Dallas (CNN) Corey Knowlton is, at last, moving forward with plans to hunt a black rhinoceros in Namibia this year, re-kindling a debate over conservation methods and the future of an endangered species.

Because rhinos' first instinct is to seek out other herds, and Botswana has a low rhino density, synthesized rhino dung is used to help the relocated animals establish their territory.

How to save a rhino – Because rhinos' first instinct is to seek out other herds, and Botswana has a low rhino density, synthesized rhino dung is used to help the relocated animals establish their territory.

Rhino candidates are sedated and their blood samples studied to make sure they're strong enough to make the trip. The rhinos then recover during a six-week quarantine before they're moved by plane to a secret location in Botswana.

How to save a rhino – Rhino candidates are sedated and their blood samples studied to make sure they're strong enough to make the trip. The rhinos then recover during a six-week quarantine before they're moved by plane to a secret location in Botswana.

Rhinos Without Borders has partnered with tourism venture andBeyond (pictured), who moved rhinos from one of their private reserves to Botswana in 2011. It costs roughly $45,000 to move a single rhino.

How to save a rhino – Rhinos Without Borders has partnered with tourism venture andBeyond (pictured), who moved rhinos from one of their private reserves to Botswana in 2011. It costs roughly $45,000 to move a single rhino.

One of the reason's Botswana's poaching level is so low is its zero tolerance for poachers. Anti-poaching is handled by the Botswana Defense Force, who have a "shoot to kill" policy, meaning if a poacher doesn't immediately put down his weapon, the military can treat him like a threat.

How to save a rhino – One of the reason's Botswana's poaching level is so low is its zero tolerance for poachers. Anti-poaching is handled by the Botswana Defense Force, who have a "shoot to kill" policy, meaning if a poacher doesn't immediately put down his weapon, the military can treat him like a threat.

Beverly and Dereck Joubert (pictured) are a husband-and-wife team of filmmakers and photojournalists for National Geographic. They recently started Rhinos Without Borders, a charity that plans to move at least 100 black and white rhinos from South Africa to Botswana, where poaching is nearly nonexistent.

How to save a rhino – Beverly and Dereck Joubert (pictured) are a husband-and-wife team of filmmakers and photojournalists for National Geographic. They recently started Rhinos Without Borders, a charity that plans to move at least 100 black and white rhinos from South Africa to Botswana, where poaching is nearly nonexistent.

There are only 5,000 black rhinos left on the continent (a 96% reduction since 1970). The white rhino story is a happier tale. Rescued from the brink of extinction, the species now numbers 20,000 -- though conservationists worry they too are in danger, as rhino horn continues to sell for a hefty sum on the black market.

How to save a rhino – There are only 5,000 black rhinos left on the continent (a 96% reduction since 1970). The white rhino story is a happier tale. Rescued from the brink of extinction, the species now numbers 20,000 -- though conservationists worry they too are in danger, as rhino horn continues to sell for a hefty sum on the black market.

In Eastern Asia, rhino horn is (inaccurately) believed to cure a range of maladies, from cancer to fever. It is also sold as an aphrodisiac. The horns sell for as much as $65,000 a kilogram on the black market.

How to save a rhino – In Eastern Asia, rhino horn is (inaccurately) believed to cure a range of maladies, from cancer to fever. It is also sold as an aphrodisiac. The horns sell for as much as $65,000 a kilogram on the black market.

How to save a rhino – In 2013, over 1,000 rhinos were killed for their horns.

South Africa has the highest concentration of black and white rhinos in Africa. They also have the highest rate of poaching.

How to save a rhino – South Africa has the highest concentration of black and white rhinos in Africa. They also have the highest rate of poaching.

The auction for an opportunity to hunt a black rhino, considered "critically endangered" by wildlife organizations around the world, was held inside the Dallas Convention Center on a chilly evening in January 2014.

In recent years, the Namibian Ministry of Environment and Tourism had allowed three permits a year, and Knowlton's permit marked the first time a black rhino hunting permit had been auctioned outside the country.

The population of Yangtze finless porpoises is declining rapidly. The freshwater dolphins are suffering due to pollution and hunting.

Yangtze finless porpoise – The population of Yangtze finless porpoises is declining rapidly. The freshwater dolphins are suffering due to pollution and hunting.

Western lowland gorillas are critically endangered species. Because of poaching and disease, their numbers have declined by more than 60% over the last 20 to 25 years, according to the WWF's report.

Western lowland gorilla – Western lowland gorillas are critically endangered species. Because of poaching and disease, their numbers have declined by more than 60% over the last 20 to 25 years, according to the WWF's report.

