If that is a photograph, it is not New York harbor. The US banned importation of slaves in 1808 (read the Constitution) and photography was not invented until the 1840s. While illegal slave smuggling occurred quite frequently after 1808, New York harbor was hardly the place they would make port since there was no slave market north of Baltimore. And the slavers were not dumb enough to put into a major port like Baltimore and risk losing their ship and technically, their lives. If that is a slave ship in the photograph, it must be in a more remote spot like Sullivan Island, SC were the vast majority of contraband slaves were brought in after the slave trade was outlawed.
BTW. Slavery after 1808 was considered piracy with automatic sizure of the ship (like drug running today) and the death sentance for the Captain! The US Navy captured many slave ships over the years and in all but one instance, the Captain was not hung. The one exception was in the early 1860s when a American flagged ship was caught off the coast of Africa. Abraham Lincoln had the Captain hung!
BTW. I can only assume you are retreating to the standard fall back position that "The Yankees Were Worse --- They Made the Poor Southerners Buy All Those Slaves". I can only ask, even if that's true, what the hell does that have to do with the Civil War and Abraham Lincoln?