LERWICK, Scotland — Shetlanders are no strangers to being forced into — and out of — political unions. Over the past 1,300 years, this windswept, oil-rich North Sea archipelago has been invaded by Vikings, given to Scotland in lieu of a dowry for a Danish princess, and incorporated into the United Kingdom in 1707.

Now, these islands of around 25,000 people are divided over the end of another, briefer political marriage — with the European Union.

For the fishermen whose mighty boats are tied up at the dock in Lerwick, Shetland’s main town, Brexit holds the promise of unfettered access to some of Europe’s richest waters. But others here worry that the U.K.’s most northerly redoubt could struggle to attract jobs and visitors that are vital to life on these remote islands.

“As a local authority, we have great concerns about Shetland’s future after Brexit,” says Alastair Cooper, chair of the development committee of Shetland’s local council. “A lot of the infrastructure and improvements to Shetland has been [due to] European funding. We depend to some extent on EU nationals in our hospitality and seafood sectors.”

Shetland has a distinctive political and cultural identity but, like the rest of Scotland, most voters here supported remaining in the EU in last year's Brexit referendum. On a bright late summer afternoon, the European Union’s starry flag glistens on a metal plaque near the pier at Lerwick. EU funds will help to build a massive new fish market that locals hope will encourage more trawlers to land their catch in Shetland instead of sailing 200 miles south to Peterhead on the Scottish mainland.

For some the European Union remains an unwelcome intrusion imposing restriction

But the view of Brussels from Lerwick is not universally rosy. In 1973, newly oil-rich Shetland was one of only two regions in Britain to vote against joining what was then the European Economic Community. Over time attitudes changed, but for some the European Union remains an unwelcome intrusion imposing restrictions, most notably via the Common Fisheries Policy.

“The distinction between what we are allowed to catch and what is in our water is so great, we have to redress that. Over two-thirds of the fish here is taken out by non-U.K. vessels,” says Simon Collins, chief executive of Shetland Fishermen's Association. “Every autumn you have the spectacle of Faroese vessels fishing our fish after we have had to tie up.”

Millionaires' island

The seas around Shetland are home to the largest deposits of oil and gas in the EU. The arrival of "black gold" in the 1970s transformed Shetland, generating billions for the local economy through an innovative taxation scheme that levied a surcharge on every barrel of oil landed on the islands. But it is the fish that live in Shetland’s choppy waters that are the real cash crop.

Fishing and seafood make up around a third of the islands’ £1.2 billion annual economy, compared with around £100 million from oil and gas. Lerwick lands more fish than England, Wales and Northern Ireland combined. (In 2012, over a dozen Shetland fishermen were fined for their part in a massive £63 million fraud that involved circumventing EU quotas.)

Whalsay, on the eastern side of the Shetland archipelago, is often referred to as “millionaires' island,” such is the wealth generated by local fishermen. At least 20 of the island’s skippers and former vessel owners are said to have amassed seven-figure fortunes from the sea. Local fishermen hope that figure will rise further after Brexit: 81 percent of voters on Whalsay and in nearby South Unst supported leaving the EU, one of the highest pro-Brexit votes in the U.K.

“For our guys, Brexit is a no-brainer,” says Collins, a dual British-French national who worked as a translator in France before coming to Shetland to take over as head of the islands’ largest fishing lobby group. It was the Englishman’s first job in the fishing industry.

“The fishermen felt they needed someone with that experience in Europe,” he says at the association's headquarters in an office block with a Nordic-style slanted roof on Lerwick’s esplanade.

On the wall behind Collins’ desk hangs a political map of the U.K. Thirty or so pins and thumbnail photos denote “fishing-friendly” MPs. The majority are Tories. A couple are from Northern Ireland's Democratic Unionist Party and Labour. And there’s the local MP, Alastair Carmichael of the Liberal Democrats.

“Politically we have a strong set of cards,” says Collins. But he admits that access to Scottish fishing waters could be traded away during the Brexit negotiations. U.K. Environment Secretary — and ardent Brexiteer — Michael Gove told Danish fishermen last month that EU boats could still fish in British waters after Brexit.

“There are bigger things than the fishing industry,” acknowledges Collins. “But politically all our ducks are in a row.”

