Rising water temperatures can lead to ‘unavoidable’ kills

Fish kills caused by the heatwave “may be unavoidable”, according to experts, if the hot spell of weather continues.

The unusually hot temperatures have created conditions on Galway’s lakes and rivers that make it more likely for oxygen-starved fish to die.

There have been no reports yet of fish kills but Inland Fisheries Ireland (IFI) said it is “concerned with extremely high temperatures and low water levels that they could happen anywhere at any time.”

IFI has issued an alert to the public to report sightings of distressed fish.

A spokesperson explained to the Connacht Tribune that the alert applies to all fish, but salmonid fish species – salmon and trout – are particularly vulnerable once water temperatures go above 20 degrees centigrade.

“A combination of low water levels and high water temperatures can result in fish kills. In hot temperatures algal growth increases significantly, which can result in very low oxygen levels in the water at night when the plant undergoes transpiration and can starve fish of oxygen,” said a spokesperson.

IFI is asking anglers and the general public to report any sightings of distressed fish which may be caused by high water temperatures and low water levels. It is also asking anglers to voluntarily cease using ‘keep nets’ during this period to avoid causing unintentional distress to fish kept for long periods.

The state body said its staff will continue to monitor water bodies for any signs of distressed fish in shallow water but will be able to react more quickly to timely reports received.

Dr Ciaran Byrne, CEO of Inland Fisheries Ireland, said: “Low water levels and high water temperatures may lead to fish kills. The temperatures are dangerously hot at the moment and fish kills may be unavoidable. In some instances, moving fish may prove too stressful. We would ask anglers practising catch and release fishing during this hot spell to consider taking a break from fishing entirely until conditions are more favourable.”

IFI is reminding landowners, industry and farmers that as these low water levels and warm water temperatures put additional pressures on Ireland’s watercourses, there is a reduced amount of oxygen in water. As a result, poor quality discharges to rivers and lakes, such as silage effluent or sewage discharges can put additional demands on the oxygen levels, resulting in pollution incidents and fish kills.

Reports can be made confidentially to its 24-hour hotline 1890 347424 or 1890 FISH24.