Dallas, Texas (CNN) -- The Dallas Safari Club auctioned off a black rhino hunting permit in Namibia for $350,000, according to the club's public relations firm.
Wealthy hunters gathered Saturday evening inside the Dallas Convention Center to bid on the rare chance to hunt one of the world's most endangered animals.
The Safari Club says the auction was done in the name of conservation, to save the threatened black rhinoceros. All proceeds will be donated to the Namibian government and will be earmarked for conservation efforts, club officials say.
Animal conservationists estimate there are only about 5,000 black rhinos in the world, 1,700 of which are in the southern Africa nation. They are considered a "critically endangered species" by wildlife organizations around the world.
"This is the best way to have the biggest impact on increasing the black rhino population," said Ben Carter, executive director of the Dallas Safari Club.
Sacrificing one animal for the greater good of the endangered species is a move that critics and animal conservation groups call "perverse" and a "sad joke."
"They need to be protected, not sold to the highest bidder," said Jeffrey Flocken of the International Fund for Animal Welfare (IFAW). "It also sends a dangerous message that these iconic and disappearing animals are worth more as dead trophies to be mounted and hung on a wall in a Texas mansion than living in the wild in Africa."
Helping or hurting the species?
The auction has sparked a contentious debate over the best way to protect the species that has been brought to the edge of extinction because of man's appetite for its horn, which is used for daggers, ornaments and, in Asia, traditional medicine.
The Dallas Safari Club said it has received a string of death threats over the auction. The FBI is investigating the threats.
"If a violation of federal law is determined, then additional investigation will take place if necessary," said Katherine Chaumont, spokeswoman for the Dallas FBI office.
The club obtained the hunting permit from the Namibian government. It's the first time a black rhino hunting permit has been auctioned off outside the country.
In recent years, the Namibian Ministry of Environment and Tourism, which oversees the protection of the black rhinos, has allowed three permits a year.
In a letter to the Dallas Safari Club, the Namibian government said, "To hunt a black rhino is not taken lightly by Namibia. ... Only old geriatric bulls, which are marginalized in the population and do not contribute to reproduction, are trophy hunted."
The Dallas Safari Club says the Namibian government will closely monitor the winning bidder's hunting expedition. The club also insists that by allowing a handful of predetermined rhinos to be killed, it's actually protecting younger, stronger rhinos.
"They've already picked out two or three black rhino males that are old, nonbreeding males that are not contributing to the population anymore," Carter said. "We know it's the right way to do it. We're relying on science and biologists. This is the best way to support the population of black rhinos."
But some wildlife conservationists say that argument is dubious.
"It's a farce to say that this is being done for conservation," Flocken said. "It's saying the rarity of this animal is worth more dead than alive."
Several groups such as IFAW argue it would be better to use these rhinos to promote wildlife viewing and ecotourism by charging people for the experience of seeing one of these ancient beasts up close in the wild.
'It really is a dilemma'
The biggest threat to these massive beasts is poachers across the African continent. Rhino horns are lucrative on the black market. In Asia, where there are claims it can treat everything from headaches and food poisoning to rheumatism and cancer, horns can fetch up to $60,000 per kilogram, putting its value somewhere between gold and pure cocaine.
In the 1980s, the black rhino population had dwindled to just a few dozen. Conservation efforts have slowly helped beef up herd numbers, but poachers are still a threat.
Marcia Fargnoli, chief executive officer of the Save the Rhino Trust in Namibia, which works with the government to fight poachers, says the group has tried to convince the Namibian government to stop issuing these hunting permits.
But a poor African country like Namibia -- where the World Bank estimates the gross per capita income to be less than $6,000 -- struggles to fund conservation efforts, Fargnoli says. It's difficult for the government to ignore the chance to raise so much money so quickly.
"I really believe every rhino counts," said Fargnoli. "It really is a dilemma. ...But I really struggle to say I'm saving rhinos and then say that one can be hunted."
CNN's Jason Morris contributed to this report.