Animal activists found two more pelicans near Summerland and Cudjoe Keys that had their pouches slit open.
The pelicans were brought to the South Dade Animal Hospital to undergo surgery on Monday.
"When they attempt to net the fish with their pouch, everything just goes out the bottom of it, so they can't contain the fish," said Dr. Don Harris.
"We don't know who did it, why, and how," said Maya Totman, director of the Florida Keys Wildlife Rescue. "We don't know."
Totman said five other pelicans have died.
"I have no words, I'm just heartbroken over it," she said.
The two pelicans should be okay after six weeks of rehabilitation, said Harris.
"Whoever did this didn't just want to kill the pelicans, they wanted to punish them," he said. "They wanted them to die of starvation."
The Florida Fish and Wildlife Conservation Commission reports 10 pelicans have had their pouches slashed.
Anyone with information in these cases is asked to call 888-404-3922.