PORTLAND – Maine’s work force is showing its age with a population that continues to get older and a lack of younger workers to fill the void.

The number of Maine workers ages 45-54 grew by 35 percent in the decade ending in 2005, according to the Maine Department of Labor. At the same time, the number of workers between 55-64 grew by 72 percent, and those 65 and older increased 51 percent.

Meanwhile, the number of employees ages 25-34 fell by 17 percent from 1996-2005, and 35-44 fell by almost 6 percent. The number of workers ages 17-24 grew by 8 percent.

The work force will only get grayer in the years ahead. By 2030, about 22 percent of Mainers will be 65 or older, up from 14 percent in 2000.

John Dorrer, director of labor market information services for the Maine Department of Labor, said there aren’t a lot of understudies around to step in when jobs need to be filled.

“We haven’t really brought a lot of people along who can step in and perform,” Dorrer said. “That leaves us a little more vulnerable. When people do retire, who do you turn to?”

Every part of the country will have to grapple with the problems posed by an aging work force as the huge baby boom population ages and approaches retirement.

But Maine will feel the problem more acutely because it is the country’s demographically oldest state and has a slow-growing population.

It is also losing much of its younger generation to other parts of the country while attracting older residents who see Maine as a good place to retire.

Other states, particularly in the South and West, are growing rapidly, have higher birthrates than Maine and are attracting a lot of immigrants.

Economist Charles Colgan said the aging labor force makes for an uncertain future.

“I don’t think anybody has a good sense of how this is all going to work,” said Colgan, a professor at the University of Southern Maine’s Muskie School for Public Service. “This is all unknown territory.”

There are a few trends that are counteracting the problems posed by an aging work force, however.

More baby boomers are putting off retirement or are switching to part-time work either by choice or financial necessity.

“Many baby boomers, with 401(k)s that are not all that well endowed and Social Security not meeting their needs, will have to continue to work,” Dorrer said.

But businesses and the state still need to plan ahead because the leading edge of the baby boom generation turned 60 last year – meaning large numbers of workers will be looking toward retirement in the years ahead.

“It’s going to force us to be creative and innovative,” Dorrer said. “We have to be more imaginative, more creative and jump on this faster.”