Shortages of employees with certain crucial skills and the pending loss of many experienced workers to retirement remain major management challenges for the government, although progress has been made in some areas, according to a report issued Thursday.

What the Government Accountability Office has called “strategic human capital management” remains on its high-risk list, where it has been in every such biennial report since 2001.

“Addressing complex challenges such as disaster response, national and homeland security, and economic stability requires a high-quality federal workforce able to work seamlessly with other agencies, levels of government, and across sectors,” the report said.

“However, current budget and long-term fiscal pressures, coupled with a potential wave of employee retirements that could produce gaps in leadership and institutional knowledge, threaten the government’s capacity to effectively address these and many other evolving, national issues,” it added.

The GAO said that about 30 percent of federal employees as of 2011 will be eligible to retire by 2016, the long-predicted “retirement wave” of the relatively older and longer-serving workforce.

According to a White House budget document, 22 percent of federal employees are 55 or older, compared with 18 percent in the private sector. Office of Personnel Management data show that almost three in 10 federal workers have 20 or more years of experience with the government.

The GAO said the potential loss of expertise due to retirements is especially worrisome for some agencies, including the Department of Housing and Urban Development and the Small Business Administration; in some occupations, such as air- traffic control; and at more senior levels. Nearly three in five senior executives will be eligible for retirement in three years, it said.

Agencies, meanwhile, continue to suffer from “skills gaps” in certain crucial occupations, the GAO said.

These include cybersecurity, at a time when “threats to federal information technology infrastructure and systems continue to grow in number and sophistication,” and management of contracts, which “have become more expensive and increasingly complex,” the report said.

Other areas of concern include aviation safety, oversight of oil and gas activities, and various defense-related occupations.

The GAO added, however, that the OPM, individual agencies and Congress have focused on identifying and addressing shortages of high-priority skills. In addition, the OPM “has taken steps to improve the federal hiring process, with the aim of making it easier for people to apply for a federal job and strengthen the ability of agencies to compete with the private sector for filling entry-level positions.”