Arlington County, stung by the expected loss of 17,000 jobs and concerned about the impending opening of the Silver Line in nearby Tysons Corner, will focus this year on luring high-tech start-ups, university researchers and corporations working with federal science agencies.

Newly elected board chairman Jay Fisette said Wednesday that Arlington will use a new $700,000 public-private partnership fund to help tech start-ups find a home within the small, urbanized county.

Fisette spoke Wednesday at Arlington’s annual New Year’s Day organizational meeting.

The board and staff should “lay the groundwork for Arlington to become a hub for the innovation economy — the 21st-century economy of flexible, creative enterprises and high-tech services,” he said.

Fisette called for the county to engage in “aggressive business development” by marketing Arlington nationally and internationally. He also wants the county to update its plans that require or encourage first-floor retail in mid-rise and high-rise buildings and wants to improve its relationship with businesses.

Development barely paused in Arlington throughout the recession and recovery of the past six years, but the commercial vacancy rate for the region is now 20 percent, its highest in more than 20 years. That is partially because of the U.S. government’s recent base realignment process, which is expected to cost the county 17,000 jobs over a decade by scattering defense agencies that had been concentrated near the Pentagon in Arlington.

Some residents, including unsuccessful candidates for local office, have argued in the past few years that the County Board is too respectful of developers and too eager to trade housing density in exchange for cash or promises to add a few low-cost apartments in upscale projects.

But Fisette (D), who won reelection to his fifth term in November and who has served as the board’s chairman three previous times, said the county needs to continue to make “strategic investments in infrastructure — particularly transportation and technology” to improve the county’s economic health.

He singled out the Columbia Pike streetcar project, as did three of the four other members of the all-Democratic board, as important to the growth of the county.

Board member and streetcar opponent Libby Garvey, however, continued to voice her opposition to the project: “My alarm about this project only grows. I hope we never build a streetcar.” She also spoke out against proposals for the Artisphere and the Long Bridge aquatics center.

Fisette pledged to work with the School Board, which is elected separately but which must go to the County Board for its budget. Only 13 percent of Arlington adults have children in public schools, but they routinely agree to bond issues for expansion of the schools. Over the next five years, Fisette said, enrollment is projected to increase 18 percent. That growth will require more construction, he said, and he called for regular meetings between county and schools staff.

Affordable housing, another controversial issue, also will demand attention in 2014, Fisette said. Since 2000, the county has lost about 12,000 units of affordable housing for low- to middle-income people.

Despite creating more than 6,600 units of affordable housing, Arlington rents continue to rise beyond the reach of many working residents. Fisette pledged to follow through on plans to find county land where lower-cost housing could be built.

Fisette, who last year urged county residents to stop buying plastic water bottles because of the cost to the environment, will ask the rest of the board this year to adopt a 25-year strategy for the county to create no waste. Recycling in Arlington is already at 51 percent. He also touted a county project that is laying 38 miles of fiber-optic cable underground that will link every county and school building and every traffic signal and public safety tower.