'Death at Seaworld' is a fascinating and meticulously researched work that centres upon the death of a killer whale trainer at the U.S. theme park in 2010. However the work also takes on the entire history of the captivity of these whales, as well as research undertaken in the wild.
What you get to read may be argued as one-sided as it argues strictly against the captivity of killer whales, but with the evidence presented, there is no other conclusion that could be reached. It does essentially come down to animals performing under extreme duress for the pleasure of humans to bring in dollars.
There is a lot of focus on policy and politics about marine mammals in the U.S., but it never gets bogged down in too much detail, and the people who played a part in these affairs are well-drawn and interesting people in their own right.
An interesting section looks at the plight of Keiko, the star of the 'Free Willy' movie. Keiko was hired from a Mexican animal park to star in the movie. The conditions that he was in were dismal with a very small concrete tank, that was so shallow that his pectoral fins always touched the bottom and had lesions on them. The tale of his journey being an experimental re-release into the wild is a wonderful and enlightening story.
I guess what also sets this work apart from the usual anti-captivity arguments is that it is strictly about killer whales. The author does make an argument for captivity of certain species for educational and conservationist purposes. He is not a die-hard anti-this anti-that person. The argument put forward is strictly about this species and it's conditions and treatment in captivity.
So if you are a bit of a zoological nut check this book out. I highly recommend it.