Douglas Hanks / The Miami Herald

MIAMI — As an unemployed yoga instructor, Cynthia Cutler was excited to get an email response so quickly from a recruiter at Canyon Ranch at Sea, which runs spas and fitness programs for posh cruise ships sailing out of South Florida.

“I was looking to leave Miami,” said Cutler, 57 and a Key Biscayne, Fla., resident. “I thought a job on a cruise ship would be perfect.”

Then came the question that seemed to scuttle Cutler’s chance for a seafaring career change: Which country issued your passport?

“Oh my goodness!!!!” Thalia Shaer, Canyon Ranch’s international recruitment coordinator, wrote back in the Sept. 17 exchange, according to emails Cutler provided The Miami Herald. “Cynthia, the Sea Division is not allowed to accept American staff due to tax laws in the U.S.”

A Canyon Ranch spokeswoman later described Shaer’s email as an error and said Canyon Ranch’s cruise line division has no policy against hiring U.S. residents for its spas on Regent’s Seven Seas Navigator, Oceania’s Marina and other ships that contract with Canyon Ranch and have sailed out of U.S. ports.

“We hire the best person for the job, no matter what their nationality is,” said Sheryl Press, spokeswoman for Canyon Ranch, which is headquartered in Tucson, Ariz.

Still, the numbers suggest some challenge in matching U.S. residents with Canyon Ranch jobs at sea. Press said that of the 115 spa employees in its cruise ship arm, only four are U.S. citizens.

“Our positions don’t turn over very often,” Press said. “People obviously enjoy what they’re doing, and not that many openings come up.”

Cutler’s ongoing hunt for a spa job at sea — Canyon Ranch has since written back to set up an interview in Miami for November — touches on a well-known characteristic of the cruise industry. While a major employer shoreside through Carnival and Royal Caribbean’s world headquarters, cruise lines recruit the bulk of their ship workers from abroad.

Figures are hard to come by. Carnival, the world’s largest cruise line, said it does not release nationality breakdowns for its roughly 77,000 shipboard employees on the 99 ships it operates around the world.

In a statement, Carnival spokeswoman Jennifer de la Cruz said the United States holds a spot in the top 10 source countries for Carnival shipboard employees. The United States has the world’s third-largest population.

“Carnival Cruise Lines has numerous Americans working aboard our ships, and we routinely hire American crew members,” de la Cruz wrote. “The cruise industry is very international in nature, and we typically have crew from more than 100 different countries employed on our vessels.”

David Peikin, a spokesman for the Cruise Lines International Association, said the trade group was unaware of any U.S. tax law that would discourage cruise ships from hiring Americans. “In fact, many U.S. citizens work on cruise ships that are both U.S.-flagged and foreign-flagged,” he said in an email.

He also described cruise ships as offering jobs in demand around the world. “Jobs in the cruise industry are highly desirable and highly sought after,” he continued. “In addition to their salary, crewmembers typically receive free medical care, room and board, meals and many other benefits that are often unavailable in their home countries.”

Critics of the cruise industry see the use of foreign workers as another way of boosting profits — similar to how Carnival and other cruise ship companies avoid U.S. corporate taxes by incorporating in foreign countries. (Local employees and facilities of cruise ship companies are subject to all local, state and federal taxes.)

“The benefit of hiring a non-U.S. worker is, of course, you can pay them what you want to pay them,” said Jim Walker, a South Miami lawyer who represents passengers and cruise ship employees suing cruise lines over injuries and shipboard incidents. He also runs the website Cruise Walker pointed to a 2009 document that shows Royal Caribbean offering one of his clients from Turkey a waiter’s job aboard a ship with a monthly wage of $50, plus another $1,000 a month in guaranteed tips.

The latest Royal Caribbean annual report notes 80 percent of its 54,000 shipboard employees are covered by collective bargaining agreements negotiated by union leaders.

“These labor agreements provide reasonable pay and benefits to employees, including guaranteed monthly pay for tip-earning employees,” Royal Caribbean said in a recent statement. “This means that crew members are protected with a significant guaranteed pay rate in the event lower tips are collected in a certain month. Most tip-earning employees receive tips that are significantly higher than the minimum guarantee each month.”

Of course, cruise lines aren’t alone in hiring abroad. Hotels, farms, construction and landscaping crews regularly lean on international recruiters to fill low-wage, grueling jobs that are hard to staff with domestic workers. The combination of low pay and long hours that comes with many cruise ship jobs makes them less attractive in the United States, where entry-level retail jobs can pay close to $10 an hour.