The unfortunate thing is that no matter whether something is illegal or not, it can still be a victim of bycatch when fishing for legal species, and bycatch mortality is quite high. Bycatch is actually higher than actual catch by weight for some fisheries+methods.[1] It's not just what you eat, but where it came from.

[1] http://www.fao.org/docrep/003/t4890e/t4890e03.htm

Edit: A couple of extra spaces removed