Can sharks swim without dorsal fins?

Sharks do not and cannot survive with out their dorsal fin.

"If a shark has its fin removed and is consequently returned to the ocean, under almost all circumstances the shark will not survive. Unlike salamanders or sea stars that can regrow limbs that have been cut off, sharks do not possess any regenerative properties that would allow them to regrow their fins."

http://www.nmfs.noaa.gov/stories/2012/08/08_13_12shark_mythbusters.html

"A shark without a dorsal fin is like … well, a dead shark. Sharks whose fins have been lopped off simply don't survive, and yet fishermen relentlessly perform these brutal amputations in order to feed the voracious market for shark-fin soup."

Read more: http://www.utne.com/environment/shark-fin-soup-its-beyond-tasteless-7362.aspx#ixzz2y8mT7G2M