The Alcatraz history page sketches out 14 escape attempts, but none that mentioned a shark-bitten shirt. In fact, it states that ‘one of the many myths about Alcatraz is that it was impossible to survive a swim from the island to the mainland because of sharks. In fact, there are no “man-eating” sharks in San Francisco Bay, only small bottom-feeding sharks. The main obstacles were the cold temperatures (averaging 50-55 degrees Fahrenheit), the strong currents, and the distance to shore (at least 1-1/4 miles).’
