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The mystery of northeast Scotland’s catastrophic harbour seal decline

  • Written by  Laura Cole
  • Published in Wildlife
The mystery of northeast Scotland’s catastrophic harbour seal decline
29 Nov
2018
Laura Cole travels to Orkney to find out why numbers of harbour seals have fallen by 78 per cent since 2000

Any luck, Mònica?’ asks the bartender in the Sands Hotel pub, pouring a drink for the ecologist just taking her seat. Outside the window, a storm is rolling in. It shakes a pyramid of lobster cages and rankles the sea. But the pub is warm, even noisy, for a weekday evening. Over the hubbub, Dr Mònica Arso says: ‘Pupping season has just started, so we’re starting to see some newborns at the haul out sites.’ She knows she hasn’t answered the intended question, that of Orkney’s most pressing mystery – what is causing the major decline of its harbour seals? ‘It’s still early days,’ she adds and takes her drink, examining the weather outside. She will need to go over the storm forecast before her 5am start searching for seals.

Orkney is a group of islands ten miles off the northeast coast of Scotland. The archipelago’s impressive profile is clearly on display from the viewpoint at John o’Groats on the mainland. Low-lying green humps on its east side and the sheer cliffs of Hoy in the west. The vista seems to lure travellers over from the northeasternmost tip of the Scottish mainland. ‘How could I resist going a bit further?’ the curious travellers may say on the ferry crossing the Pentland Firth. Orcadians have a name for such visitors – ‘ferry loupers’. Once off, you find that the largest island, Mainland, serves as a gateway to yet more islands such as Westray, Eday, Sanday, Shapinsay, and further again, to Shetland. They seem to have a way of drawing visitors ever onwards, into the North Sea.

20180617Orkney BQ2 8578A rarer sight: harbour seal numbers have nosedived by 78 per cent since 2000

It’s this location in the North Sea that also makes the archipelago so alluring to wildlife. The powerful strait running under its southern side is a vital passage for porpoises, dolphins, orca and minke whales. Its cliffs are living walls of fulmars, great skuas, auks and other sea-birds. Then there are the seals. Orkney is an internationally significant breeding ground for grey and harbour seals, and every day thousands hunt and haul out around its shores. Seal remains have been found among the islands’ 5,000-year-old neolithic sites, suggesting that humans have shared the beaches for millennia. It’s even thought that Orkney gets its name from the Old Norse Orkneyjar – or ‘seal islands’.

In the past 20 years however, something major has changed. Harbour seal numbers have nosedived by 78 per cent since 2000, prompting alarm from marine biologists. Similar trends appeared in the Shetland islands with declines of 30 per cent, and the Tay estuary at 95 per cent. Bizarrely, populations in the west of Scotland seemed to have remained stable. Harbour seals in Orkney began to appear with unusual wounds – clean-cut spirals or ‘corkscrews’ around their bodies. ‘Initially we thought it was propeller blades,’ says Ross Flett, who runs Orkney’s seal rescue centre. Experts have been investigating if the two findings were linked. More fundamentally, they are searching for the causes for decline, and whether it is set to continue.

20180617Orkney BQ2 7983Long-term studies watching marine populations are Dr Arso’s ‘thing’

LOCAL KNOWLEDGE

It’s this question that brought Dr Arso to Orkney in 2015. She is an ecologist at the Sea Mammal Research Unit (SMRU) at the University of Saint Andrews, 160 miles south of the islands. It was the unit’s helicopter surveys that first revealed the magnitude of the decline and that Orkney had the most to lose. Its harbour seal population had dropped from 8,500, one of the largest in the UK, to just 1,800.

What the SMRU needed was long-term monitoring from the ground, a study that could compare crippled populations in the east of Scotland with the strong populations in the west. Arso was up for the job. While some might baulk at the idea of spending whole summers alone on windy cliffs, long-term studies watching marine populations are ‘her thing’. Like a biologist-Poirot, armed with a long-range scope and a clipboard, she scouted potential locations to observe Orkney’s seals during the pupping season. She came to South Ronaldsay island and found Widewall Bay, which had good access to a small population of around 100 seals. To get a true sense of how many used to be here, however, she needed to talk to an Orcadian.

