If that chef is japanese,he may mean the "Ciguatera Fish Poisoning "that is commonly known in Japan.all sushi chef must know this.
http://www.holistichealthtopics.com/HMG/ciguatera.html
I know a few of my friends talk about it and I've also heard of some lawsuits toward sushi restaurant in japan for people got sick because of that bacteria.
but I myself had never had problem with fish that I ate in raw all my life.
so i will keep eating.
if LJ YTL have problem with bacteria,we all know about that for long time already and most of all commercial fisherman should know.
I think we should not worry about.
btw,WASABI kills bacteria(one German scientist found out).
Gari(pickled ginger)also kills bacteria.
it make all sense that we eat sushi or sashimi with those stuff.
mizu