,763 To avoid breaking their wings, they fold them back 354 00:42:59,763 --> 00:43:02,843 and turn themselves into streamlined arrows. 355 00:43:23,163 --> 00:43:27,203 65% of the world's population of northern gannets 356 00:43:27,203 --> 00:43:30,283 find their food in our seas. 357 00:43:49,123 --> 00:43:52,803 But perhaps the bird that depends most on the still-rich waters 358 00:43:52,803 --> 00:43:57,643 around Britain and Ireland is the Manx shearwater. 359 00:44:04,803 --> 00:44:07,203 Every year, our coasts are visited 360 00:44:07,203 --> 00:44:11,483 by almost the entire global population of this sea bird. 361 00:44:15,963 --> 00:44:19,523 Here in Cardigan Bay off central Wales, 362 00:44:19,523 --> 00:44:22,563 they gather in their thousands, 363 00:44:22,563 --> 00:44:26,163 attracted by the richness of our seas. 364 00:44:36,043 --> 00:44:40,763 Each summer, 350,000 pairs all return 365 00:44:40,763 --> 00:44:44,443 to this tiny island of Skomer off the Pembrokeshire coast. 366 00:44:44,443 --> 00:44:48,083 This is the largest breeding colony in the world 367 00:44:48,083 --> 00:44:51,643 and most of the island is honeycombed with their burrows. 368 00:44:51,643 --> 00:44:54,643 Tonight, under the cover of darkness, 369 00:44:54,643 --> 00:44:57,723 their chicks are starting to leave these burrows 370 00:44:57,723 --> 00:44:59,843 for the very first time. 371 00:45:02,763 --> 00:45:07,203 Watching them do so is an unforgettable privilege. 372 00:45:11,923 --> 00:45:16,123 This young bird has just emerged from its nest hole, 373 00:45:16,123 --> 00:45:18,403 maybe for the first time. 374 00:45:20,003 --> 00:45:24,123 It's about to make the most important journey of its life. 375 00:45:25,643 --> 00:45:30,123 And it needs to get every inch of altitude before it takes off. 376 00:45:31,723 --> 00:45:33,723 I can just see beyond me... 377 00:45:34,883 --> 00:45:36,843 ...there are more of them. 378 00:45:38,243 --> 00:45:41,003 One, two, three, four. 379 00:45:44,563 --> 00:45:46,923 It's just exercising its wings... 380 00:45:48,723 --> 00:45:51,763 ...in preparation for this extraordinary flight... 381 00:45:52,963 --> 00:45:57,683 ...which will take it 6,000 miles across the oceans 382 00:45:57,683 --> 00:46:01,803 to South America, to Brazil and Argentina. 383 00:46:02,923 --> 00:46:05,763 And then, after some four years, 384 00:46:05,763 --> 00:46:10,603 once again it will set out on a long oceanic journey, 385 00:46:10,603 --> 00:46:16,563 a further 6,000 miles back to this one small island of Skomer. 386 00:46:18,163 --> 00:46:20,043 Are you going to go? 387 00:46:20,043 --> 00:46:23,523 It's hesitating and who can blame it? 388 00:46:24,723 --> 00:46:29,283 An enormous journey awaits it once it takes off from here. 389 00:46:31,243 --> 00:46:35,523 This is the headquarters of this astonishing species 390 00:46:36,643 --> 00:46:39,123 ...and we are its custodians. 391 00:46:40,443 --> 00:46:44,283 Come along. Come along. 392 00:46:45,443 --> 00:46:47,283 Are you about to take off? 393 00:46:50,603 --> 00:46:52,243 Good luck! 394 00:46:56,123 --> 00:46:58,523 What an astonishment. 395 00:47:11,403 --> 00:47:14,363 A lot has changed in my lifetime 396 00:47:14,363 --> 00:47:17,243 and today the wildlife we still have 397 00:47:17,243 --> 00:47:20,163 faces greater threats than ever before. 398 00:47:20,163 --> 00:47:23,963 Our sea birds remind us that here in Britain and Ireland 399 00:47:23,963 --> 00:47:28,323 we are very fortunate to have some of nature's greatest spectacles 400 00:47:28,323 --> 00:47:30,403 right on our doorstep. 401 00:47:31,443 --> 00:47:33,483 Because this is our home, 402 00:47:33,483 --> 00:47:38,003 it can only be our responsibility to restore and protect our wildlife. 