The spawn is not so much dictated by the moon. but fish do react to it. Length of day and average water temperature dictate the spawn more. Males show up on the spawning grounds first and females stage in deeper water nearby. When water temps and day length are right females start moving in and more spawning does take place at night. Mature older females will often spawn first, but smaller young females dominate the real early spawning. Egg quality in these are often not good. The heart of the spawn is when you see the old sows and those are the ones that impact the spawn and year class. Once started spawning can last three weeks, but the main spawn happens in just a few days (7-10 days) then a recovery period. After a recovery period they put on the food bag to recoup the lost energy of spawning and this is when your bite changes as they are feeding on anything that looks good, Earlier they were eating high protein diets of mostly forage fish to build energy.