He may be talking about "paper shell" rather than soft shell. A common farmed crayfish in Ohio is O. immunis. Probably that. You are right about soft shells, they are freshly molted.

Crays mate a lot, and even more when it cools off in the fall. Typically the ones in your neck of the woods won't berry until it grops below 40F water temperature for a few weeks. They would carry the eggs all winter and hatch in the spring.

To do the process artificially you would find berried females and slowly bring the water temps up into the 60's over a period of a week or so, just a couple of degrees a day. Adjusting the photo period from winter to spring over the same time helps. A jurry rigged chest freezer works nicely for this. They sell external thermostats for freezers to make lager beers that works great for this.