PORTLAND — Catherine McAuley High School will no longer be a Catholic school or run by the Sisters of Mercy, effective July 1, 2016, the school announced Wednesday.

The school announced it will become an independent, private, college-prep school.

In a joint statement Wednesday, McAuley board Chairwoman Heidi Osborn and Sister Jacqueline Marie Kieslich, president of the Northeast Community of the Sisters of Mercy of Rhode Island, said to best realize the school’s mission, institutions must evolve with the times. McAuley and the Sisters of Mercy reached the decision that the school can best continue to serve students by ending the historical affiliation.

A decline in the birth rate, a tough economy and fewer Catholics attending services  means enrollment in Maine Catholic schools has fallen sharply in the last decade  with many Catholic schools closing or merging. As enrollments have declined, tuition costs have spiked.

The other Catholic high schools in Maine are Saint Dominic Academy in Auburn and Cheverus in Portland.

“This is surprising to me,” Don Fournier, president of Saint Dominic Academy, said Wednesday. “I’m sorry we’re going to lose another Catholic school.” For high schools, “now it’s us and Cheverus. I’m sad whenever that happens. We’ll look to shore up our programs and get bigger and better.”

Fournier said St. Dom’s generally doesn’t draw students from the Portland area. He doesn’t think McAuley’s decision will mean many Portland area students will transfer to St. Dom’s.

According to McCauley’s statement, the school will continue to be for girls and remain on its historic Stevens Avenue campus, not far from the St. Brigid Catholic elementary school.

Maine Catholic Bishop Robert Deeley said he’s saddened “to learn of the change in the sponsorship status of Catherine McAuley High School. We regret the loss of a Catholic school in our diocese,” he said in a statement.

Since the school was founded in 1969, “the Sisters of Mercy have welcomed thousands of girls into their classrooms, providing each student with an outstanding education and an understanding of how best to serve God and one another,” the statement said.

Deeley said the church owes the nuns “our sincere gratitude for their many contributions, especially to education and health care.”

For parents who want their high school children to continue with a Catholic education, Deeley said the diocese offers Saint Dominic Academy in Auburn and the Jesuit Fathers offer Cheverus High School in Portland.

“Both schools have long histories of promoting academic excellence and service in the context of a faith-based education, and would welcome your families warmly into their school communities,” he said.