Amid criticism from animal conservation groups and protests from people on the street, the Dallas Safari Club followed through Saturday with its historic auction of a permit to hunt a black rhino in the African nation of Namibia.

When the auction was first announced in October, organizers said the permit could fetch up to $1 million on the auction block. When the gavel fell Saturday night in downtown Dallas, the hunting permit went to the high bidder for $350,000. The Dallas Safari Club has not released the name of the auction winner.

Bidders could participate in Saturday's silent auction by telephone, so the winning bid could have come from anywhere in the world.

The auctioned hunting license was granted by the government of Namibia, which issues five rhino-hunting permits per year for its population of about 1,750 black rhinos. The auction of the Namibian hunting permit was the first time one was made available for purchase outside of Namibia, according to The Associated Press.

The rhino to be hunted will be an older male beyond its reproductive years. The culling of such a specimen may benefit the overall rhino population there because a territorial older male can prevent younger, reproductively fit males from breeding.

Rhino populations have been dwindling around the world, driven by an increasingly affluent Asian community that places high value on rhino horn for its use in traditional medicine and in folk crafts.

Although global black rhino numbers are 90 percent lower than they were three generations ago, Namibia has a good track record for its own conservation of black rhinos, according to the International Union for the Conservation of Nature (IUCN).

Critics of the auction say that trophy hunting sends a mixed message for the conservation of endangered species. The Animal Legal Defense Fund (ALDF) said that the revenue brought in by the rhino-hunting permit and other auctions held by the Dallas Safari Club over its annual three-day convention will be used to further a pro-hunting agenda.

"Although the group claims its primary intent is conservation of the critically endangered black rhino, fundraising proceeds from the convention consistently go towards hunting and political advocacy of hunting interests," the ALDF said in a statement. "The Safari Club's auction will likely result in increased exposure and big dividends for the group, and convention sponsors and exhibitors, and could set a dangerous precedent for similar hunting clubs seeking to profit from selling rare permits to kill endangered animals."

About 40 protesters gathered outside the convention hall Saturday, the AP reported.

"There's less than 5,000 black rhinos left on the planet," one protestor said, "and if our kids ever want to see a rhino left in the wild, we can't be pulling the trigger on every one we say is too old to breed."

This will be the sixth hunt of a post-reproductive male black rhino in Namibia, the IUCN's Sustainable Use and Livelihoods Specialist Group said in an open letter.

Revenue generated by the rhino-hunting permit will given to the Namibian Game Products Trust Fund, which the IUCN open letter said has a "good record in supporting rhino conservation work."

Despite fervent criticism, many feel the hunting of one rhino in Namibia will not contribute to the decline of the species, and in fact, may even help it.

In the open letter, the IUCN expressed its support for the hunt, citing Namibia's "outstanding" conservation track record and a relatively low occurrence of rhino poaching there.

"From a conservation perspective, we believe there are sound and compelling reasons to support this auction, and do not see any valid basis for opposing it," the conservation group said.