‘There were around 500 at one point,’ says George Rouse. A farmer for almost all of his 75 years, he used to farm an uninhabited island called Hunda by crossing a causeway. ‘When I took the tractor across it, the seals would follow me along the water, back and forth, back and forth,’ he says.

‘There were so many, we considered setting up hides for tourists and making a business out of it,’ says his son, Magnus Rouse, a drystone waller. ‘But then [the seal numbers] began to drop.’

20180617Orkney BQ2 8545Orkney's current harbour seal population is around 1,800, down from 8,500

When Arso arrived, the Rouses helped her find one of her cliff locations to monitor the seals. ‘They know the area better, and I needed to get as close to the seals as possible,’ she says. Seals are curious. They’ll swim close enough to scrutinise you with big blinking eyes, then they’ll follow, even blow bubbles. ‘But only when they are in water,’ says Arso. ‘When they haul out to rest, they feel more vulnerable and won’t let us close.’

Since meeting Arso, the Rouses often speak to other islanders about the decline. ‘It’d be hard to find anyone living near the water who isn’t worried about it,’ says George. Sometimes they speculate about the causes. ‘Maybe there isn’t enough food for them anymore,’ offers Magnus.

It’s possible. In fact, lack of food is one of three suspect causes. ‘But first we need to see where the decline is happening,’ says Arso, ‘and the key to that is females.’ It’s why, every day of pupping season for the last three years, she has counted and identified females and whether or not they have offspring with them. ‘If they don’t produce pups that will tell us something, if the females themselves decline that will tell us something else,’ she explains.

GREY MENACE

‘Mine was curled up on the grass, it was just so beautiful, this wee thing,’ says Nyree Harper, a community nurse in her early forties and keen seal watcher.

‘Mine half frightened me to death. I walked down to the cliff and –whah! – there it was, 15 feet up the slope,’ says Heather Parry, a 60-something swimming fanatic.

The my-seal-your-seal conversation is a common one for Harper and Parry. Both live on the water’s edge of Widewall Bay and see the pupping season first-hand. Both are also ‘newcomers’, the Orcadian name for people who were lured on a permanent basis to Orkney. Both stayed for the waterside life: Harper for foraging Widewall Bay’s saltwater plants, Parry for swimming in its icy water.

20180617Orkney BQ1 9831Nyree Harper, an Orkney island resident, examines the coast

Even in the short time they have been here, they have noticed fewer harbour seals. ‘At first I wondered if they were moving,’ says Parry. ‘If there are more in the west, maybe they could just be going that way.’ But that was before something unusual washed up on her beach. It looked like a 1980s mobile phone and had a Saint Andrews label. It was a tracking tag.

When she returned the tag to the university she discovered it had been attached to a Widewall female seal for a year. ‘What came back was a bunch of scribbles,’ she says, describing the map the seal had created. ‘It showed that the female seal had spent all her time going back and forth just within Widewall Bay.’

Arso had been the scientist at the other end of the email. ‘We got solid data from 2016,’ she says. ‘We tagged ten seals and it helped reaffirm what we suspected, which is that they are pretty consistent to place.’ In other words, they haven’t just moved. ‘Whatever is affecting them is affecting them here.’

In talking, Harper and Parry bring up another suspect. ‘There are still lots of grey seals around. Some people still worry when you hear them singing.’

The grey seals share many of the haul-out sites with harbour seals. Larger in size and greater in number than the harbour seals around Orkney, their mournful song has made them the subject of local folklore for centuries. Many of the stories of shapeshifting seal people – or selkies – originate from the archipelago. ‘Some people still won’t let their dogs go near them, because they are worried seals will tempt them into the water,’ says Harper.

In reality, grey seals don’t present much of a threat to people or dogs. A harbour seal, however, might have more to fear. In 2014, a grey seal discovery shocked scientists. On the Isle of May, a biologist watched a male grey seal snatch a grey seal pup and drag it to freshwater pool. Holding the pup underwater, the male killed the pup, ate some of the blubber and left the same spiral injuries found on the harbour seals. ‘The perpetrator was finally caught in the act,’ says Arso.‘The male was seen killing and eating four pups within the next few days.’ The resulting research paper was nicknamed the ‘Hannibal Report’ and researchers now knew that grey seals were capable of inflicting the mysterious ‘corkscrew’ marks on their prey. The question is are they doing it to harbour seals as well? The larger animals have now become the foremost suspects for the decline of the harbour seals. 

