Inland Fisheries Ireland (IFI) is expecting that tomorrow it will receive the results of extensive laboratory tests on 28 brown trout impacted by the large fish kill on the Blackwater River last month.
However, the outcome of those tests will not be made public until after they are examined by the interagency group investigating the fish kill.
The bodies of 28 dead trout were being carefully examined for markers of any contaminants that might help determine the cause of the fish mortalities.
They were being checked for residues of heavy metals, chemicals, pesticides or other potentially harmful substances in the internal organs of the fish.
IFI said today the result may direct further steps in their investigation.
These latest tests follow on from the diagnostic testing of fish samples conducted by the Marine Institute on 14 August.
That earlier testing found no evidence of bacterial infection, systemic disease, or specific viral infections.
No evidence of a parasitic infestation was found either.
Nevertheless, gill pathology was consistent across all samples and suggested possible chronic exposure to a chemical agent in the days before the first reports about the fish kill were made.
Inland Fisheries Ireland said, in collaboration with other statutory partners, it is deploying a further range of operational activities to try to find the cause.
This includes additional habitat inspections on the River Blackwater to assess the scale of mortalities, and waters affected.
More than 110 habitat inspections at 45 locations have been completed since 11 August.
Drone and kayak patrols and now being deployed over an extended area of river to continue an examination and survey the scene.
IFI is also using historic fish population records to quantify the number of fish that may have died in the incident.
A survey to assess juvenile lamprey in the affected waters is also underway. This is a protected species of freshwater fish that lives in the river sediment.
The interagency group examining the fish kill was set up by the Minister of State for the Marine and Fisheries, Timmy Dooley.
It is being co-ordinated by the Inland Fisheries Ireland and includes Cork County Council, the Environmental Protection Agency, the Local Authorities Water Programme, the National Parks and Wildlife Service, the HSE, the Marine Institute, Uisce Éireann, and representatives from some government departments.
The group met for the fourth time yesterday and was updated about the ongoing work to establish the cause of the fish mortalities.
They will meet again at the end of this week to consider the extensive test results Inland Fisheries Ireland will receive tomorrow.
It is expected that the outcome of the tests will not be published until after that meeting has taken place.
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