We caught the meat at Willard today.

[Paddler]

My  guess is a cloud of newly hatched shad.  About the right time.  They start spawning by mid to late April and the spawn may extend through May.  Once the shadlets reach about 1 - 1.5" they start to become prey and the predators have more to eat and are slower to hit lures.  That usually starts after about the first of July.

Don't the newly hatched shad usually stay close to shore or around some cover, until they get big enough to be swimming out in the open water? When we saw something similar last week Alan wondered the same thing but I thought it was too early as well. Not that they could't have spawned already, just that they would be out in the open water already.                                                    I just googled it and gizzard shad spawn at 64-70 degrees, so the temps are right.

If you super-googled you would have also found that shad can and do spawn in water just above the mid 50s...and that the eggs hatch within about 3 days.  And, while most spawning occurs in shallower water, the young do not seek shoreline cover after hatching...as many other species do.  They are plankton feeders so they move out into the main lake seeking out concentrations of their fave groceries.  But, they do tend to maintain tight schools.  Initially these will show up as colored blobs...even up and until the reach larger sizes.  By mid summer the baby shad have grown to 2" or so and the "shad balls" on your TV will be bigger and denser...but still cohesive.  Only after the shad have reached several inches in size do they break up into small groups or even stray individuals...until they meet a wiper or walleye.

Good info Pat, guess that is what we are seeing then, especially since they can spawn at those colder temps.

Makes sense.  I wasn't seeing the larger schools that are smooth on top, rather a band of smaller, orangish individual blobs that are quite a bit smaller than a gamefish arch.  But like I said, it could be an area of higher plankton concentration that would attract shad fry, which would attract walleye.  A fine mesh net could answer the question.  

All I know is if I see it again, I'll waypoint it and work through it a few times.