In this area of the Midwest Bass will spawn during the full moon in May, or if there is two full moons in may some fish may spawn during one moon phase and the rest during the second. They also may spawn during the new moon cycle, or if there is two some may spawn in one phase and the rest in the other. It all depends on weather and water temperature. Usually its the third week of May, weather it be a full or new moon. These moon cycles last for 7 days, starting three days before and lasting until three days after. Some fish may spawn during the half moon which lasts for two days. On the Mississippi River you can watch the Carp splashing and spawning during the moon phases and that tells the story as to what the Bass are doing. The Carp may even still spawn in June and July and some Bass may do the same thing.
The best fishing is during these moon cycles, they have a huge affect on the fish’s attitude. They rest when there is no moon, feed and protect nests when there is. Once they spawn the fishing can get tough for a few weeks, only getting strikes from fish protecting their nests.
In this area of northern Illinois, which includes Lake Erie, the Bass spawn when the water reaches about 62 degrees which is usually the third week of May. Sometimes all the fish spawn at once, but years like this year when the full moon is around the end of the first week of May, the fish may not all spawn at once. The Walleye spawn in March and/or April and they too do not always spawn at once. I have caught Walleye in May that still had eggs while fishing Lake Erie. Northern Pike and Muski spawn in late February early March. The hybrid Muski found in some lakes do not spawn at all. The Catfish spawn in June and/or July. Bluegill spawn around the same time as the Bass or a couple weeks later and the Crappie spawn the same time as Bass or two weeks before.