More than 700 fish have been killed along the River Roe at Burnfoot, between Limavady and Dungiven, a local angler has said.

A spokesperson for the Departure of Agriculture, Environment and Rural Affairs (DAERA) confirmed a fish kill occurred in a tributary of the River Roe in County Londonderry on Friday evening.

Investigations are now underway, the spokesperson added.

Speaking to BBC News NI, Eamon Mullan, chairperson of Roe Angling Limited, said more than 700 juvenile fish, including salmon, sea trout and brown trout, were killed in the tributary.

Mr Mullan said Loughs Agency staff were alerted to the incident late on Friday evening and inspectors have been attending the scene in the days since.

“It’s a very, very substantial fish kill,” he said.

Mr Mullan explained that the tributary is a spawning area for salmon and a nursery area for juvenile fish, both salmon and sea trout.

He said the fish kill would have a “major impact” on the tributary for some years to come.

Agency staff have so far been unable to identify the source of the fish kill, according to Mr Mullan.

“They were looking for evidence to see what type of material might have caused the problem and so far they haven’t been able to determine that,” he said.

He added that agency staff will be on the river again on Monday to try to identify the source of the kill.

The River Roe fish kill comes after reports on Wednesday that hundreds of fish could have been killed by pollution in the Glenavy River in County Antrim.

The Northern Ireland Environment Agency (NIEA) received a report on Wednesday that several miles of the river – part of the Lough Neagh catchment – was polluted and that there were fish in distress and struggling to breathe.

About 30 dead fish were identified, but concerns were raised by local anglers that the number could reach 200 or 300 at that particular stretch of river.