MIAMI - The number of Cubans attempting to cross the Florida Straits has fallen by more than half, putting 2009 on track to be perhaps the lowest for migration from the communist island in almost a decade.

Experts say it's hard to pinpoint what has caused such a drastic drop but attribute it to combination of factors, with the U.S. economic downturn topping the list. They also point to stepped up U.S. law enforcement against smugglers, eased U.S. restrictions on Cuban-Americans who want to travel to the island and send money to family there and a clampdown by the Cuban government.

“To be honest, there's really no way of telling. This isn't a science,'' said Andy Gomez, a senior fellow at the University of Miami's Institute for Cuban and Cuban-American Studies.

The Miami area's unemployment rate may be one of the main reasons for the drop -- at 11.6 percent, it's nearly double from a year ago, making it harder for Cuban-Americans to pay smugglers to help their families leave the island.

“Most of the people who left were leaving through smuggling operations, and that has stopped because the money here has dried up. The economic crisis has affected that,'' Gomez said. At the same time, he said, on the island ``there's a wait and see attitude'' as to how Cuban President Raul Castro is going to handle the country's economic crisis.

From Oct. 1 through July 31, the U.S. Coast Guard intercepted an average of 72 Cubans a month, compared to 183 a month in the previous fiscal year. The last time the numbers were that low was in 2002, the year after the Sept. 11 attacks.

The U.S. Customs and Border Patrol said there was also a huge drop since last year in the number of Cubans who reached the U.S. by sea, falling from nearly 4,000 annually to about 1,000.

And the number entering through Mexico has plunged, falling to about 5,000 between October and July, compared with almost 9,000 during the same period a year earlier, Border Patrol said.