Basically, it means what it says - Toothies (as the Aussies call 'em) won't die off as a species, but the masses tracked by trawlers will be decimated.
I've been out of the seafood importing bidniss for over a year now, but as of early last year it was estimated that something like 60% of the catch was "poached" (not taken via methods used in a properly managed fishery)..a whole lotta quota ignoring going on.
There were, as of last year, some pretty large importers here about to go on the hot seat for knowingly dealing in this sort of black market stuff.
NFP