A letter from the Michigan Corrections Organization says in June, there were 28 prison fights, 20 incidents of prisoners assaulted by other prisoners and a dozen assaults on corrections officers.
Union president Byron Osborn says there are hundreds of staff vacancies at U-P prisons, creating an unsafe environment.
"So those things are obviously very dangerous because that's less staff to respond to incidents and less staff to run the normal operations."
A bill that would have added officers to the state police hybrid pension plan is stalled. The union says it would help with recruitment.
The bill was passed last year but not sent to the governor's desk before the end of the legislative session.
State Senate Democrats are suing the House GOP in hopes of getting the bills to the Governor.