Carlingford Lough is divided.

Omeath, on the southern shore of Carlingford Lough and, in the distance, Northern Ireland at sunset. | January 31, 2017 | (REUTERS/Clodagh Kilcoyne)

This picturesque estuary forms the easternmost part of the Irish border: Carlingford's north shore belongs to the British-run Northern Ireland and the south shore belongs to the Republic of Ireland, a member of the European Union. It's an unusual border situation that has long called into question the ownership of the lake's contents — and fishing and recreational ventures therein. But that dispute was settled nearly 20 years.

In 1998, after Northern Ireland's decades-long sectarian violence came to an end with the Good Friday Agreement, a cross-border body — the Loughs Agency — was created to manage the border waterways, which includes Carlingford Lough and Lough Foyle (located on the opposite side of the border). The agency's oversight of the inlets' economic, commercial, and recreational development, among other things, has largely worked for the two sides.

Then Brexit happened.

A man walks the shores of Omeath, Ireland, on the southern shore of Carlingford Lough. The left bank is Northern Ireland. | January 31, 2017. | (REUTERS/Clodagh Kilcoyne)

Skipper Shay Fitzpatrick dredges mussels from Carlingford Lough in Warrenpoint, Northern Ireland. | February 9, 2017 | (REUTERS/Clodagh Kilcoyne)

In the wake of the U.K.'s vote to leave the European Union, Northern Ireland laid claim to the loughs and its fishing rights, which Ireland immediately rejected. The two sides of the Irish loughs may soon be under the management of two different fishing agencies, as London will likely pull out of the EU Common Fisheries Policy as well. As the U.K. begins the two-year process of withdrawing from the European Union, fishermen in the area worry the reignited dispute over ownership could threaten their livelihood.

"Because we are not a big voice in the grand scheme of things nobody wants to talk to us," Brian MacDonald, a mussel fisherman and native of harbor town Warrenpoint, Northern Ireland, told Reuters. "It's two fiddlers playing two completely different tunes and we're stuck in the middle.”

Check out the scenic — but disputed — Irish loughs.

A ship dredges mussels from Carlingford Lough. | February 9, 2017 | (REUTERS/Clodagh Kilcoyne)

A worker tends to oysters on William Lynch's oyster farm on Lough Foyle — the lake on the other end of the Irish border — in Culmore, Northern Ireland. | February 10, 2017 | (REUTERS/Clodagh Kilcoyne)

A man is handed a towel after swimming in Carlingford Lough in Omeath, Ireland. | February 17, 2017 | (REUTERS/Clodagh Kilcoyne)

Sunset on the shores of Greenore, Ireland. | February 15, 2017 | (REUTERS/Clodagh Kilcoyne)

Women walk along the southern shores of Carlingford Lough; Northern Ireland is in the background. | February 15, 2017 | (REUTERS/Clodagh Kilcoyne)

A poster in Greencastle, Ireland, refers to a proposed new car ferry that would run from Northern Ireland to Ireland through Carlingford Lough. | February 8, 2017 | (REUTERS/Clodagh Kilcoyne)

An oysters cleaning facility in Moville, Ireland. | February 10, 2017 | (REUTERS/Clodagh Kilcoyne)

The banks of Carlingford Lough in Greencastle, Northern Ireland. | February 8, 2017 | (REUTERS/Clodagh Kilcoyne)