GreysealGrey seals like these may be one of the culprits of the harbour seal's decline

‘The master’s students I teach love that story,’ Arso adds with a tone of warning. She feels it’s important that we don’t become blinded and assume that this is the only factor at play. ‘Outside of the killings, it’s also vital to look at how greys might be competing with the harbour seals within the environment – for a decreased food supply, for example,’ she says.

RESCUE MISSION

Seals are protected in Orkney, but that has not always been the case. During the 1960s and 1970s, thousands of grey and harbour seals were culled both due to a perceived threat to the fishing industry as well as for sealskins. The culls were met with huge protests which put Orkney at the centre of an international debate.

That’s when Ross Flett moved here. With a platinum ponytail and walrus moustache, Flett cuts an imposing figure, further emphasised by a bassy Glaswegian voice. Originally a hydroelectric engineer, he came to work on Orkney’s diesel power station and got caught up in anti-cull campaigns on Westray island, where a cull of 2,000 pups was planned.

‘We knew that some of the culling was for handbags to sell to tourists,’ he says, ‘so we went out to the islands and starting spraying the pups with pink dye.’ The protesters achieved their goals. The last major cull for fishing was called off in 1978 and a European ban on seal skin ended the market. 

Today, the Scottish government still allots licences to shoot seals that cause trouble for industrial fishing and they remain controversial. ‘However their numbers are not high enough to be responsible for the magnitude of the declines,’ says Arso. ‘Shooting is no longer considered a primary cause.’

20180617Orkney BQ1 9714Ross Flett now runs the island's seal rescue centre

Flett never went back to hydroelectric work. The diesel power station was made redundant by the arrival of subsea cables. ‘Which was just as well,’ he says as he had fallen into a new kind of work. In 1977, an Orkney environmental group found a sick harbour seal pup off the coast of Mainland and as the only member with a house near the water, Flett took it in. ‘I had no idea what to do with it. Didn’t have a clue,’ he says. Suzy, as he came to call her, lived in his bathroom for weeks. When she got bigger, he could take her to the rock pools 100 yards down a steep track from his house. ‘Eventually she didn’t want to come out of them, so I’d have to go in there and bring her back myself,’ he says.

When Suzy was old enough, he released her back into Orkney waters. Since then, he has founded the islands’ seal rescue centre, and has rereleased hundreds of grey seals, harbour seals and even the odd otter into the wild.

In 40 years of working with seals, Flett has seen viruses take out high numbers, but there were always animals with symptoms to explain what was happening. ‘This time, they just seem to be disappearing, I have never seen anything like it,’ he says. ‘Maybe it’s something in the water?’

TOXIC WATERS

Flett’s guess is key to the final suspect – harmful algae blooms. ‘Blooms can create substances that are toxic, which accumulate up the food chain,’ says Arso. Such blooms occur naturally but they can be influenced by human activity near the coast. Scientists also predict that climate change might be increasing their frequency and intensity. According to 2015 study by the SMRU, toxin levels were found to be significantly higher at sites of seal decline. In more recent years, the SMRU has taken samples of Orkney seals and confirmed low levels of toxins, however ‘there’s evidence of low levels of these toxins in all UK seals,’ says Arso. ‘It could be that chronic exposure is taking its toll.’ More samples are needed and seal corpses are sent to marine labs to detect the presence of the toxins.

Food, grey seals and toxins. ‘That’s where we’re at right now,’ says Arso. ‘In fact, our studies are pointing to it being a combination of all three causes.’ She has one pupping season left in Orkney and is hopeful about the results. ‘If there is no decline – great news,’ she says. ‘If there is a decline, then at least we will have captured it on the data. We will be in a much stronger position to pinpoint the losses and do what we can to reduce them.’ It’s important work because the fate of a small population in Widewall Bay could have implications for seals all over Scotland’s coasts.

This was published in the December 2018 edition of Geographical magazine

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