Flank marks on sea trout?

Rhithrogena

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I would have remembered if it had managed to do any wrapping at any stage.
It's interesting for sure. I think it is very likely caused by the leader though. The fish turns quickly, the leader gets caught under the fin (dorsal, pelvic, anal) and the pull from the angler drags the fish round, or the fish lunges away, which causes the marks. I don't think it would have to roll up in the leader for it to happen, just a partial wrap if you will, the leader rubs some scales off, and the marks are the result...
I reckon if we start looking for this damage regularly we'll notice it is sometimes only on one side or the other, which would eliminate any predator or net damage to my mind.
So let's look for the marks and snap both flanks of the fish on afflicted examples.
I have found lots of photos of fish with similar marks. If you look closely most do to some extent, it seems...
 

Cap'n Fishy

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It's interesting for sure. I think it is very likely caused by the leader though. The fish turns quickly, the leader gets caught under the fin (dorsal, pelvic, anal) and the pull from the angler drags the fish round, or the fish lunges away, which causes the marks. I don't think it would have to roll up in the leader for it to happen, just a partial wrap if you will, the leader rubs some scales off, and the marks are the result...
I reckon if we start looking for this damage regularly we'll notice it is sometimes only on one side or the other, which would eliminate any predator or net damage to my mind.
So let's look for the marks and snap both flanks of the fish on afflicted examples.
I have found lots of photos of fish with similar marks. If you look closely most do to some extent, it seems...

So, why would I only be noticing this on sea trout from Loch Hope (plus one from Loch Shiel), and not noticing the same thing happening on all the many hundreds of rainbows and browns we catch on all the other waters? Or even on sea trout from Loch Lomond or South Uist? I looked through all the photos I have of sea trout from there and none had the same marks.
 

mhw

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Had a look at my gallery of Loch Hope sea trout going back 10 years and many feature the marks that Col has brought to our attention
None of the marks are any more than discolouration ie none are wounds
Maybe not significant but no evidence on really fresh fish
Just wondered if it could be purely pigment change as the fish started to change colour
Martin
 

loxie

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If you look at the fish carefully it's clear many of the marks are scars and old, healed scars at that. I would not be surprised if some are years old. Leader damage is just superficial, removing a few scales. There are a lot of fish that run that river system and a lot of predators having a go.
 

aldot

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Alan, was the top fish still alive.....it looks as if the front end of it has already been soaking in the birds stomach acid for a good while.?
I walked into sight of that bird as I arrived at our water. It was in the process of hopping on to a platform. It spotted me from quite a distance, and 50% of the fish was visible, the rest was in the birds throat so not swallowed as such. It immediately released the fish and flew off. The trout was still moving when I got to it so I despatched it.
I'd saw that same bird before; its modus operandi was to catch a fish in the same generic area and hop on the platform to consume the fish, doing so all in one smooth operation (hence the 20ish second guesstimate).
I do remember that by the time I took a photo of the fish to show the other guys (10/15mins later), the head and shoulders had 'bleached' out a lot, so my guess is that the trouts head had been exposed to strong acid even within the birds gullet or upper stomach. It was never fully swallowed at any time, you can see that the colour is fully preserved rearwards of the shoulders.
 

bobmiddlepoint

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I've just had a look back through some of my sea trout pictures and the one place I've see a fair number of similar marks is on the Dorset Frome. I'm not aware of a predator that is peculiar to Poole Harbour and Loch Eriboll so that doesn't get us any further forward!

They are not line/leader marks and as Loxie says they are clearly scars (breaking the skin on some fish) and some of them are old scars.

The other thing I wonder is if sea trout scar more easily than browns, I've seen very few browns marked like this. We all know that in some areas they have soft mouths when fresh run and that the scales fall off them very easily when they are fresh and have been growing fast. Is it simply that minor scrapes and failed predator strikes leave more of a mark on fresh sea trout?


