The USA will not be the first nation to ban exploitation of cetacean (dolphins, whales, porpoises) species for human entertainment. In 2013 India's Ministry of Environments & Forestry declared cetaceans "non-human persons," banned their use in public entertainment and forbid them from being held captive anywhere in India.
The dolphin brain is comparable in size to the human brain. Furthermore, many cetacean species boast a neocortex (the part of the brain associated with rationality and judgement) close in surface area to, if not larger, than that of man. Many species also appear to have limbic systems (the part of the brain associated with emotions) arguably more sophisticated than man's own.
Can you accept a nation willing to enslave sentient beings, citing ignorance as justification?