Honestly think it's just an adaptation, on a lake by lake basis, for thriving survival. Some primary food sources are possibly more active at night, the main predator (Pike) may be fairly inactive, less pressure from us......... Not sure what the exact reason is, simply know it exists on a couple bodies of small(ish) waters I frequent. A mixed bag of nice Perch, 'gills and Crappie is a great night. And yes these are my primary Pike waters during open water, 30" - 40"+ are there with a bad attitude, they are left alone on ice. These balanced lakes that I've fished since the 60s are basically unchanged since then. Even the large breeder sized pannies go back down the hole, lakes are small, misunderstood by locals and well balanced --------- > it shall stay that way.