I have cut up well over 150 lbs of elephant tusks and many more Siberian ones. A good sharp bandsaw blade in a wood cutting bandsaw is all you need. I always laid them out first, and cut them in approx 5" lengths starting from the tip as long as it was substantial. If not you might want to start at the hollow end, slowly cutting off the thin stuff until you get to where its thick enough to use. Then lay out the 5 inch lengths (or 4..5 or 5.5 as you see fit) and try to cut it square across. Once you have the sections you can flattten one end and lay out the handle sections and/or solid pieces as you see fit and cut them with the flat end on the bandsaw base to start and once you have cut a couple of the outside curves off you can flatten one and start using that for a base. Hope that is all clear.
oops.........just looked at the picture. One bad thing about walrus is that wierd center stuff. If you want solid, I would cut it in half at the five inch point, if you want scales, cut it in half and then cut the outside off..........the middle stuff is not much good for scales as it will crack FOR SURE.