Many of those scars depict bite marks of other male dolphins fighting for females or females raped. Failed killer whale attacks, deep sea shark bites and cyamid parasite "cities" can be seen also.

Thanks, all this time I thought they were obvious propeller scars.

Are you sure those are propeller scars? They look too shallow and close together. Propeller scars I've seen have looked more like deep cuts more widely spaced out. Propellers are moving with incredible force. I imagine they cause quite a bit of tissue damage upon contact, and it seems unlikely that you'd be able to see such fine detail.

Example of true propeller scars: https://www.tampabay.com/news/environment/wildlife/scars-of-...

This parallel lines in your photos are dolphin teeth's marks @suzzer99. Most are just scratches in the skin.