There's a balance to be struck with UV unwrapping. Don't worry so much about minimization of seams that it affects your ability to texture the asset nicely, for example. Sometimes eating a few seams in order to get a nice flat unwrap in key areas is worth it when you consider the larger picture.
Okay, here's some tips. Also you had some weird geo (doubled verts) on your mesh that I cleaned up. Also I deleted 3 of the 4 fins, you can just mirror them back (Once you've finished the UV's—would make sense to have them overlapped / share the same texture to save space). You might also want to bookmark this for further…
I'd like to see some examples of these unwraps. It's usually a few hours for me on each piece because I play tetris for awhile trying to get an optimal use of UV space happening.