For the first time in more than a decade, many Maryland businesses are warning that there won't be anyone to pick the crabs, shuck the oysters or trim the hedges.

Thousands of temporary workers essential to keeping many summer industries humming will not be allowed into the country this year to take their regular jobs. They are being blocked by a cap on the number of foreign seasonal workers.

For the first time since the seasonal worker visa program was established in 1990, the nationwide limit of 66,000 workers was reached this month - early enough to close the door before many seafood processors and landscapers were allowed to apply.

News of the worker shortage has rippled through the Eastern Shore, home to many of the state's seafood processing plants, landscaping businesses and one remaining cannery.

"We're kind of dead in the water without those workers. We can't even reopen," said Harry Phillips, owner of Russell Hall Seafood on Hooper's Island.

With the days when local women picked crabs long gone in most places, the processors say they can't find anyone other than the foreign workers for the jobs. They can't afford to raise wages to attract locals because cheaper imports will undercut their product in the marketplace.

They have already tried to tap into Baltimore's unemployed population. One summer they ran a worker bus between Baltimore and Cambridge. Most days, the only one on it was the driver.

Phillips, a former waterman, bought his 65-year-old seafood business in 1992 - about the time the seafood industry began using the seasonal worker visa, known as the H-2B. The business had been closed for eight years before then, he said, because the previous owner couldn't find anyone to pick the crabs.

Phillips usually hires 50 H-2B workers for his business, and they start around March 30. They are almost all women from Mexico, and most come back year after year.

Bill Seiling, executive director of the Chesapeake Bay Seafood Industries Association, said that has been the case with most of the employers. The workers remain loyal, he said, because they earn good money - up to $200 a day for the fastest crab pickers - and have decent housing provided by the employers for reasonable rents. Workers are paid by the pound of meat they pick, Seiling said, and all pay Social Security, insurance and income tax.

This year, Seiling said, only four of the 25 plants that count on hiring about 1,000 foreign seafood workers will be eligible to get them.

When Congress established the program 15 years ago as an answer to a shortage of seasonal workers in non-agricultural industries, lawmakers imposed several restrictions. First, they set the 66,000-worker cap nationwide to ensure the program wouldn't displace American workers. Second, they said businesses could apply no sooner than 120 days before the workers were needed.

Those restrictions posed no hint of difficulties until last year, when the cap was reached in March. Though processors were able to get their workers, they foresaw problems. Last year was the first the cap had been reached, said Chris Bentley, spokesman for U.S. Citizen and Immigration Services, which is under the Department of Homeland Security.

On Jan. 4, Bentley's office announced the 2005 cap had been met and no more applications would be accepted.

The agency had already accepted more than 100,000 applications, figuring that it would reject about a third of those. An application is no guarantee that a business will get the workers - first, the Department of Labor must certify that the business tried to find local workers for the jobs, then the Department of Homeland Security must make sure the business is eligible under requirements. Finally, the State Department handles the visas.

In addition to the seafood and landscaping businesses, Bentley said, the most common H-2B requesters are industries involved in logging, fish processing, resort management and food service. But he doesn't know why businesses are asking for more H-2B workers.

"We can attest to the fact that the demand is much greater," he said. "What's driving the demand, we don't know."

He added that the department's hands are tied regarding the cap. "There isn't anything now, as the law was written, that can be done," Bentley said.

Three members of Maryland's congressional delegation are trying to do something. Last year, Democratic Sen. Barbara A. Mikulski introduced legislation to raise the cap. That bill never came up for a vote, in part because it became mired in a larger debate about immigration reform. Several senators, among them Republican Sen. Jeff Sessions of Alabama, have said they're worried that these large influxes of labor keep American wages low.