The same reason aquaculture doesn't work on American Lobsters.
They would have to house them individually and that makes it cost prohibitive.
Thanks for the report booman
They actually do that on a small scale in Bar Harbor Maine. Check out the PVC "rooms" for the lobsters when they are sized right. When smaller they are in giant vats.
it is either non-profit or state run- I forget. Mount Desert Oceanarium. The local lobsterman are allowed to bring in females with eggs to this site so that they can raise the babies until they are about juvi bite size...and released back into the wild. It's faster and hopefully bypasses a lot of the loss the baby lobsters endure.