The roars of the mighty lions were silenced yesterday when the two remaining African lions at the Honolulu Zoo were euthanized.

The lions, Ethel Louise and Samantha, were 22-year-old sisters and had suffered from multiple health problems associated with their age, the city said. The lions were main exhibit attractions at the zoo for more than 11 years.

The zoo plans to obtain other lions, Honolulu Zoo director Stephen Walker said.

Walker said the decision to put the animals down was difficult, but that no one on the zoo staff wanted to see the sisters suffer. Ethel and Samantha were taken off the exhibit a couple of weeks ago because of their condition, he said.

"It is tough," Walker said. "There were a lot of people who had worked with these animals for a long time and they become part of your family. But there was pretty much universal agreement from the animal keeper staff that at this point that was the correct decision to make."

He said lions in the wild that are faced with the same health problems would not have lived this long.

"They were almost 23, which is very respectable for lions," Walker said. "There's not a magic number that they always live to, but any lion over 20 years old is considered extremely old by lion standards."

Ethel and Samantha were born on April 3, 1986, at the Wild Wilderness Zoo in Gentry, Ark. The Honolulu Zoo purchased the lions from the Pittsburgh Zoo and they arrived in Honolulu on July 28, 1997.

The two had shared the exhibit with male lion Apollo until he was euthanized in August 2007. Apollo, who suffered from kidney failure and arthritis, was 21.

Walker said the zoo plans to bring in a male lion at the end of next month. He said the lion will be on loan from the San Diego Wild Animal Park.

He said the zoo also is working to obtain female lions.

In the meantime, the zoo staff will cope with the loss of Ethel and Samantha.

"When we made the final decision, we let the keepers that have worked with those animals know so that they could come in and say their goodbyes to the two lionesses this morning," Walker said.

The wild African lion population has decreased drastically over the past 20 years. Officials estimate that there are 25,000 left in the wild, compared with 200,000 in the early 1980s.

For information on what the Honolulu Zoo and the Lion Species Survival Plan are doing to restore the lion population, visit www.aza.org.