403 00:47:38,003 --> 00:47:43,003 Perhaps you can be the first to pass these wild isles 404 00:47:43,003 --> 00:47:48,243 on to the next generation in better shape than you inherited them. 405 00:48:19,763 --> 00:48:24,723 From the Isles of Scilly in the south, to Shetland in the north, 406 00:48:24,723 --> 00:48:29,163 the ocean team spent 300 days filming the marine wildlife 407 00:48:29,163 --> 00:48:31,883 of the British Isles as never before. 408 00:48:33,283 --> 00:48:35,323 They captured new behaviours, 409 00:48:35,323 --> 00:48:38,923 experienced the worst of the Atlantic weather, 410 00:48:38,923 --> 00:48:43,403 and witnessed intimate moments in the lives of our ocean wildlife. 411 00:48:44,643 --> 00:48:49,323 Doug Anderson, is one of the world's leading underwater camera operators. 412 00:48:49,323 --> 00:48:51,643 He's worked all over the planet, 413 00:48:51,643 --> 00:48:56,563 filming some of the ocean's greatest spectacles and largest inhabitants. 414 00:48:57,883 --> 00:49:01,683 And for this series, he filmed the majority of the ocean episode. 415 00:49:03,323 --> 00:49:07,323 His passion for the underwater world began on the Isle of Arran, 416 00:49:07,323 --> 00:49:09,723 off the west coast of Scotland. 417 00:49:09,723 --> 00:49:12,803 {\an8}My first underwater experience was in Lamlash Bay 418 00:49:12,803 --> 00:49:15,043 {\an8}in front of my grandparents' house 419 00:49:15,043 --> 00:49:18,083 and it is burnt into my memory. 420 00:49:18,083 --> 00:49:23,083 My dad had made me a wet suit and I remember putting my face underwater 421 00:49:23,083 --> 00:49:28,923 and just being blown away but the wildness of it. 422 00:49:28,923 --> 00:49:31,883 You know, there were crabs and little fish 423 00:49:31,883 --> 00:49:33,923 and it felt like a wild place. 424 00:49:33,923 --> 00:49:35,803 I remember lifting my head up 425 00:49:35,803 --> 00:49:38,443 and looking over my shoulder back at the village - 426 00:49:38,443 --> 00:49:40,723 there was, like, the policeman doing his round, 427 00:49:40,723 --> 00:49:43,283 and people going to the shop and I was like, 428 00:49:43,283 --> 00:49:47,723 "Oh, the ocean is a wild place and behind me is what people do." 429 00:49:47,723 --> 00:49:50,043 And I never recovered. 430 00:49:53,843 --> 00:49:56,043 After learning to dive, 431 00:49:56,043 --> 00:49:59,003 Doug's passion for the underwater world 432 00:49:59,003 --> 00:50:01,843 took him on a journey far from home. 433 00:50:01,843 --> 00:50:04,923 I eventually got a job on a series called The Blue Planet, 434 00:50:04,923 --> 00:50:06,883 back in the mid-'90s. 435 00:50:06,883 --> 00:50:09,603 And then just found myself on plane out to the Azores. 436 00:50:09,603 --> 00:50:12,923 Yeah, I was, like, 27 years old, and that was the start. 437 00:50:14,203 --> 00:50:16,923 Until now, he's never had the chance to show 438 00:50:16,923 --> 00:50:19,643 what the British Isles has to offer. 439 00:50:19,643 --> 00:50:23,403 On the Wild Isles project, it just felt like an amazing opportunity 440 00:50:23,403 --> 00:50:26,683 and responsibility to take everything I've learned 441 00:50:26,683 --> 00:50:29,843 in 25 years of working all over the planet, 442 00:50:29,843 --> 00:50:33,363 and just applying all of that to here. 443 00:50:33,363 --> 00:50:36,243 Although they might be easier to reach, 444 00:50:36,243 --> 00:50:38,563 our waters have their own challenges. 445 00:50:40,483 --> 00:50:42,443 This project, in many ways, 446 00:50:42,443 --> 00:50:45,363 has been the hardest professional experience of my life. 447 00:50:45,363 --> 00:50:48,683 Everything that you do on the ocean in the North Atlantic is tough. 448 00:50:48,683 --> 00:50:51,083 We can have four seasons in a day. 449 00:50:52,203 --> 00:50:54,963 This unpredictability makes filming in our seas 450 00:50:54,963 --> 00:50:57,003 a matter of boom or bust. 451 00:50:58,603 --> 00:51:00,803 The team must be on constant standby 452 00:51:00,803 --> 00:51:03,883 to mobilise quickly when conditions are right. 