Yes, several species of dolphins and porpoises are in danger of extinction. The Chinese river dolphin, or baiji, is very close to extinction. So is the Gulf of California harbor porpoise. Some of the other species of river dolphins such as the susu and the boutu are also in trouble. However, most species of dolphins are not endangered.
Dolphins live all over the world, from tropical to arctic waters.
How long a dolphin lives depends on the kind of dolphin. We haven't studied them all so it is hard to answer the question. The dolphins in the Indian River Lagoon can be found throughout the length and breadth of the Lagoon. I'm sure that we will find that they prefer certain areas for feeding and other things. It is time to say good-bye.