“I don’t understand your question.”
I’ll ask it in another way. If Northern economic subjugation caused the decline of the Charleston port, why didn’t other Southern ports like New Orleans decline too?
Much of it's shipping was coastal packets bound for New York where the cargo was offloaded onto faster ocean going vessels.
It was way bigger than Charleston. That being said, with a 35-45% increase in profits for trade ships under the CSA, had the Union blockade not prevented trade, the vast majority of trade would have moved to Southern ports, and New Orleans would have seen a commensurate increase in trade due to it's greater importance in the overall trade system.
The Union was going to get it's trade eaten alive by the South but for Northern warships stopping that from happening.
Like I said, the Civil War was about money, not slavery. The Corwin amendment proves the North would continue to tolerate slavery, but they would never tolerate the cessation of their money streams.