Shetland processes fish too, with much of the produce exported. Boxy fish-processing plants dominate the industrial estates on the outskirts of Lerwick. While the cooperatives that own and work the fishing trawlers are largely from Shetland, around half of the fish processing workforce comes from other EU countries, according to statistics from Shetland Council.

“We have 167 employees. Thirty-five of those come from the EU,” says Grant Cumming, managing director of Grieg Seafood, one of the world’s largest fish farming operations. The company recently opened a £15 million salmon hatchery in Girlsta, a few kilometers north of Lerwick. In all, the value of the fish processing and aquaculture industries are almost three times that of catching fish.

Cumming is worried about the effect that any tightening on immigration after Brexit could have on the flow of skilled workers. “We need very highly qualified, experienced aquaculture guys. This is a new technology for the U.K. so we have to recruit from the EU,” says Cumming. “Without access to EU workers, we would struggle to do everything we do.”

Help wanted

Access to workers is an important issue across Shetland. The islands enjoy almost full employment. Each morning, local radio announces numerous job vacancies. While many young people leave Shetland (in part due to the high cost of living caused by the oil boom), attracting new people can be a challenge, especially in the health care sector, among other professions.

A submission by Shetland Council to a recent inquiry into the impact of immigration by the Scottish parliament's Culture, Tourism, Europe and External Relations Committee concluded that any decrease in immigrant numbers “would have a negative economic impact disproportionate to the number of workers in question.”

The Scottish National Party (SNP) government in Edinburgh has called for Scotland to have a separate immigration system post Brexit, which would give Scotland more flexibility in attracting workers. But the U.K. government has so far shown no support for the idea.

“Everyone is employed. There are businesses struggling to grow because they can’t find workers. The fear now is that this could get worse as people mightn’t be able to come,” says Maree Todd, an SNP member of the Scottish parliament for the Highlands and Islands.

Immigration has been a facet of Shetland life for centuries but, since the 1970s, Shetland has become increasingly cosmopolitan too. The nearest train station might be in the Norwegian city of Bergen, but Lerwick boasts a state-of-the-art cultural center. The roads are excellent and almost every village has its own heated swimming pool thanks to the oil levy. Most summer days, cruise ships disgorge international tourists into the shops selling woolens in the town’s winding streets.

The islands — and many islanders — have particularly close links to Scandinavia. The Shetland flag — the colors of the Scottish saltire in the form of a Nordic cross — that flies from many homes and public buildings reflects the complexity of identities here. Lerwick’s street names celebrate King Harald and St Olaf.

"We are Norway’s backdoor into Europe, but that’s not the same as saying we are Norwegian” -- Local broadcaster Mary Blance

Politically, Shetland has often done its own thing, too. At Westminster, Shetland has been a liberal bastion for more than 50 years. All but one of the local councilors is an independent.

Brexit could yet reopen thorny questions about Shetland’s own political future. The islands have grappled for decades with the question of how they should be governed. Ahead of the 2014 referendum on Scottish independence, Tavish Scott, the local member of the Scottish parliament, floated the idea of Shetland remaining part of the U.K. even if Scotland voted to break away.

Back in the 1970s, the "Shetland Movement" called for greater autonomy for the islands. In 1974, Shetland council gained control of its own seabed and oil income.

In 1997, almost two-thirds of Shetland voters backed the establishment of the Scottish parliament. But some Shetlanders would like to see government brought closer to home. They look enviously to the Faroe Islands, with its independent parliament and sovereign waters. A pro-autonomy campaign group founded in 2015 has the backing of three local councilors and claims the support of many more local people.

“The Scottish government in Edinburgh is very remote from issues here. More self-determination would allow us to tailor our laws to be more reflective of our society,” says James Titcomb, chairman of Wir Shetland (“Our Shetland” in the local dialect). The group is broadly pro-Brexit and Titcomb says it envisages a future for Shetland comparable to “a British Overseas territory. Like the Channel Islands or the Isle of Man, or the Falklands.”

Shetland is “more Norse than it is Scottish,” says Titcomb, who was born in Hong Kong to English parents who served in the British army. The idea of Shetland as more Nordic than Scottish is often expounded in newspaper articles about the islands’ putative secession, but it is far from one universally held by islanders themselves.

“Shetland has always been at a crossroads. We are Norway’s backdoor into Europe, but that’s not the same as saying we are Norwegian,” says local broadcaster Mary Blance.