453 00:51:05,763 --> 00:51:08,843 In Shetland, they're heading for the seabed. 454 00:51:11,483 --> 00:51:13,523 To record life down here, 455 00:51:13,523 --> 00:51:17,323 Doug has designed and built his own bespoke underwater tripod. 456 00:51:19,043 --> 00:51:21,883 High-powered lights illuminate the seafloor... 457 00:51:22,843 --> 00:51:25,683 ...and weights stabilise the rig, 458 00:51:25,683 --> 00:51:29,963 {\an8}allowing Doug to film a time-lapse of these slow-moving creatures, 459 00:51:29,963 --> 00:51:35,203 {\an8}revealing a world that few people will ever see in actuality. 460 00:51:36,643 --> 00:51:40,403 Below the kelp, Doug takes his design a step further - 461 00:51:40,403 --> 00:51:44,923 a motion-controlled slider for tracking timelapses. 462 00:51:44,923 --> 00:51:48,963 Now, he can move the camera with pinpoint accuracy, 463 00:51:48,963 --> 00:51:52,403 revealing how urchins travel through this marine forest. 464 00:51:53,763 --> 00:51:56,523 A shot that's taken months of preparation. 465 00:51:59,643 --> 00:52:02,883 But not everything in our oceans is as slow-moving. 466 00:52:03,843 --> 00:52:05,843 Off the coast of Cornwall, 467 00:52:05,843 --> 00:52:09,403 the team are chasing one of the ocean's fastest inhabitants, 468 00:52:09,403 --> 00:52:11,283 bluefin tuna. 469 00:52:12,243 --> 00:52:15,483 They have only retuned to our waters in the last few years. 470 00:52:16,723 --> 00:52:19,163 We've got all the ingredients that we need here. 471 00:52:19,163 --> 00:52:21,123 We've got dolphins, we've got tuna, 472 00:52:21,123 --> 00:52:23,483 there's gannets here, and shearwaters. 473 00:52:23,483 --> 00:52:26,563 But we need it to come together into something that we can film, 474 00:52:26,563 --> 00:52:28,283 and that's a bait ball. 475 00:52:28,283 --> 00:52:31,163 So it has to be a patch of fish jammed up against the surface 476 00:52:31,163 --> 00:52:34,043 in reasonable visibility to make it work, so... 477 00:52:35,483 --> 00:52:37,123 ...fingers crossed. 478 00:52:38,443 --> 00:52:40,443 Bait balls don't last long. 479 00:52:40,443 --> 00:52:43,763 They can be over in a matter of minutes. 480 00:52:43,763 --> 00:52:46,963 So to film tuna hunting, speed is everything. 481 00:52:48,683 --> 00:52:52,763 Radio call from one of our contacts, so we screamed down there, 482 00:52:52,763 --> 00:52:57,203 only to discover we were just a few moments too late. 483 00:52:57,203 --> 00:53:01,563 Which is really frustrating. We've got a really fast boat. 484 00:53:06,523 --> 00:53:10,923 This is so new, this set-up here, these bait fish coming here. 485 00:53:10,923 --> 00:53:13,123 It's five years, so we're just... 486 00:53:13,123 --> 00:53:16,403 Everyone's just working it out and it seems like we're not alone 487 00:53:16,403 --> 00:53:19,763 cos it's like the dolphin and the tuna are just beginning to find it 488 00:53:19,763 --> 00:53:21,803 and exploit the resource as well. 489 00:53:22,923 --> 00:53:26,043 The team use a drone to help locate the tuna 490 00:53:26,043 --> 00:53:28,723 before the bait balls disappear. 491 00:53:30,723 --> 00:53:33,003 The exciting thing is, this is England. 492 00:53:33,003 --> 00:53:35,603 We've got literally Falmouth right there 493 00:53:35,603 --> 00:53:39,403 and we've got these crazy pods of common dolphins rolling through 494 00:53:39,403 --> 00:53:42,243 and there's bluefin showing every now and then. 495 00:53:42,243 --> 00:53:44,363 It's an amazing kind of ocean scene. 496 00:53:44,363 --> 00:53:46,963 Although it looks good from the air, 497 00:53:46,963 --> 00:53:51,483 poor visibility underwater prevents Doug from getting a clear shot. 498 00:53:51,483 --> 00:53:56,163 Yeah, a total glimpse, just like the briefest of moment. 