The attempt to blockade Southern ports and cause the Confederacy great economic harm was based on the once discarded Winfield Scott plan called the Anaconda Plan. The idea was sound enough, however, there were logistical problems involved with a really effective blockade. There were simply too many ports of entry, night time privateers escaped scrutiny and there was not enough Union warships to handle the project. It is also important to remember that ship to ship communications in 1861 were primitive. And, ship to shore communications also lacked the technology to communicate. Also, the threat of Confederate river and sea mines caused any number of problems To deprive the Confederacy of the many imports it needed, both for troops and civilians.
It is argued that Lincoln was effectively acknowledging the validity of the new nation by 'blockading' its ports, instead of simply announcing the closure of certain ports it considered its own .d. He wanted to stop the South from bringing in any more slaves.
