Mystery Roach

I had decided to spend last night on a gravel pit, with those gorgeous green tench and the slightly less lovely bream as the primary targets. No problems if a carp or two should get in the way of the peace and tranquillity of course. It proved  interesting,  with bream rolling all night, fairly near my groundbait,  carp splashing about in the distance, and with the odd tench ever so casually breaking surface close in amongst the prolific elodea pondweed.
 I had gone with the intention of photographing some little bank voles that had kept me company right through my previous night shift on the water.  I had not knowingly seen voles before, but didn't take the big camera last week, and so had the SLR in tow this time.  Inevitably, as a result, the bank voles made themselves completely absent for the whole night.  Not one appeared on the platform from where I fished.  But five or six wood mice darted about onto the open area, grabbed  morsels of groundbait and then returned to the grassy bank.
The mice most people are acquainted with are house mice.  I remember seeing them in my grandmother's terraced house.  She used to catch them in the kitchen.  None of these new-fangled traps for her.  She coated one side of a sheet of brown paper with treacle and left it on the floor.  In the morning the mouse would be trapped, its fur solidly glued to the treacle.  She would then wrap the mouse up in the paper, hit it with her solid cast metal flat iron, and consign its remains to the bin.  The house mice always looked very dirty creatures to me, but wood mice always seem to have a glorious sheen to their coats.

  Two Woodmouse Photos Taken Near My Feet
 

At times they stayed for minutes, confident that I did not intend to harm them, and the most in view at any one time was five within a yard of my feet.  They sit upright on huge pink hind legs when feeding, their big ears sticking up like miniature Sky aerials, whereas the voles I saw last time seemed to prefer being on all fours. The voles were also much slower, and I cannot help but wonder whether the owls, that are quite common in the trees around the lake, have fed well during the last week grabbing them as they leave their holes for the fishing platform.  Vole-au-vents?
I don't propose to describe the fishing here and now, but shortly after the first rays of daylight there was an unusual event.
To my right, and above some fairly deep water, maybe 20 feet plus, covering an area of at least 80 yards square, there were fish rising.  A lot of fish rising.  But the rises were almost all very splashy, and I suspect they must have been roach.  Much too small for carp, far too frantic for bream or tench, and the lake does indeed hold a good head of roach, as I had proved a couple of weeks ago. The splashy rises continued for  30, perhaps 45 minutes before stopping completely.
I have absolutely no idea what these fish were doing.   A local told me that the splashy rises happen almost daily, and certainly at this time of year.  There was little or no surface fly life, the lake was flat calm.  So what were all these roach doing? And why were the rises so splashy?  Why were they all congregated in that one area?  There were few, if any, elsewhere on the lake.  Had all the roach assembled in one area?  Or was it just in that area that the roach behaved thus?  Other areas of the lake have a similar character. It is a mystery that has me flummoxed.