Leatherback turtles are the largest sea turtle species and also one of the most migratory, crossing both the Atlantic and Pacific Oceans. According to WWF, their numbers have seriously declined during the last century as a result of intense egg collection and fishing.

Leatherback turtle – Leatherback turtles are the largest sea turtle species and also one of the most migratory, crossing both the Atlantic and Pacific Oceans. According to WWF, their numbers have seriously declined during the last century as a result of intense egg collection and fishing.

Sumatran tigers are the smallest surviving tiger species and are protected by law in Indonesia. But despite increased efforts in tiger conservation, they remain critically endangered.

Sumatran tiger – Sumatran tigers are the smallest surviving tiger species and are protected by law in Indonesia. But despite increased efforts in tiger conservation, they remain critically endangered.

Sumatran elephants come into conflict with humans due to the rapid expansion of palm oil plantations which destroy their habitat.

Sumatran elephant – Sumatran elephants come into conflict with humans due to the rapid expansion of palm oil plantations which destroy their habitat.

The South China tiger is considered "functionally extinct," as it has not been sighted in the wild for more than 25 years.

South China tiger – The South China tiger is considered "functionally extinct," as it has not been sighted in the wild for more than 25 years.

Amur Leopard, a rare species of leopard living on the borders of Russia and China, was the winner of the 2013 WWF award dedicated to the positive evolution of an endangered species, but remains critically endangered.

Amur leopard – Amur Leopard, a rare species of leopard living on the borders of Russia and China, was the winner of the 2013 WWF award dedicated to the positive evolution of an endangered species, but remains critically endangered.

As humans move more into the mountain gorillas' territory, the gorillas have been pushed farther up into the mountains, forcing them to endure dangerous and sometimes deadly conditions, the WWF report on the planet says.

Mountain gorilla – As humans move more into the mountain gorillas' territory, the gorillas have been pushed farther up into the mountains, forcing them to endure dangerous and sometimes deadly conditions, the WWF report on the planet says.

The existence of Hawksbill sea turtles have been traced back 100 million years. Now they are critically endangered, the WWF says.

Hawksbill sea turtle – The existence of Hawksbill sea turtles have been traced back 100 million years. Now they are critically endangered, the WWF says.

Poachers and hunters are responsible for the early decline of black rhino population. The world's animal population has halved in 40 years as humans put unsustainable demands on Earth, according to a 2014 report from the World Wide Fund for Nature

The black rhino at one point was brought to the edge of extinction because of humans' appetite for its horn, which is used for daggers, ornaments and, in Asia, traditional medicine, so the notion of an auction was contentious even before Knowlton submitted the winning $350,000 bid.

The subsequent debate over Knowlton's hunt was not totally civil, as auction organizers received death threats that had to be investigated by the FBI.

How could hunting help?

The Dallas Safari Club sponsored the auction and billed it as a fundraising effort to help save the endangered species. Animal welfare groups and many critics strongly opposed the auction's conservation approach, dubbing the "kill-it-to-save-it" rationale misguided, outrageous even.

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"If they would look beyond the headlines and beyond their own emotional reaction to it and read into it, I think a lot of them would have a different opinion," Knowlton told CNN in an exclusive interview.

The safari club and Knowlton said the auction was done in the name of conservation. All proceeds from the permit will be donated to the Namibian government and dedicated to conservation and anti-poaching efforts, according to Namibia's Ministry of Environment and Tourism and the U.S. Fish and Wildlife Service.

More than a year after the winning bid, Knowlton has received the green light from the USFWS to import the dead animal, the final step in the long process to move forward with his expedition.

In his first interview since receiving the permit, Knowlton remains passionate that his $350,000 will be an "extremely valuable tool" to help Namibia fight poachers.

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"I believe hunting through sustainable use is an awesome tool in conservation that can keep these animals going forever as a species," Knowlton said. "I look at it in a realistic way -- that I understand that we can't save one individual forever. Conservation and hunting can work 100% together and is one of the ways that can help these animals survive for your great grandkids, and it's been done for a long time before so it has a great track record."

The rhino earmarked to be hunted is near the end of its life, Knowlton stressed, and is not beneficial to the gene pool. It is, in fact, "a detriment to the population" because it's capable of harming or killing other younger black rhinos, he said.

This model of "sustainable use," Knowlton said , requires killing the animal, which is going to "die one way or another."

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"It's either time, it's either poachers, it's other black rhinos, or it's other predators," he said. "The second that black rhino falls over, the bloom is off that rose. There is no more ability to get anything for it."

Knowlton could have scheduled his hunt sooner, but he waited for the USFWS to allow the rhino "trophy" to be imported to Texas. Knowlton wanted to see the entire "conservation" process completely through before moving forward, he said.

