Friday 23 August 2019

Mysterious skin disease threatens salmon in Irish rivers

Salmon from the River Corrib showing early signs of the disease
Salmon from the River Corrib showing early signs of the disease
Salmon from the River Boyne showing signs of red skin disease

Markus Krug

Salmon in Irish rivers are facing a mysterious new threat after several specimens were found with signs of bleeding and skin ulceration.

The first salmon with these symptoms in Ireland were found in early June and by mid-June there were reports about the disease in six rivers, both on the east and west coast.

"It is unclear at this time what is causing these symptoms. There is some evidence that the disease may become less frequent with rising water temperatures," said Dr Paddy Gargan, Senior Research Officer at Inland Fisheries Ireland.

The affected fish show signs of bleeding, ulceration and haemorrhaging along the belly, as well as the head and the tail.

Salmon from the River Boyne showing signs of red skin disease
Salmon from the River Boyne showing signs of red skin disease

"The salmon then often get secondary infections because they are weakened and their infected skin is exposed to fungus in the water," said Dr Gargan.

The scientist said that there was no danger in consumption of the fish as long as only the skin is infected during the early stages.

"When it gets to the stage where there are a secondary infections that have reached the flesh we would advise not to eat it," he added.

In regards to determine potential causes for the skin disease, the scientists are mostly looking at which salmons are affected.

"It is mostly large multi-sea-winter fish that we see with the infection, so we think that the water temperatures might be a factor."

Dr Gargan added: "There is also a suggestion that the disease is related to a change in salmon diet but this has not yet been established."

It is suggested that a deficiency from this change in their diet might be a contributing factor but Dr Gargan said that at this point that is "speculation with no concrete evidence".

To further gain knowledge about the disease, the Irish scientists are in contact with colleagues in other parts of the world.

"We have been in touch with the colleagues in Norway and Sweden. They are saying that there the symptoms are disappearing with rising temperatures, so this might happen here as well."

In addition to their own monitoring of the situation as well as their constant exchange with colleagues in Scandinavia, Inland Fisheries Ireland is calling for the public’s help.

"We are asking anglers and fishery owners to report any catches of salmon with these symptoms to us as soon as possible," said Dr Gargan.

Inland Fisheries Ireland has established a 24 hour confidential hotline number on 1890 34 74 24 or 1890 FISH 24 for everyone that wants to report a sighting or a photograph.

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