Three months after stranding on a Delaware beach, a gray seal dubbed Pippi Longstocking is recovering at the National Aquarium in Baltimore and will soon be released to the wild. She may be the facility’s last such patient for the foreseeable future.

The aquarium has lost more than $8 million and furloughed one-third of its staff since closing in March because of the coronavirus pandemic. Although its 20,000 animals — including 13 endangered sea turtles convalescing in a new rehabilitation center — are still being cared for, the institution’s rescues of stranded seals and other federally protected marine mammals can’t happen now.

The National Aquarium is one of more than 200 major U.S. zoos and aquariums that — like most attractions that rely on ticket sales — have suffered huge losses amid shutdowns to combat the spread of the coronavirus. But these zoos say they have been hit harder than many other shuttered institutions because their occupants — more than a million animals nationwide, some owned by the U.S. government — still need food, water, heating, cooling and veterinary care.

Helping wild animals such as Pippi is important to the aquarium, said president and CEO John Racanelli, but it takes “existential” resources that are vanishing. “Many of our peers are in tougher shape,” Racanelli said. “But all of us are confronting the fact that if we’re not operating, we’re dying.”

Many zoos have laid off or furloughed most staff members except those who care for animals, but they are hemorrhaging money even as some partially reopen, according to the Association of Zoos and Aquariums, which represents 229 facilities in North America. Their future tenuous, some of their first cuts are likely to be to wildlife conservation programs, some of which buttress federal efforts to rebuild endangered species populations, said Dan Ashe, the association’s president.

“The bottom line is that it’s been financially devastating for our members,” Ashe said. Most zoos, he said, have three to six months of financial reserves, and the federal paycheck protection funds received by about 70 percent are running out. “The casualty, I’m almost certain, will be the ability to support conservation work. Because that’s fueled by gate revenue,” he said.

Critics dismiss zoos’ contributions to species conservation — within their gates and in the wild — as window-dressing to justify keeping animals for entertainment, and some zoos devote more of their budgets to conservation than others. But through captive breeding, research and rehabilitation, U.S. zoos say they play a key support role to the U.S. Fish and Wildlife Service and the National Oceanic and Atmospheric Administration, which are required to try to recover animals on the endangered species list.

Breeding of endangered species is on hold at many zoos. The Endangered Wolf Center, near St. Louis, in May flew nine critically endangered Mexican wolf pups to Arizona, where they were placed with wild foster mothers. But it was able to afford the trip only because donors provided private planes.

The Saint Louis Zoo pulled nearly $900,000 in money designated for conservation programs, including one dedicated to monitoring and reintroducing the endangered American burying beetle. Omaha’s Henry Doorly Zoo and Aquarium permanently closed its plant conservation center, known for its work to propagate a Bermuda fern not seen in the wild since 1905.

“If it weren’t for zoos, the federal government couldn’t take care of species that face extinction in the wild,” said Jeffrey P. Bonner, president of the Saint Louis Zoo, which says it spends more than $500,000 a year caring for animals on the endangered species list, including 1,840 Ozark hellbender salamanders. “We are on the front lines, and we aren’t getting any help.”

The zoo association is part of a coalition of cultural institutions asking Congress to provide relief in a future stimulus package. It also asked last month for $30 million for zoos and aquariums that participate in endangered species recovery or house animals rescued or confiscated by the government. Many of those animals are the property of the federal government, and without help, zoos may no longer be able to afford caring for them, Ashe wrote in a request.

By the association’s calculation, rescue and rehab of protected sea turtles costs 40 aquariums a total of $450,000 a month. Breeding and caring for endangered black-footed ferrets: $200,000 a month. A new government-managed program at 18 aquariums to house and propagate corals experiencing massive die-offs in the Florida reef tract totals more than $1 million a month, the Association of Zoos and Aquariums said.

