After a protracted labor dispute that canceled much of the last season, the orchestra is contending with the simultaneous departure of one-third of its players. Ten longtime musicians have retired, and will not be performing when the season opens Sept. 5.

In the short term, many vacancies will be filled by temporary replacements, including some members of the locked-out Minnesota Orchestra.

As part of the agreement reached in April to end the six-month SPCO musicians’ lockout, the full-time complement of musicians fell from 34 to 28, and enhanced retirement plans were offered to senior members. Of 16 eligible members, who needed to be at least 55 years old, 10 accepted buyouts, more than twice the number needed to get to 28 players.

They include bassists Chris Brown and Fred Bretschger, violists Evelina Chao and Tamás Strasser, violinists Thomas Kornacker, Brenda Manuel Mickens and Michal Sobieski, trumpeter Gary Bordner, oboist Thomas Tempel and horn player Paul Straka. Each had played more than 30 seasons with the SPCO.

With the principal clarinet position open and violinist Yoonshin Song having recently departed for the Detroit Symphony, the orchestra has nine seats to fill.

“We knew six or seven might take it, but had no idea how many would” accept the new retirement package, said Bruce Coppock, SPCO president. Potential retirees were offered up to $200,000, based on salary and years employed. Despite fans’ concern over the loss of so many members, subscription renewals are at 85 percent, “above the industry standard of 80 percent,” he said.

Kornacker has been rehired as a special assistant to Coppock, with an immediate focus on auditioning and mentoring new musicians. Auditions for vacancies often take longer than a year.

“The relationship between the SPCO’s musicians and the audience is the most special of any orchestra I’ve been with,” said Kyu-Young Kim, principal second violin, who earlier this year was offered a position with the New York Philharmonic but decided to stay at SPCO in a dual role, becoming the first musician to join management as senior director of artistic planning. “Every new member is embraced by the audience, and we look for musicians who will engage them. It’s built into our DNA as a small group.”

Greg Sandow, a Washington, D.C.-based critic and composer, said the effects of the retirements will be felt for some time.

“If you lose that many people from an orchestra this small, there’s an impact both on morale and how the orchestra sounds,” Sandow said. “It’s not just the skill of the musicians, it’s how they play together. But younger players can add something extraordinary, virtuosity and enthusiasm, once they’re assimilated. And the SPCO are professionals, they know how to do it.”

The SPCO season begins with a series of concerts featuring music of Beethoven, conducted by Edo de Waart.