There are not any colleges that offer majors in marine mammal training, and if you ask the trainers, there are about as many different majors as there are trainers! Some of the most popular majors are marine biology, psychology, and biology. Other majors that are relevant to the field include ecology, animal science, oceanography, environmental science, and ocean science. Any type of science will help in the understanding of the habitat of where animals live, as well as the dangers that they face, while psychology and behavior classes teach learning theory and how that applies to the use of behavior modification in animals. The most important thing is the experience that you gain while in school through volunteering and and internships. This experience will help fill in the gaps that your classes leave out - this is a field where you are always learning! Any and all animal experience will help you in the field. It is important to remember that it is a very competitive field as well, so any experience that you have will help you in your job search and with networking.