Green’s Dictionary of Slang

(US) a newly-arrived Puerto Rican immigrant.

1953		Kramer & Karr Teen-Age Gangs 93: Two transports converted to passenger ships plied regularly between New York and Puerto Rico. These were the Marine Tiger and the Marine Shark. The first carried so many immigrants that the slang term for a new arrival became Marine Tiger.
1959		‘Ed McBain’ Killer’s Wedge (1981) 42: Look, you little slut, cut the Marine tiger bit, will you? We know you didn’t just get off the boat.