[PDScott]

I am sure that we have all experienced the situation - the sun comes out, the fish disappear from the surface. When the cloud cover returns, the fish are up again. My question to those more knowledgeable than myself is whether the flies possibly stop hatching in brighter conditions because they are more easily seen. Does the light level trigger the hatch or is it just that the fish cannot look into the sun
The reason I ask this question is that I experienced this today at Pitfour and the reaction of the fish was almost instant - any cloud cover and the water was alive with fish but I could not see any changes in the amount of fly-life.
Any thoughts?
Peter

[Jim Eddie]

Peter

I always thought it was because fish have no eyelids and therefore can't look into the sun, I'm sure the insects will continue to hatch in the sunlight.


 

Jim

[Peter McCallum]

If they are genuine water bred insects (mayflies/midges etc)  they res t on the water to dry their wings before taking off...... so on a warm sunny day the wings will dry very quickly and the flies will  fly almost as soon as they hatch. Cloudy, damper weather - they take longer to fly. So what your probably seeing is fish feeding subsurface since the ascending nymphs/pupae will be a much easier target than the adults which are only there for a fraction of the time.

[Fadpasser]

Don`t think it changes the insects behaviour, always thought the fish just went that bit deeper with the bright sunshine due to the eyelid thing 

[Richard Tong]

I am not sure about the eyelid or lack of reason. I have seen big Trout on Don in April 2003 rising to a hatch of MB's in bright sunshine (this was week after week of similar weather and the MB's must have acclimatised to it). A Grannom hatch is triggered by sunlight and the fish go mad for them. Only last Friday Paul and I fished the River Eden in very blustery weather, which was also wall to wall sun...we found a sheltered pool where the fish were going crazy for Black Gnats blown onto the surface-the fish could/must have been able to see us but we caught  (wild) fish to 18" and played them with plenty of them causing a considerable disturbance...whilst the others continued to feed until eventually the activity got less with the amount of fish being played. Very weird and nether of us has ever seen anything like this;there must have been 20+ Trout on the go! This was very shallow water probably 6-8" deep and every Trout could be seen.

If the fly is available then the fish will respond. It's just that most flies that we have do not, for whatever reason(and their vulnerability/visibility could be a factor-perhaps Grannom get over this by hatching en masse), hatch in large numbers in sunlight I think. However falls of terrestrials does demonstrate that the lack of eyelids is not the reason that the Trout 'go down'


Richard

[Mike Barrio]

The trout's fear of the surface may possibly be down to a long term instinct, perhaps they have learnt of the danger of being more visible in bright conditions to aerial predators?

Best wishes
Mike

[Allan Liddle]

The fish will generally respond on the surface if there's something there to go for, so surface activity can be (and often is) still high during bright conditions.  Bright and windy can be very hard as the trend is for the target insects to simply get blown off the surface leaving little to stimulate the fish.  Terrestrials can counter this as Heather Beetle (out in good numbers this year), Heather Fly, Daddies and Cow Dungs can bring spectacular rises (although often very localised).

A regular flush of water helps keep the water borne insects active and big hatches possible, resulting in some good rises even in low water.  Very warm or low oxygenated water has an effect on the insects (and the fish).

Let's hope we're going to get a wee freshen up over the next few hours just in time for the weekend.

Allan

[BillyWallace]

Generally speaking I have found that wind, temperature and wave has more to do with the hatch dropping off on most waters ( please note I said most waters, we all know there is the exception to any rule regarding fishing). I know many waters where sunshine encourages the hatch and the trout feeding and long may that continue (P.S> Scotland needs more sunshine)