Denmark on Monday completed a controversial fence along the border with Germany to protect its giant pork industry from wild boar that could carry African swine fever.

Around 5,000 pig farms export 28 million pigs annually, accounting for half of Danish agricultural exports and 5% of all exports, according to the Danish Agriculture and Food Council.

Read more:Germany: Schnitzel shortage predicted over swine fever in China 

Why is the fence controversial?

The 1.5-meter tall and half-meter deep fence cost €11 million ($12 million). It runs along the entirety of the Danish-German border, from the Wadden Sea in the west to the Flensburg Fjord in the east.

Critics say it is a waste of money that won't work against a problem that doesn't exist, while environmentalists have raised concerns about its impact on the ecosystem. The fence is also symbolic for the Danish right-wing keen on hard borders and keeping migrants out.

How will it affect the environment?

Environmental groups are concerned that construction of the fence will disturb the migration of wild animals and birds, some of which are protected by Danish and EU legislation.

"We know from experiences around the world that physical barriers such as a fence impact animal migration," Thor Hjarsen, senior biologists at World Wildlife Foundation in Denmark, told DW last year after the Environment Ministry signed off on the fence construction.

Deer, wolves, otters, foxes, golden jackals and cranes are among the species that could be impacted.

Will the fence work?

Denmark is part of the EU's border-free Schengen Zone. Roads and railroads crossing the border won't be impacted by the fence. That leaves dozens of openings in the border through which wild boar could pass.

"The problem with the fence is that there is no documentation that it works," Hans Kristensen, a hunter, wildlife author and expert on wild boar migration who lives along the border, told DW last year. "On the other hand, there is plenty of evidence it won't work."

Wild boar are distributed along the eastern coast of the Danish-German border and are very rare in the west, Kristensen said. In the east, the wild boar can swim across the Flensburg Fjord, a body of water separating Germany and Denmark.

"A fence can't be erected there. That is part of the border where they cross," he said.

Symbolic for the far-right

Critics like Kristensen and Hjarsen say the biggest risk of swine fever spreading isn't from wild boar crossing the border. Instead, the threat is from trucks transporting infected swine or spreading contaminated food.

Rather than tackling the virus, the fence may have a symbolic effect to show the powerful pig farming industry that the pro-agriculture government is doing something and to appease the right-wing in Denmark.

Politicians from the right-wing populist Danish People's Party, for example, have in the past suggested erecting a tall, barbed-wire fence with motion detectors along the German border as Europe witnessed an influx of migrants in recent years.

"You won't see anyone admit it, but one reason why the fence could get votes in parliament was because of the right-wing in Denmark," Kristensen said. "The fence won't keep wild boar out and it won't keep migrants out, but the symbolic value is immense for the right wing."

How big a threat is swine fever?

The virus is fatal to pigs but does not kill humans. Scientists have warned that a quarter of the world's pigs could die from the virus as it spreads through much of Asia.

In Europe, it has been found in several countries including Estonia, Latvia, Lithuania and Poland. A swine fever outbreak in Denmark would halt all non-EU pork exports.

No swine fever has been detected in Germany, raising questions as to why the fence is even being built.

Read more: African swine fever: What you need to know

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