And then there are about 80 giant Thai catfish at the Georgia Aquarium. The fish, critically endangered in the wild, were confiscated as babies from an illegal fish farm by federal authorities more than a year ago and taken by the aquarium for holding at an off-site facility. They weigh about two pounds now, the aquarium says, but they can become more than five feet long — and take up far more space than one aquarium can provide.

Ashe said the aquarium’s efforts to place the fish at other aquariums have mostly been unsuccessful. Thailand doesn’t want them, and euthanizing them — which the Georgia Aquarium does not want to do — would require explicit federal permission. An aquarium representative said the catfish are being cared for by a team of specialists, which hopes to find new homes for them while they are still small.

Not all zoos are in dire straits. Some, such as Smithsonian’s National Zoo in the District, are government-funded. Others, including the Indianapolis Zoo, say they have sufficient reserves to last for much of the year with belt-tightening, though they would welcome government help.

“It’s a challenging time to ask for additional funding when we know that the human cost is incalculable,” said Rob Shumaker, president of the Indianapolis Zoo, which has about 250 staffers. “But when we talk about the human cost, it’s about 250 families that are relying on us here at the zoo.”

Some zoos have come up with ways to stanch the bleeding. The San Antonio Zoo, which earns all of its revenue from ticket sales and donations — much of it tied to Texas oil money that has tanked in the markets — opened a wildly popular “drive-through zoo” in May. About 1,000 vehicles a day tooled through safari-style, their passengers buying Dippin’ Dots from vendors who approached vehicle windows and getting out one-by-one to use bathrooms, to allow for sanitizing between each pit stop. The money helped, but the zoo, which partially reopened in late May, is “still coming out of this millions of dollars in the hole,” said CEO Tim Morrow.

“Zoos are seeing that as soon as they open, everyone thinks everything is okay,” said Bert Vescolani, president and CEO of the Denver Zoo, which is working on a reopening plan that will involve herding visitors through paths formed by hay bales and keeping indoor areas closed. “The fact of the matter is, we will be at half our attendance, so we won’t be able to cover our expenses even being open.”

The Calgary Zoo announced in May that it would send its two pandas to China after flight cancellations made it difficult to procure sufficient bamboo to feed the animals. Leaders of zoos represented by the Association of Zoos and Aquariums insist their financial woes will not lead to animals suffering or to euthanasia, which one German zoo recently said was an option. But they said they would be far less able to take in animals from smaller, private zoos that might have even deeper troubles.

Ron Kagan, director of the Detroit Zoo, said he is confident donors or the government would step in before zoo animals starved. “Ultimately, society would decide that this just can’t happen,” Kagan said.We can’t have animals die, and certainly we can’t kill them.”

But even major zoos may be permanently changed by the pandemic. The still-closed Detroit Zoo has put forth a strong public face — it’s sharing educational videos about flamingo rescues and animal ultrasounds on Facebook, and newborn prairie dogs are starring in one of five livecams. But it has laid off half of its staff and is losing more than $2.5 million a month.

“We can’t help but watch the resources drain and begin to wonder when does this become a life-threatening crisis for the organization,” Kagan said. Asked where additional cuts could cut from, he said: “I’m sure we’ll be smaller, meaning we’ll have fewer people, and we’ll have less money.”

At the Endangered Wolf Center, which has helped increase the wild population of Mexican wolves from near zero in the 1970s to more than 160 last year, the resident canines’ diets have changed a bit. With fewer donated deer carcasses from hunters coming in, the 41 Mexican and red wolves are eating more dry chow and hunting more raccoons in their wild-like habitats, said Regina Mossotti, director of animal care and conservation.

The small center remains closed to the public, whose entry fees fuel its $1 million annual budget. But the staff — about one-sixth smaller following layoffs — was elated to have been able to place the wolf pups with wild packs in Arizona, she said.

“When things like covid happen, those animals still need to be cared for, and the recovery efforts and conservation efforts still need to push forward,” Mossotti said. “We still need to save these endangered species. And the pandemic has made that very challenging.”