The cuts follow 200 redundancies made earlier this year, which were planned before Platinum Equity took control of the paper in May.
Platinum Equity earlier this week emerged as a bidder for The Boston Globe.
The job cuts at the the California newspaper follow 70 announced yesterday at The Journal News near New York.
AP reports that The San Diego Union-Tribune plans to focus more on local community news and launching what it has dubbed a "micro-zoning" initiative for small businesses to advertise at lower rates.
Ed Moss, president and publisher of the Union-Tribune, said: "These are just a few things we have in mind to help us strengthen our relationship with the San Diego community and with our advertisers and readers. We are the region's leading local media company, and we are passionate about our goal to be a strong company for many years to come."
He added: "These initiatives are producing results, as revenue has increased since these new strategies were put in place."
The local community news focus includes initiatives such as the Neighborhood Express Project, which launched last month to bring hyper-local coverage to targeted communities in San Diego.
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