Moribund sea trout

I got a call yesterday afternoon to say that a sea trout with a head lesion had been caught and retained alive. This sounded like a good opportunity to collect samples for the UDN student at Stirling so we headed downstream to investigate. The fish was still alive and it turned out that it had been found dying in the shallows. At first I couldn’t see any marks on the head and the ghillie started to doubt either his or my sanity but sure enough when viewed under water the mark on the gill cover was obvious.

Mark on gill cover not so obvious out of water

Mark on gill cover not so obvious out of water

The damage to the gill cover was not serious so we examined the fish carefully for other causes of death. There was a small mark on the leading edge of the dorsal in and another mark on the tail but again nothing terminal. There was however an external mark on the side of the belly where the scales were raised with what looked like inflammation of the skin. I had seen this sort of mark before on farmed fish and had noted internal haemorrhaging in the muscle during vets examinations.

External mark on belly of fish.

External mark on belly of fish.

Internal muscle haemorrhaging at site of external mark.

Internal muscle haemorrhaging at site of external mark.

The internal haemorrhaging could have been caused by a bruise but I suspect some sort of infection. Anyway at a low level of incidence it is nothing to be concerned about.

We completed all the samples required by the student including a 5mm blood sample extracted by syringe from the tail of the fish. The fish weighed about 3lb and was a male. Scales were collected for ageing.  That is the second Spey sample submitted for the UDN research; we got a salmon from the Avon two weeks ago. It has been a struggle to get samples this year, last year I could have got them most days. There have however been more dead fish in the river this spring, although numbers still low overall.

Apologies for the flurry of blog posts this morning, we got a new pup three weeks ago, a cocker spaniel and dog proofing the house and garden has kept me busy in the evenings. “Rogie” is a nice quiet dog, typical of his breed!!

There are 2 comments for this article
  1. Stephen Brennan at 7:04 pm

    Nice seatrout Brian pity about it’s demise any possibility the damage was caused by poor c&r technique

    • Brian Shaw Author at 4:03 pm

      Hi Stevie,

      Good to hear from you. Possibly although I couldn’t see any damage to its mouth. There was a sea lice on it so it was pretty fresh. I sent the samples away for the UDN project but she may find other problems with it.
      Cheers
      Brian

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