Either one will do as a gateway. Marine Mammalogy will be covered in both areas.

Veterinarians tend to come from all different types of science majors. If you specifically want to work with marine animals, marine biology would probably be fine. The important thing about your undergraduate career is that you take the courses necessary to make you competitive for veterinary school. You should definitely look at the specific colleges you want to apply to as an undergraduate and make sure that the major that you are interested in will give you the prerequisites required to get into veterinary school (also remember that each veterinary school has its own requirements.) Pay particular attention as well to the required credit hours; for example, marine biology may only require one semester of physics but a particular vet program might want a full year. Of course it's also possible to be an art major and still take the science classes needed to get into veterinary school, but it's just easier to pick a major that has all the requirements necessary for vet school.

I can't think off the top of my head any vet schools that actually have a specialty in marine animals but there may be. I believe Rutgers tends to specialize more in exotics/wildlife, so you might want to look them up. University of Florida also has a vet program and I'd imagine they would have cases dealing with marine animals. Typically if you want to do more "nontraditional" animals (not cat/dog/cow/etc) you would specialize in exotic animals while in veterinary school. Most vet schools start off all students in the same curriculum and then as early as your second year you might start diverging off into what you want to do (i.e. small animals/large animals/exotic.)

As far as jobs entailing a vet working with marine animals, I'd imagine that it would be a pretty competitive job. A zoo veterinarian position in itself is very difficult to get because there are so few of them. With major aquarium/water animal parks they might staff their own veterinarians but smaller aquariums might actually use the local zoo veterinarian (or if there isn't any, the local vet.) I would try to talk to people in these positions to see what their forecast of the future is. When you talk to these people you might also want to ask to volunteer to see what their job is like and get experience working with vets. One of the most important parts of your veterinary application will be experience, whether it be scooping poop at the local vet clinic or actually doing vet technician work. The veterinarian you work for will eventually become the people who will be writing your recommendation letters for you!!!

And if you just want to work with marine animals, like a trainer, I know there are several specialty programs out there that teach you to train animals. One of them is Moorpark College in California (though I'm not sure whether they do marine animals.)

Different universities give different names to similar majors, so it's difficult to answer your question. Of course, the actual classes you'll be taking are more important than the name of the major. If you're serious about working with marine mammals at an advanced level, you'll probably need a DVM (vet school) or PhD. In that case, the most important thing for you is to focus on getting the basic coursework you'll need to get into grad school - calculus, physics, organic chemistry, genetics, and molecular biology (doing well in these classes is especially important for getting into vet school, which is very competitive). You will probably take those classes whether you major in marine biology or zoology. Beyond that, you will likely end up taking more anatomy and physiology for a zoology major (helpful if you want to be a vet) and more ecology and oceanography if you major in marine biology (more helpful if you want to study mammals in the wild). Either way, you should also do yourself a favor and take plenty of English classes - in many ways, becoming a good writer will be the most valuable skill you get in college.

I don't know much about the demand for marine vets. I gather that it's a competitive field, but there are internships available at different places. For example, former student of mine is doing an internship with the US Navy Marine Mammal program in San Diego:
click here

If you end up in the Bay Area for college, you should definitely get in touch with the Marine Mammal Center in Marin. I've volunteered there before and it's a great experience; you might also get a chance to interact with the marine vets who work there.

I think there may also be a Santa Barbara Marine Mammal Center, but I can't find a URL for them.

One final bit of advice - you're only in 10th grade, and it's a long time before you have to really choose a career. It's great that you're already planning out your route to be a marine vet, but if something else catches your interest along the way, don't be afraid to give it a chance. There might be something out there you will end up enjoying more (or have a special talent in) than marine mammals.

I would guess marine biology. Try talking with the staff at the SeaCenter, or contact the Monterrey Aquarium. They have a wonderful programfor rehabilitating marine mammals.

Working with mammals can be a great job. If you want to be a vet, you would go to vet school after your college graduation. To work with them, you might get a degree in biology, zoology (the biology of animals), or marine biology.

This is a good time to start looking at various college programs. The actual wording of your major is less important than the program you attend or what you do when you get there. Ask the college admissions department where their graduates are working now. What percent of their recent graduates have jobs in their field?

Another thing to do now is find people with jobs you'd like to have and see if you can interview them about how they got their jobs and what you should do. Find out what they like and don't like about their job. Are there more jobs or people looking for jobs in their field? Is it likely to change?

Before and during college, try to get work/volunteer experience in your field. And of course it's good to study hard and keep up with current happenings in the field.

That depends on the school you would be going to which department would be better for you. Ultimately I don't think it really matters that much, because you will be able to select courses you want to take to satisfy your major in either case, and courses in marine mammal biology would certainly apply to either.Courses in veterinary medicine are more likely to be in zoology, though, although if you look around, you can probably find a school with courses in veterinary medicine specifically of marine mammals.

Also note: most universities don't have departments of zoo logy anymore. They have biology departments, ofwhich biology is usually divided into the ecology-evolution branch and the molecular-genetic branch, sometimes with an organisms branch as well.You're looking at the organisms subjects, which will usually be in with the ecology section if they don't have their own department. At UCSB, the department is E.E.M.B., for Evolution, Ecology, and Marine Biology.I would tend to expect that some of the schools in the CSU system would be better if you wanted to go into veterinary medicine (the University of California is a research-oriented operation, more exploratory and theoretical than practical, which the CSUs are).