Skip to content
Engaged

Massive Fish Death Estimated at Over 46,000, According to Cork Fishing Groups

Over 46,000 fish may have been killed in the River Blackwater in County Cork, according to fishing enthusiasts, who label this event an "ecological catastrophe".

,   and  ASMedia
2 min read
Thousands of fish deaths estimated at over 46,000 by Cork fishing groups
Thousands of fish deaths estimated at over 46,000 by Cork fishing groups

Massive Fish Death Estimated at Over 46,000, According to Cork Fishing Groups

Massive Fish Kill in River Blackwater: Toxic Chemical Spill Suspected

A tragic fish kill in Co Cork's River Blackwater has left over 46,000 fish dead, and the potential cause is under investigation. According to independent scientists and Inland Fisheries Ireland (IFI), the suspected culprit is a toxic chemical spill, likely from industrial or agricultural runoff.

The fish showed severe necrosis and eye damage, indicating exposure to an environmental irritant. Initial speculation about fungal infection, disease, low water flow, or high water temperature has been discounted by preliminary Marine Institute tests, which found no bacterial infection or systemic disease but environmental irritant damage.

The IFI is currently investigating the fish kill, and expects to receive test results from samples taken by the Marine Institute in 20 days. Preliminary data captured by IFI, EPA, and Cork County Council indicate no evidence of pollution or harmful discharges.

The affected fish species include stickleback, trout, salmon parr, adult trout, dace, roche, salmon, fresh water eels (an endangered species), and others. Conor Arnold, chairman of Killavullen Angling Club, is seeking written directions from IFI on how to manage the river until the cause of the fish kill is found.

John Ruby, chairman of the Mallow Trout Angling Club, is anxious to find the source of the infection as soon as possible. Minister of State for Fisheries and the Marine Timmy Dooley has expressed "great concern" and "upset" among fishermen due to the fish kill in the River Blackwater. He has been in touch with IFI and other agencies for investigating the incident.

Regarding timing, test results to definitively identify the chemical cause were expected within the same week as the report dated August 26, 2025, so definitive results may be imminent or already available shortly after. When temperatures reach 22C or 23C, it could lead to the death of trout. Another potential reason for the fish kill could be reduced oxygen levels in the water due to the enrichment of nutrients over a prolonged period.

The IFI has identified potential concerns around a fungal infection in the fish. However, it's important to note that the fungal infection may be caused by the fish being in a stressed state, possibly due to low water levels or increased temperatures.

Mr Dooley stressed that all potential reasons for the fish kill, including temperature and oxygen levels, are under investigation. He mentioned that the information flow to the anglers in the area from the agencies is something he has been trying to improve. Arnold and others are also calling for the test results to be published when they are available.

In summary, the leading hypothesis is a toxic chemical spill causing environmental irritant effects, with clear signs that definitive chemical identification results should be available within days to weeks following late August 2025. The IFI and other agencies continue investigations to identify the source of the chemical spill and manage the river until the fish population recovers.

Read also:

Related

Latest