Trout stomach contents : surprising

shortcircuit

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I was fishing a favourite spot of mine that is particularly good in summer because there is a nice riffly flow of water in the centre of the run and smoother water either side. This evening there were olives and sedges hatching in this run and a good pod of fish rising.

I caught a decent size fish on a size 14 balloon caddis and I decided to keep him for my lunch the next day (these are wild fish and I would only take one or two fish the entire season).

So when getting the fish ready for the grill, I decided to inspect the stomach contents, expecting to see olives or caddis or both. Not a bit of it.
The trout's stomach was stuffed with tiny olive coloured nymphs/larvae. These were really skinny and had no clear distinction between thorax and abdomen and were about 4mm long (about a size 18 or 20). Pic below. Among the thousands of these, there was one solitary fat caddis pupa.


20210722_133605 (2).jpg


Am I right in thinking these have to be midge larvae?
If so, I find it a really odd occurrence. Round here, I would never hear tell of anyone fishing a buzzer in a river. Sometimes people might fish an adult midge imitation like a Griffith's Gnat or a small black F Fly, but sub surface it would be all PTNs and hare's ear nymphs.

The other thing is that this fish was taken in reasonably fast water with a stony/gravel bottom. My understanding was that midges are more likely to hatch out from silty bottoms with slow/calm water.

Would be interested to get people's thoughts on this one!
 

PaulD

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It's fair to say that, in the UK, chironomid larvae / pupae imitations are notably under used and under rated patterns on our rivers compared to their usage in the USA for example.
 

iainmortimer

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They certainly look like midge larvae to my untrained eye and I would imagine that given the proliferation of midge/mosquitoes around most rivers. throughout the year, that they form a substantial part of most fish diets in running and still water.

However, I guess because they are small, fish are more likely to home in on bigger flies unless there is a good hatch that makes them worthwhile. A bit like us being impressed by a steak or cottage pie but unlikely to being encouraged to the table by one or two strands of mince however well presented!

It may be that there has been a good midge hatch which the fish have capitalised on as the larvae were washed downstream.

I suspect that many small olive quill nymphs are actually taken as midge larvae rather than olive nymphs.
 

pati

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I was fishing a favourite spot of mine that is particularly good in summer because there is a nice riffly flow of water in the centre of the run and smoother water either side. This evening there were olives and sedges hatching in this run and a good pod of fish rising.

I caught a decent size fish on a size 14 balloon caddis and I decided to keep him for my lunch the next day (these are wild fish and I would only take one or two fish the entire season).

So when getting the fish ready for the grill, I decided to inspect the stomach contents, expecting to see olives or caddis or both. Not a bit of it.
The trout's stomach was stuffed with tiny olive coloured nymphs/larvae. These were really skinny and had no clear distinction between thorax and abdomen and were about 4mm long (about a size 18 or 20). Pic below. Among the thousands of these, there was one solitary fat caddis pupa.


View attachment 41592

Am I right in thinking these have to be midge larvae?
If so, I find it a really odd occurrence. Round here, I would never hear tell of anyone fishing a buzzer in a river. Sometimes people might fish an adult midge imitation like a Griffith's Gnat or a small black F Fly, but sub surface it would be all PTNs and hare's ear nymphs.

The other thing is that this fish was taken in reasonably fast water with a stony/gravel bottom. My understanding was that midges are more likely to hatch out from silty bottoms with slow/calm water.

Would be interested to get people's thoughts on this one!

looks like a small slim pheasant tail would be ideal…
 

shortcircuit

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402

Bingo!

I had arrived at the same conclusion. I neglected to mention that there was a big tangle of green stringy weed in the trout's stomach too. I then realised the trout must have spent its day nosing in the weeds for food. I then wondered to myself "could this be reed smuts" , something I had heard of from time to time.

After googling reed smut larvae, I got a picture just like what you have given a link to. The giveaway is the bulge towards the tail which I definitely observed in my specimens.

So this trout was filling himself on tiny reed smut larvae all the time, and yet he took my (relatively) huge adult caddis. He definitely was an opportunist
 

shortcircuit

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looks like a small slim pheasant tail would be ideal…

They are more curved in real life than the photo shows. They are also really slim. If you were to try and imitate, I think the best representation would be an 18-20 olive buzzer pattern without cheeks/ breathers
 

raphael

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France, near Sancerre
Yes that's Simulidae larvae. There are some places where they are the main source of food for trout especially where the original entomofauna switched to something more suited to slightly degraded water.

R
 

shortcircuit

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Yes that's Simulidae larvae. There are some places where they are the main source of food for trout especially where the original entomofauna switched to something more suited to slightly degraded water.

R
Interesting point. Odd here because the river I fish is in quite good condition and has excellent hatches of BWOs and caddis
 

Fishtales

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Interesting point. Odd here because the river I fish is in quite good condition and has excellent hatches of BWOs and caddis
It could just be that there are now bottom feeders feeding on them and that was one you caught and why it had a caddis in its stomach too.
 

Whinging pom

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The British ones I think are a bit different to the link. The females make black widows look quite tame. How I remember being told the story
( are you sitting comfortably, then I’ll begin)
When they come to mate the the tiny male who has webs coming is out of his forearms like a cross between Spider-Man and Popeye, he carefully wraps up in silk a grain of pollen and gingerly presents it to the female to pacify her aggression.
Some of the cheeky males cheat and wrap up a little piece of grit. When he presents the package to the larger female she starts to unwrap it while he goes around the back to attempt to mate. If big mama opens the package and it’s not pollen or she’s not suitably impressed she turns around and with a long piercing mouthparts and stabs him right through the head.
And she lives happily ever after!
the end
 

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