Here Duffy is not really trying to prove herself an animal lover. Her sole purpose is to protest against human cruelty towards animals and nature at large. That is why she presents the dolphin who are confined to a pool with restricted movements to depict how we humans are treating other animals badly for our own entertainment or monetary purpose. She tries to make the readers feel bad for the dolphins and make us understand that this kind of actions from man may eventually lead to a destruction of nature and its ecosystem. That isn’t going to be good for us at all. In short, the poet just wants us to feel for the creatures and let them live in their natural habitat.