Andy
 

aenoon

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If you look at the fish carefully it's clear many of the marks are scars and old, healed scars at that. I would not be surprised if some are years old. Leader damage is just superficial, removing a few scales. There are a lot of fish that run that river system and a lot of predators having a go.
Had another look, and enlarged them all. Is only one that I could even suggest was a scar! It has a small spot that might be a scar.
All the others show minor superficial scale damage, and discolouration, all the spots are still there, as are scales, and obvious. That means skin was never broken, therefore no scar tissue!
Same damage can be caused by catch and release of ressie trout, but given these are all wild sea trout is unlikely the cause.
Which leads back to the thought that damage is self inflicted whilst running the river!
 

loxie

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Had another look, and enlarged them all. Is only one that I could even suggest was a scar! It has a small spot that might be a scar.
All the others show minor superficial scale damage, and discolouration, all the spots are still there, as are scales, and obvious. That means skin was never broken, therefore no scar tissue!
Same damage can be caused by catch and release of ressie trout, but given these are all wild sea trout is unlikely the cause.
Which leads back to the thought that damage is self inflicted whilst running the river!
You must be looking at different pictures to me!!
 

loxie

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Then in that case its damage caused getting over weir at Hope bridge.
There isn't a weir at Hope bridge. There's a croy on the right hand bank that constricts the flow but there is no obstacle to fish running.
 
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bobmiddlepoint

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Any Merganser/ Goosanders about there Cap'n ?

Plenty along the north coast but I’ve never seen them attempt to take adult fish. They stick to fry, parr and smolts (plus marine tiddlers). Of course some of the old scars could be from old sawbill injuries when the fish were part/smolts.


Andy
 

Rhithrogena

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I am pretty confident in myself that this is leader damage. Superficial grazing, mostly. The second pic looks a bit more than that, though? Fish often turn quickly and hook the dorsal or pelvic around the leader - it causes those horrible jerks you get when the line frees from the fin. The dorsal and pelvics are sometimes split by the leader when this happens, surely you've all seen this damage?
 

loxie

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I am pretty confident in myself that this is leader damage. Superficial grazing, mostly. The second pic looks a bit more than that, though? Fish often turn quickly and hook the dorsal or pelvic around the leader - it causes those horrible jerks you get when the line frees from the fin. The dorsal and pelvics are sometimes split by the leader when this happens, surely you've all seen this damage?
I have, many times. I don't think these marks, or most of them, look anything like that sort of damage.
 

Rhithrogena

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I have, many times. I don't think these marks, or most of them, look anything like that sort of damage.
The only real way forward with this is to make detailed close-ups of the damage, to see if it is restricted to one flank or both, and during the play of the fish, to note if there is any jerking or jinking that might be leader wrap in the fins.
The fact that some of us see very minor damage, and some see deep scarring shows we need to make notes on the type of damage at the time of capture, and record it with decent macro shots.
Without this it is all interesting conjecture.
For what it is worth here are shots of fish I have had which show what I think is similar damage, just not as pronounced. I think you see where the leader has rubbwd a line of mucus off the fish and caused grazing in a line from the base of a fin obliquely across the fish, often towards the base of another fin.
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loxie

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I agree they all look like superficial damage, possibly from the leader, but they bear no relation to the damage in fish 1,3,4 and the last one in the OP. They all show much more serious damage and healed scarring. I don't think Col's selection have a single cause either and other than definitely not being net marks or running marks I would be fairly open minded as to cause. A couple could plausibly be leader marks but they just don't seem that way to me. The fish below shows what I consider classic leader damage and also I like to post this picture whenever an excuse arises!

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Rhithrogena

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I agree they all look like superficial damage, possibly from the leader, but they bear no relation to the damage in fish 1,3,4 and the last one in the OP. They all show much more serious damage and healed scarring. I don't think Col's selection have a single cause either and other than definitely not being net marks or running marks I would be fairly open minded as to cause. A couple could plausibly be leader marks but they just don't seem that way to me. The fish below shows what I consider classic leader damage and also I like to post this picture whenever an excuse arises!

View attachment 43344
Nice fish!
Agreed re: leader damage here.
I just don't see any scarring on Col's pics. They all look superficial except for one, maybe....
 
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