Salmon poachers dropped a concrete block on to a patrol boat from an overhead bridge as part of an escalating campaign of threats and intimidation against bailiffs in Northern Ireland, it has been revealed.
Gangs of criminals stoned cars and also confronted Loughs Agency staff with knives after being challenged while using nets to fish illegally.
Agriculture and Rural Development Minister Michelle O'Neill is due to meet PSNI Chief Constable Matt Baggott next month to discuss police efforts to end the worsening violence in the Foyle and Carlingford areas.
She said: "Staff should be able to carry out these duties without fear of intimidation or assault."
Poachers can make between £8 and £10 per pound for spring and early summer wild salmon - bought by dealers and sold off to restaurants and hotels, some in the Republic.
Seamus Cullinan, an agency inspector whose area includes the Mourne and Finn rivers, claimed the poachers, wearing scarves and balaclavas, were more violent than ever.
He said: "It seems to have escalated. They are more militant and quicker to resort to violence, especially at the height of the season when the stone attacks happened almost nightly."
A stretch of waterway between Sion Mills, Co Tyrone, and Lifford, just across the border in Donegal, is particularly dangerous for staff on the river banks, but there have been confrontations as well in the middle of Lough Foyle as the poachers go in search of oysters and mussels.
The concrete block was dropped on an agency boat from Porthall Bridge, near St Johnston, Donegal, last year. Nobody was hurt, but staff claimed they were fortunate to escape uninjured.
Poachers are also producing knives to threaten and frighten staff and other bailiffs who work for fishing clubs.