de-parasiting mackerel for sushi We've bought some fresh sushi-grade mackerel, and would like to make saba sushi from it. We were told that we should treat it with vinegar to kill any parasites. 

Some online recipes I've seen recommend a two step process of first salting for 30-40 mins, then marinating in vinegar for 30-40 mins. Others extend the salt step to 3 hours. 

Is the salting necessary for de-parasiting? I ask because the fish store guys, who are usually very knowledgeable, didn't mention it. If so, is 3-4 hours really necessary, or is 30-40 minutes more like it? 

Clearly I'm eager to eat this fish, but I'd like to play it safe :)
The FDA recommends below, which is how every restuarant I have ever heard of does it as well.

A recent survey of U.S. gastroenterologists has confirmed that seafood-borne parasitic infections occur in the U.S. with sufficient frequency to make preventive controls necessary during the processing of parasite-containing species of fish that are intended for raw consumption...[]..Freezing and storing at -4°F (-20°C) or below for 7 days (total time), or freezing at -31°F (-35°C) or below until solid and storing at -31°F (-35°C) or below for 15 hours, or freezing at -31°F (-35°C) or below until solid and storing at -4°F (-20°C) or below for 24 hours is sufficient to kill parasites. FDA's Food Code recommends these freezing conditions to retailers who provide fish intended for raw consumpution