Realistically, a college degree is very important. The marine mammal field is constantly growing and changing. It is important to do as much research as you can. Take classes that will advance your public speaking skills and knowledge of the animals and environment in which you will be working. If you are going to be working with animals, the abilities to think clearly, quickly and with common sense are unspeakably important.
Physical fitness is also a definite prerequisite.
You will probably spend a great deal of time in or near an aquatic environment making strong swimming skills essential. Fortunately, there are a number of ways to become involved in the marine animal community. It is important to visit facilities and learn their operations, resources and procedures. This may give you a better idea of the organizations you would like to work with. On a more national level, you should consider joining at least one of several professional organizations .