Besides teaching both single and double hand fly casting I studied aggressivity for asp during the last days.
For several species of fish I often saw the big fish taking over the best feeding spot while the smaller ones would have to stay within the less proper feeding spots. In a river this often means that for example the largest grayling or trout will be in that position where most insects will come by first. The smaller fish will have to wait for the food behind. In the end of the pool we often find the smallest fish unless there is a deep hole or something making for another special holding spot. The biggest fish mostly protects his area and spooks away all smaller fish trying to enter his area.
Another interesting observation I made with many different species of fish is that especially the predatory fish (like for example asp) are often having a feeding area and a resting area. I am pretty sure that those hunters don't want to spook their bait during none feeding times and therefore stay away. This holds especialy true for those fish that are moving a lot!
Now when fish are about to enter their feeding area we may try to imitate their food. Depending on the species of fish and the situation this can be very tricky, because yet we fly fishermen present our flies in all kind of weird smell signatures far off the real food. Sometimes this works and often not.
Some fish though may take (better test) our flies for curiosity. This can make for another proper strategy of course.
Then there is aggressivity. Imagine you are about to enter your feeding area or are already in it and first thing you see is someone else crossing that area and spooking away or even worse eating your food. This may be someone pretty small compared to you but much bigger than the food you are after.
Last week I was sitting at our harbour watching small asp for about several hours. They were entering their feeding area eating on very small stuff, like insect larvae in one spot and on very small newborn fish in another spot. I tried two different strategies. First one was with very small flies trying to imitate their food. I caught very few ones while having several fish coming close only to then turn away without taking my flies. Whatever it was they knew my fly wasn't for real. High speed was the trick to avoid every fish to turn off.
Then I took one of my wobbler flies. Having that crossing thru the feeding area I could see the bait moving away and the biggest asp of the group then would strongly attack that fly. No doubt the fly was way too big to imitate anything that asp would eat. Several times I could succeed with that strategy even in pretty low speed. Watching the area and I would exactly know which part of it belongs to the biggest asp. Forcing him into aggressivity clearly worked best.
The interesting thing is, that flies coming with less of an agressive movement made the asp come close and then they seem to realize the fly to leave the spot and not much happening anyway. But when the wobbler fly kind of destroys the perfect feeding situation, asp went mad and straight away bite it!
According to my experience and that of spin fishermen it seems pretty clear:
We can catch asp by presenting pretty small flies imitating their typical food or by forcing them into aggression by sending a significant destroyer into their feeding area.
No doubt I have seen similiar bevaviour for several species of fish.
Ok, time to go fishing again! ;)
Great fly fishing week to all of you!
All my best