Several hundred dead fish surface at Sheelin

Second major fish kill in two weeks - pollution incident suspected

Several hundred dead brown trout have surfaced at Lough Sheelin in a second fish kill incident reported in the county a fortnight.

The major fish kill was initially detected by a member of the public on Wednesday, July 16, at an area known locally as ‘Captains Bay’ where the Mountnugent River feeds into Sheelin.

The Lough Sheelin Trout Protection Association (LSTPA) said they are “extremely disappointed and concerned” by the development.

The Sheelin fish kill follows an incident the previous week in which a suspected pollution incident killed over 1,000 fish in the Ballinagh River, which is part of the Erne catchment.

LSTPA had initially estimated that “at least” 100 adult wild brown trout had died as a result of the Sheelin incident, some weighing up to 10lbs or 4.5kg.

“Those fish would be regarded as trophy fish by anglers all over the world,” lamented Eamonn Ross of LSTPA, speaking to the Celt on Thursday.

“The initial estimation of fish killed is probably an underestimation given the nature of the area and previous experiences of fish kills on the catchment,” added Mr Ross.

Sadly he was proven correct.

Inland Fisheries Ireland (IFI) originally reported they had recovered 68 dead fish from the site; including 63 brown trout, two roach, one perch and two stone loach. However this week IFI revised that number upwards saying there were “several hundred additional mortalities”.

“These fish had sunk to the river bed upon expiration and were not visible in recent checks of the river bed, until decomposition caused them to float to the surface.

“These additional mortalities were in the lower reaches of the Mountnugent River in the last 400 metres before it enters the lake. There have been no detections of any new fish in distress since the time of the initial report of the fish kill.”

IFI believe the fish kill was caused by raised temperatures. A video taken last week appeared to show trout at Captains Bay displaying distressed behaviour.

“It’s typical of fish who are having difficulty breathing,” Eamonn explained of the footage.

LSTPA describe Mountnugent River as “a critically important” spawning tributary for Lough Sheelin.

LSTPA is eager to stress how they are not blaming anyone for the Sheelin incident. They recognise the recent warm weather poses a risk, however, they also believe this is not solely a “natural phenomenon” due to high temperatures.

“Something triggered increase in bio-oxygen demand (BOD) that resulted in less oxygen for the fish. We don’t believe that’s fully down to higher temperatures, having said that we don’t have any evidence of that other than we’ve seen high temperatures before and have never seen anything like this happening.

“The fact it happened at the mouth of the Mountnugent River would indicate to us that some increase in nutrient load triggered an increase demand for oxygen and that resulted in the fish kill,” Mr Ross surmised.

Monitor

IFI is conducting an investigation and assured the Celt its officers are continuing to monitor the Mountnugent River and Captain’s Bay area.

“Investigations thus far have not yielded any evidence of pollution,” an IFI spokesperson told the Celt.

“IFI officers will continue to examine and assess the entire site during the coming days to establish if any more deceased fish are in the water.

“IFI suspects the event was caused by high water temperatures in combination with low dissolved oxygen levels, exacerbated by the presence of aquatic plant growth (which remove oxygen from the water at night during respiration), which impacts on larger fish disproportionately.”

LSTPA note it takes very little increase in nutrient load to have a major impact on the lough given the current conditions.

The LSTPA is asking that all necessary precautions are taken to ensure that waste disposal, which could end up in rivers and lakes, is avoided. This includes ensuring that all current regulations are monitored and policed.

“The LSTPA call on those responsible for ensuring safe and clean water in the Sheelin Catchment to take whatever measures are necessary including inspections and audits of all discharges to the lake to ensure that incidents like this one are prevented from recurring.”

Meanwhile test results following the Ballinagh River fish kill are due back in the coming days as a separate investigation continues there.