Since they are living things worth a lot you would think some clever fellow would find a way of growing them. The law must be stupid in this regard to prevent such a profitable venture.
There are commercial eel farms in the US. Two(?) in FL, Pennsylvania, and Maine. One in Deleware. One of the FL farms is located in the Keys.
and one was at Federal Point on the St. Johns River near Hastings. I live about a mile from the location.
Unfortunately, I believe it has been converted to pot growing. For the first 20 or so years after I moved here, the facility used outdoor cement ponds, covered in the winter with greenhouse framing. A friend who was the Army Corps of Engineering office head told me they were permitted for 6 million gallons of groundwater each day. Used once, then discharged to the river. This is typcal of non-recirculating farms.
https://www.agmrc.org/commodities-products/aquaculture/aquaculture-fin-fish-species/american-eel
I have no idea why the business closed. Most of their markets were Europe and Asia.