According to this video only 10% of the fish biomass that was in the ocean during the pre-industrial era is left, due to overfishing.
This seemed overblown to me. And at least one source (admittedly a somewhat activist looking website on the other end of the spectrum) claims, that there have been big problems with the study. It cites three further papers (Walters (2003), Hampton et al. (2005), and Polacheck (2006)), which I have not looked into.
Is the 90% figure true, completely overblown or lies the truth somewhere in between?