The improving U.S. economy brings with it a growing demand for workers with highly specialized skills -- skills that many companies are finding to be in short supply.

Adam Berry, Getty Images

"Today, companies are looking for specialists," said Rich Singer, senior vice president director of permanent placement at Robert Half International, a recruiting and placement firm.

Singer said finding people to fill positions in accounting and information technology (IT) is especially challenging for companies.

In New Jersey, workers in high demand include those who specialize in pharmaceuticals, biotech, real estate, consumer products and construction.

Quite simply, there just aren't enough workers to fill these positions.

Singer said the national jobless rate for IT professionals right now is less than one percent, and in many accounting specialties, it is less than three percent. The jobless rates for these two fields is lower than the overall national unemployment rate of 5.6 percent.

Over the next 10 years, the U.S. Chamber of Commerce projects double-digit growth for accounting professionals. "There's just not enough of them to go around," Singer said.

Companies that specialize in accounting are having trouble finding public auditors and financial analysts. And as companies seek out the highly-skilled, they are wading through the resumes of many lesser qualified applicants.

"There's a lot of marginal people who are looking for work," Singer said. "But the good candidates have a shelf life (on the market) of several weeks to three or four weeks, if that. And they're getting multiple offers."

Additionally, Singer said, it is difficult to find people "who are really motivated, who have a really good career path, who are willing to work hard."

For some firms, recruiting is only half of the staffing battle. Retention of their star employees is the other half.

"If you (employers) don't take care of your employee - the compensation level and work-life balance - there is a good chance in the next year or so you are going to lose that person," Singer said.

In order to retain key employees, many employers are being proactive by giving highly-valued employees raises, bonuses and a more flexible work-life balance, which might include working from home.

Those in demand can often write their own ticket, Singer said. "There's tremendous competition for employees."

According to a survey by Robert Half International, in 2014 only about nine percent of chief financial officers (CFO) said they were willing to negotiate starting pay with candidates. That has now jumped to 68 percent.