It's autumn again, the air and water are cooling. The first frosts are due this week.
At this time of year the pike in my local reservoir (Poulaphouca, Blessington, Co Wicklow) are gradually moving from generally the 15' to shallows range, down into the 10' to 20' range.
I would guess today the majority of Blessington pike were lying up in 15-18' dormant/resting and moving into 12' to feed.
A map of the lake area prior to flooding is very useful in figuring out this lake.
Their preferred prey in Blessington is perch and they orient according to perch shoals. Although roach and trout are undoubtedly taken, they are not the species to follow if you want to find the bigger pike concentrations. I would definitely say that it's a good idea to study perch migration habits and temperature if you are a pike angler.
The Float Tube Ireland website has a page on making your own fishing maps using sonar fishfinders and GPS These techniques work very well on Blessington, and similar reservoirs.
Later on when the coarse fish move to the deeps, I will start paying a bit more attention to the location of the roach shoals, for my pike location, but not just yet.
Maybe in a month's time the roach will be tightly packed in deep water, tight enough for some big pike to move off perch shoals, for the winter months.
Note: I'm not saying pike don't like roach. it's just that when roach and perch are together in a water, and the roach are in open water, and the perch in cover like eg a field of old tree stumps, the pike prefer hunting in cover. Maybe they are more successful because of it, or maybe they just prefer the cover themselves.
Anyway, it takes time to develop angling techniques that work well in snaggy ground, but when you have them these are better places to fish usually.