Courts have allowed the Navy to continue to do sonar testing off the California coast, has it been proven that these tests harm marine life?

I think they (environmentalists) believe the sonar effects their ability to navigate and that this use of sonar testing by the Navy is the reason for the noticeable increase of sea mammals getting lost in harbors and beaching themselves.

Affects their ability to navigate, kind of like staring directly at the sun all day would affect a human’s ability to walk around (being painfully blinded and all).