Slumping summer attendance and rising operating costs will lead to a round of layoffs at the Minnesota Zoo this year, officials confirmed Friday.

The number remains unclear, but plans are expected to be finalized in October.

“We have made every effort to be transparent about our current financial situation,” said spokeswoman Beth Burns, citing discussions at monthly staff meetings. “We’re just at a point where further reductions will require us to look at personnel.”

Expense reductions over the last few quarters, such as trims to the marketing budget and leaving vacant positions open, have not been enough, Burns said.

Layoffs will likely affect all aspects of the staff, including senior levels.

Increased costs relating to salaries, animal feed and energy prices took a toll. A salary freeze was lifted, mandating that the Apple Valley zoo provide raises. That resulted in about $1 million in additional expenses, she said.

Personnel makes up 70 percent of the zoo’s $25 million budget.

Lower attendance during vital summer months also had negative financial consequences. Attendance was down 4.5 percent, Burns said, though the staff still expects more than 1 million zoogoers this year.

The zoo hit record highs of more than 1.3 million earlier in the decade after major new exhibits opened, but may have hit a lull as it works on upcoming additions.

Labor relations groups for zoo employees have been notified of impending cuts and management is working to reach a budget estimate, which will determine the actual number of layoffs.

“I don’t think this is a surprise to anyone,” said Burns, who acts as vice president of external relations.

Burns praised employees for stepping up and asking what they could do to potentially save colleagues. Those who were eligible offered to take occasional unpaid leave days, but it wouldn’t lessen the budgetary strain enough to prevent cuts.

“This isn’t an easy time,” Burns said. “But this is a great zoo, and it will continue to be a great zoo.”