manatees

Antillean manatees (Trichechus manatus)

Good evening everybody, I've noticed that manatees are only kept in two or three zoos/aquariums in the US outside of Florida. Is there a particular reason why so many US zoos and aquariums don't have manatees? Is it because of cost, laws, or something else? Thank you & excited to see the responses!

Even if you can almost barely make out their profile, I wanted to point out that they are actually two manatees in this photo rather than one, hence the reason why I pluralized the word manatee in the first place. This photo was also taken on September 5th, 2021 at Anna Maria Island, Florida.