499 00:53:56,163 --> 00:53:58,243 Pretty green water, I just get in, 500 00:53:58,243 --> 00:54:01,163 and they just come through and just roll through. 501 00:54:02,763 --> 00:54:06,483 In the hope of finding clearer water, the team change location. 502 00:54:07,723 --> 00:54:09,563 We're further down the coast. 503 00:54:09,563 --> 00:54:12,123 We're going to be working further offshore, 504 00:54:12,123 --> 00:54:15,643 and we're going to be trying to join the blue water with the bluefin. 505 00:54:15,643 --> 00:54:19,283 If a big patch of pilchards on the surface or mackerel comes together, 506 00:54:19,283 --> 00:54:21,803 then come away with what we want from this. 507 00:54:23,043 --> 00:54:25,563 We have tuna, they're all over the place just now. 508 00:54:25,563 --> 00:54:28,683 We just need to wait for this sort of pot to boil, you know. 509 00:54:28,683 --> 00:54:31,083 For the bait to come together into a lump 510 00:54:31,083 --> 00:54:34,683 for long enough, for it to go static so that we can get in and film it. 511 00:54:36,403 --> 00:54:38,083 The plan works! 512 00:54:38,083 --> 00:54:41,723 The team finally get the conditions they have been seeking for so long. 513 00:54:41,723 --> 00:54:45,483 To actually see a bluefin tuna underwater in England 514 00:54:45,483 --> 00:54:48,563 is just unbelievable. 515 00:54:50,283 --> 00:54:52,763 The return of bluefin tuna to our waters 516 00:54:52,763 --> 00:54:55,723 is a sign that their population is recovering. 517 00:54:55,723 --> 00:54:59,603 But it's still a fraction of what their numbers could be. 518 00:55:03,003 --> 00:55:06,443 Since Doug left Arran over two decades ago, 519 00:55:06,443 --> 00:55:10,163 the coastal community, including his family, 520 00:55:10,163 --> 00:55:14,003 created Scotland's first marine No Take Zone. 521 00:55:16,563 --> 00:55:22,643 Since its creation in Lamlash Bay, biodiversity has increased fourfold. 522 00:55:24,283 --> 00:55:28,763 But it's one of just a handful of No Take Zones around our wild isles, 523 00:55:28,763 --> 00:55:33,083 that combined, cover less than 1% of our sea. 524 00:55:33,083 --> 00:55:35,483 The abundance of life within them 525 00:55:35,483 --> 00:55:38,603 spills out into the surrounding waters, 526 00:55:38,603 --> 00:55:42,163 enriching and strengthening the wider marine environment 527 00:55:42,163 --> 00:55:46,083 The way to get British seas back is to allow large areas 528 00:55:46,083 --> 00:55:48,683 to return to a natural state, 529 00:55:48,683 --> 00:55:54,003 and maintain those very highly protected areas for a long time. 530 00:55:55,003 --> 00:55:58,203 For Doug, celebrating the beauty of British waters 531 00:55:58,203 --> 00:56:01,443 has been a chance for him to give something back. 532 00:56:03,363 --> 00:56:06,643 If I can play a tiny part about providing the visuals 533 00:56:06,643 --> 00:56:10,123 to allow that conversation to happen in a meaningful way, 534 00:56:10,123 --> 00:56:13,163 for people on all sides of the argument 535 00:56:13,163 --> 00:56:17,403 to imagine what lies beneath those grey waves, 536 00:56:17,403 --> 00:56:21,003 then I think it would be an extraordinary thing. 537 00:56:29,963 --> 00:56:33,043 The Open University has produced a free poster 538 00:56:33,043 --> 00:56:38,003 exploring our Wild Isles and their diverse habitat and species. 539 00:56:38,003 --> 00:56:41,043 Order your copy by calling... 540 00:56:43,803 --> 00:56:45,883 ...or go to... 541 00:56:49,123 --> 00:56:50,803 ...and follow the links 542 00:56:50,803 --> 00:56:52,643 to the Open University. 543 00:56:52,643 --> 00:56:56,483 If you'd like to play your part in restoring our Wild Isles 544 00:56:56,483 --> 00:56:59,323 and learn more about what you can do to help, 545 00:56:59,323 --> 00:57:02,883 just search Wild Isles on the BBC website.