Jed ... if you only have Black Crappie in your waters, like the one you're holding in the pic .... then water clarity can be a factor, as they prefer clearer water to spawn in. They also will come to the shallows earlier, and stay there longer than White Crappie. (even after the bulk of the spawn has taken place) White Crappie, on the other hand, prefer a little more murky water conditions (& slightly warmer water conditions).
Crappie will generally "try" & have their spawn, even under less than ideal conditions. But, they can & will pull off from spawning attempts, if the water temps get too high, too quick, or if the water clarity is not conducive to any possibility of success. They would, then, just return to deeper water & consume the protein content of the eggs/milt, as food. It's instinctive for them to try & produce another generation, but also instinctive for them to consider their own survival, first.

... cp