SAN FRANCISCO, Calif. -- The San Francisco Zoo will remain a partial rescue zoo and not have to undergo an overhaul demanded by animal rights activists concerned about animal welfare issues at the aging facility, city supervisors decided Tuesday.

The San Francisco Board of Supervisors voted down by a 7-4 margin an amended version of legislation that would have only created an advisory committee to the board on animal welfare issues at the zoo.

The legislation's sponsor, Supervisor Chris Daly, said the original proposal represented a "righteous" vision that "puts the welfare of the animals first," but offered to remove the "teethy language" that would have made the zoo's primary mission the housing of wildlife, domestic and exotic animals rescued from inhumane treatment.

Zoo officials had argued such a transformation would threaten the zoo's current education, conservation and breeding programs, as well as future fundraising efforts.

Critics of the zoo, including the animal rights group In Defense of Animals, have claimed many of the zoo's facilities and enclosure are outdated and inadequate for the proper care of its animals.

They cited the deaths of elephants and other animals at the zoo in recent years; aberrant behavior among other animals seen pacing in their enclosures or gnawing at the sides of buildings; lack of shelter for animals in some exhibits; and December's tiger escape during which a zoo visitor was mauled to death and the tiger was subsequently killed.

Daly warned that the city still faces significant potential liability for the Christmas Day attack, during which 17-year-old Carlos Sousa Jr., of San Jose, was killed, and two of his friends, brothers Amritpal and Kulbir Dhaliwal, also of San Jose, were severely injured.

Lawyers for their families have threatened lawsuits against the city.

The zoo is owned by the city and managed by the nonprofit San Francisco Zoological Society. The zoo's current lease with the city expires in 2013.

A report issued Friday by the city's Office of the Legislative Analyst, though acknowledging the study had not been conducted by zoo experts, concluded the zoo was for the most part in compliance with national and international animal welfare and conservation standards, but needed to make faster progress on modernizing its older exhibits.

"Some of the Zoo's animals may be suffering physically and mentally because their enclosures do not meet contemporary zoo standards," the report stated.

Zoo officials have pledged to continue work upgrading nearly half of the zoo's exhibits, some of which are decades old.

Tanya Peterson, the zoo's acting director, has maintained that animal welfare is the zoo's top priority.

Peterson said after Tuesday's meeting that she was "grateful that our core mission was validated."

According to Peterson, currently 100 of the zoo's 752 animals are rescued animals, including a polar bear and two grizzly bears.

"We've always been committed to rescue," Peterson said, adding that the zoo may in the future "communicate more" with the public about the issue.

Peterson said the zoo now plans to introduce a new fundraising campaign to help pay for modernization of the zoo's aging facilities.

Other plans in place include a recommendation by Mayor Gavin Newsom and Supervisor Bevan Dufty to add two more commissioners to the joint zoo commission of the city's Recreation and Parks Department and the San Francisco Zoological Society, who would focus specifically on animal welfare issues.

Supervisor Ross Mirkarimi, who supported the advisory committee amendment, said that questions remain about the zoo.

Why should the San Francisco Zoo "not be on par with the best?" Mirkarimi asked, citing as examples zoos in San Diego, Oakland and Washington, D.C.

"I couldn't agree more," Peterson responded after the meeting, to "either equal or exceed our peers in the zoological community," she said.

Carl Friedman, director of the city's Animal Care and Control Department, said he has seen "a myriad of improvements" at the zoo since he was appointed as a liaison to the zoo following the Christmas Day fatal mauling, including maintenance issues "being taken a lot more seriously," and improved communication between the city and the Zoological Society.

New security arrangements, including heightened enclosure walls, a new public address system, and posted warnings about "proper zoo etiquette" were also subsequently installed at the zoo after the mauling.

Friedman said of Peterson, who took over after the resignation in June of the zoo's previous director Manuel Mollinedo, that he was convinced "animal welfare will be her top priority."

"This has been a distraction," Friedman said of the legislative debate, which lasted months and included multiple, often contentious, public hearings.

"The real work," of fundraising, making improvements to exhibits, and implementing new zoo policies and procedures, "is yet to come," Friedman said.

"I do think that the issue has been framed," said Daly after the meeting, in anticipation of future negotiations over whether the city will renew its contract with the Zoological Society.