Usk Salmon

‘Many of you have contacted me recently to report sightings of diseased Salmon in the Usk.

Firstly, I’d like to thank you all for your information thus far. Secondly, please continue to report your sightings and contact me direct on 07795811853 if you find any distressed fish. I will then make the decision to either provide advice and guidance to you or to arrange for the fish to be collected and transported to our laboratories for further inspection. Under no circumstances should you or any other member of the public remove the fish yourselves. I will make every effort to ensure my staff attend to assist.

Skin conditions of wild salmonids such as Ulcerative Dermal Necrosis (UDN) and other fungal infections are natural conditions that usually affect low numbers of fish as they return to freshwater. Some of these conditions remain poorly understood and can be attributed to changeable natural conditions such as temperature. This year has been very cold and could be a factor to consider. Coupled with the very hot/humid few days we have just experienced means a changeable climate which can exacerbate fungal and bacterial infections in our fish populations. Fish with UDN have skin lesions that often begin as round sores on the head. These lesions can occur at any time of the year and can heal without further complication. However, open sores can quickly develop secondary bacterial infections, increasing in both size and severity. UDN is sometimes confused or masked by these infections, making an accurate diagnosis difficult. Badly affected fish may die as a result of ulceration, fungal infection and loss of normal osmoregulation. Fungal infections are more likely to develop during prolonged periods of low flows. Fungal infections involving the head or body of salmon are most often the cause of common Saprolegnia infections, not UDN.

Thanks again for your reports and please do not hesitate to contact me with further information’.