As a local WL resident I would guess that these bream have a well-trained human who provides them with a regular feed.
Close to my home there are three generations of one family that have been feeding the bream at 4.00 pm each day for most of the 40 years I've lived by the lake.
The fish slowly sidle up to this house frontage, starting from about 2.30 pm each day, and after they've been fed they quickly disperse. They also seem to adjust to changing time zones as daylight saving switches On and Off.
Woe betide any innocent fisherperson who walks along the path having a flick: the reside