All three of the big caspian caviars will be covered in CITES appendix, and will not be available in the USA. It's no big loss, california produces some very nice white sturgeon that rivals the imports, if it doesnt blow them out of the water.
about the actual conservation of it, there are a lot of very poor people who subsist by selling sturgeon/sturgeon by products in eastern europe, and they will continue to fish the sturgeons to extinction whether we stop eating the caviar or not. It's unfortunate, but its life. No amount of banning can save the sturgeons, because demand is high and supply is dwindling. the legality of exporting it is hardly the first thing that the fishermen are concerned about.