Is it true that fresh sushi is not delivered to Toronto restaurants on the weekend?
Sushi is never delivered to restaurants as far as I know... (unless if you call those mall teriyaki stands restaurants)
I think you are asking if fresh raw fish is delivered to restaurants for them to make sushi, right? I believe a lot of them use frozen raw fish for sushi anyway, so the point is moot. But maybe someone would know how top end places like Kaji, Omi etc get their fish.
As a general rule, like any other product, it's safe to assume that most fish deliveries happen on weekdays. That means if you order fish on Saturday or Sunday, it was probably delivered on Friday. Even ordering fish on a Monday is somewhat risky, because if certain deliveries have not yet arrived you may still be eating fish delivered the previous Friday. This doesn't mean the fish is automatically rancid or bad, of course, but it's worth keeping in mind when you are ordering. Anthony Bordain opened my eyes to this one in his first book, and though he was talking about NYC, I highly doubt Toronto is any better or different.
And like Teep says, even though there was a lot of hoopla in Ontario a few years ago when the government tried to pass a law mandating that all sushi fish be frozen before being served, the fact is that a lot of sushi chefs seem to quietly admit that some of the fish they serve has in fact been frozen, and they prefer it that way. Many people have noticed that Toronto is not located alongside an ocean, and Lake Ontario fish is not very suitable for raw consumption.
This means that the fish we eat has been flown, at minimum, a few thousand kilometres from the East Coast of Canada, and when special sushi delicacies are involved, it's probably been flown many thousand kilometres from the California coast or even the seas near Japan. I believe some of the super high-end sushi joints are more likely to order special deliveries straight from Japan, which accounts for some of their very high prices. But even that must take a few days in transit, unless they own their own personal Concord.
None of this is really a shocking secret. I guess we should be thankful that we live in a modern age of refridgeration and air transport that lets those of us who live in the frozen wasteland of Canada enjoy things like raw fish and fresh fruits in March, even if the quality is not always quite as superb as you might find in a warmer clime.