This morning we received a call from a ghillie on the middle river reporting a salmon had been caught with head lesions. As there is a PhD student in Stirling who has requested tissue samples from fish like this, Brian and I drove down to have a look with the required kit for taking samples.
The ghillie had kept the fish alive, and it was a fair sized one estimated at about 12-13lbs. The angler who had caught this was understandably disappointed that the fish was diseased. We sadly had to kill the fish, and got underway with the required samples. Samples of blood, skin, the lesions themselves, and many of the vital organs were taken and put into various types of fluid to preserve them during transit to the lab. As it was a hen fish, when we opened it up there were eggs beginning to grow inside, and we decided to take them out and see if we could estimate how many eggs it would have laid. There were 106g worth of eggs, but as you can hopefully see from the photo, the eggs were underdeveloped and couldn’t be counted individually. However from a fish this size, we would probably estimate there would be 6-10,000 eggs. It was a shame to have had to kill such a large fish with so much spawning potential, however the lesions were covering a significant proportion of its head and it most likely wouldn’t have survived anyway. Additionally, it is hoped that these vital samples will help to understand the cause behind the lesions, and help to prevent them reoccurring in future runs of salmon.