SALEM, Ore. (AP) — Oregon Health & Science University paid a fine of nearly $12,000 following the deaths of five monkeys and the escape of nine others from the Oregon National Primate Research Center in 2009.

University officials said Tuesday that they agreed to a settlement with the U.S. Department of Agriculture and paid the fine on four violations earlier this year. A group opposed to animal testing called the fine "paltry."

In a letter dated May 8 to OHSU's chief lawyer, USDA investigators said the university could settle the cases and avoid a fine up to $40,000 and other sanctions.

Two monkeys died as a result of dehydration when a new water system didn't work at the research center in Hillsboro. One was killed when it was given an excessive dose of a sedative being studied, and two others died when a miscommunication resulted in them being given a toxic substance not intended for living animals.

University officials said they've taken steps to ensure the mistakes aren't repeated, including retraining staff and requiring daily checks of water lines.

"These incidents are unfortunate and the animal losses were felt deeply by our staff," Nancy Haigwood, director of the primate research center, said in a statement. "The personal impacts of these incidents on our veterinarians, animal caregivers and scientists far outweigh any fine."

Researchers seek a balance between advancing human and animal health while ensuring the wellbeing of animals being studied, she said.

The $11,679 fine includes a sanction for the 2009 escape of nine monkeys. The macaques, which were part of a breeding colony and not involved in health research, got free when a worker forgot to latch the door to an outdoor cage. Four were captured immediately, but the last wasn't found until two days later.

OHSU officials they've built a new perimeter fence that's harder for monkeys to climb and trimmed nearby vegetation. The center also improved the fencing in front of the doors to the monkey cages and created a specialized team of employees with expertise in capturing animals in case of any future escape, though there hasn't been one, officials said.

Stop Animal Exploitation Now, a group opposed to animal testing, said the fine should have been much higher.

"The USDA is literally allowing OHSU to get away with murder" Michael Budkie, the group's director, said in a statement.

Officials at People for the Ethical Treatment of Animals, which also opposes animal testing, said they were pleased primate center was being punished.

Since the four 2009 violations, OHSU has reported 11 other incidents to federal regulators, including the deaths of five monkeys. One died in 2010 from a caffeine overdose, another the next year after fighting with other monkeys. This year, one monkey died after running into a wall and two died while being transferred with other animals through a tunnel for health checks.

Officials are still investigating why the monkeys died in the tunnel, OHSU spokesman Jim Newman said.

In other incidents, researchers reported violations including taking unnecessary blood samples from a monkey, castrating two rats using procedures that weren't preapproved and performing surgery not in the study protocol. In all those cases, the animals were treated and are OK, Newman said.