Anglers on a Co Antrim river hit by hundreds of pollution incidents say Northern Ireland needs an environmental protection agency that would make “the polluter quake”.

The Sixmilewater suffered one of its most serious fish kills last month, when a suspected spill on one of its tributaries wiped out thousands of fish.

But prior to that there had been almost 300 pollution spills on the Sixmilewater and its tributaries in the last six years.

Most of those incidents have been classed as on the low end of the scale, but the number of repeated spills have raised questions about legal protections — less than £5,000 in fines have been issued for the 292 spills since 2003. Six prosecutions are still pending.

“We don't feel that there is adequate protection,” said Sam Andrews of the Antrim and District Angling Association. “Not just for our river but for the environment of Northern Ireland.

“Northern Ireland is devoid of a responsible environmental protection agency that has bite and makes the polluter quake.”

The recent kill on the Sixmilewater is believed to have started on the Ballymartin River, a tributary that runs close to Mallusk's industrial estate.

Thousands of trout, eels and other fish were found floating in both rivers.

“It was one of our worst kills ever,” said Mr Andrews. “It cleared everything in its path. Otters had returned to the river but no one's seen them since.

“A river's an ecosystem, continuously evolving, replenishing itself and renewing itself.

“But if you kill what's in that system it takes years to recover. Insect life, fish life in all it stages are wiped out and the system has to evolve again.

“That's what we're up against. Salmon and Lough Neagh trout will return to spawn soon. Because the pollution was so intense, when those fish hatch into small fry next year, they're going to depend on the ecosystem to feed them.

“But there will be nothing for those little fish to feed on.”

Mr Andrews said anglers are organising a public meeting next month with other wildlife agencies to seek a long term effort to resolve the problem.

“We're always left to pick up the pieces,” he said.