"The entire point of the auction in the United States was to be able to import the carcass," he said. "That's why they had the auction here, in the hopes that it would bring more money to conservation than the previous permits they have sold in Namibia."

At odds with animal rights groups

The USFWS cited "clear conservation benefits" for granting two permits to import "sport-hunted trophies," both Knowlton's and a second permit for American hunter Michael Luzich.

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"The hunts are consistent with the conservation strategy of Namibia, a country whose rhino population is steadily increasing, and will generate a combined total of $550,000 for wildlife conservation, anti-poaching efforts and community development programs in Namibia," the USFWS said in a statement

The Endangered Species Act requires the agency to determine that the import will enhance the species' survival and not be "detrimental" to its survival.

"The future of Africa's wildlife is threatened by poaching and illegal wildlife trade -- not responsible, scientifically managed sport hunting," USFWS Director Dan Ashe wrote. "United States citizens make up a disproportionately large share of foreign hunters who book trophy hunts in Africa. That gives us a powerful tool to support countries that are managing wildlife populations in a sustainable manner and incentivize others to strengthen their conservation and management programs."

In the 30-day comment period allotted for feedback, which closed December 8, the USFWS received more than 135,000 petition signatures and 15,000 public comments opposing the permit. Many of the comments came as similar form letters.

The idea that sacrificing an animal can improve an endangered species' welfare is something critics and some conservation groups call a "sad joke."

Azzedine Downes, president of the International Fund for Animal Welfare, said he is "baffled as to why they would issue this permit. ... We are very upset about it. We just simply don't believe that trophy hunting has any place in serious conservation."

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Downes and others in the animal rights community further call it a "bankrupt notion" that must change.

"If that were a sound practice, if that is truly a scientific approach, then why have the populations dwindled? Why have they been struck down by poachers? If this is such a science-based approach, why are we in the situation that we are in?" he asked. "The thought that the only way we can come up with to save the species is to kill them -- that, I would say, we are in a situation where there's a paucity of imaginative thinking."

Jeffrey Flocken, who specializes in helping the black rhinos for IFAW, said there are other alternatives.

"Instead of killing it, they can be moved to a different area, be used to bring in photo tourism or eco-tourism -- something that doesn't kill the animal. People pay good money to go to Africa to see species like rhinos, and instead of just killing one for a quick monetary gain for a vainglorious American, it can be moved around to a different area if it is a problem with the herd," he told CNN.

IFAW is considering joining other groups, such as PETA, in legal action to stop the U.S. government from issuing such permits, Downes said. PETA will be filing a lawsuit against the USFWS for their "outrageous decision to allow two sports hunters to bring back the bodies of animals shot in cold blood to decorate their trophy walls," the group said.

Added Delcianna Winders, an attorney at the PETA Foundation, "These permits are fundamentally inconsistent with the purpose of the Endangered Species Act, which is to conserve endangered species, not to authorize their slaughter."

Helping or hurting?

Animal conservationists estimate there are 5,000 black rhinos in the world, about 2,020 of which are in Namibia.

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Michael Knight, chairman of the International Union for Conservation of Nature's African and Asian rhino specialist groups , said the Namibian black rhino populations have been growing at a healthy 7% per year, thanks to conservation efforts.

Of the upcoming hunt, Knight said, "In population terms, it's of minor significance, as we are talking about one old bull that would have contributed genetically to the rhino population already. In monetary terms, it's important as it generates funds that go directly into the wildlife products fund that feeds 100% back into rhino conservation."

According to the USFWS, Namibia's black rhino population more than doubled between 2001 and 2012, which the group says can be attributed to local communities joining the fight against poachers.

The World Wildlife Fund, which works with 100 different countries to provide conservation support and is not opposed to hunting programs that don't threaten endangered species, emphasizes that creating incentives for local communities has proven to be a successful method over their 50 years of conservation work.

"Local communities and species have benefited from this innovative and popular conservation approach through the creation of new jobs, additional food, and diversified livelihoods -- thereby creating incentives for communities to protect local wildlife populations and to conserve the habitat such populations depend upon," the fund says in one of its mission statements

Namibia was the first African country to incorporate protection of the environment into its constitution, and its conservation program has contributed to it having the largest free-roaming black rhino population in the world.

The Dallas Safari Club obtained the hunting permit from the Namibian government, which will oversee Knowlton's expedition.

In a 2013 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 biggest threat to these massive beasts is poachers. 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 fetch up to $60,000 per kilogram, putting the value somewhere between gold and pure cocaine.

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In the 1980s, the black rhino population had dwindled to a few dozen. Conservation efforts have slowly helped increase herd numbers, but poachers are still a threat.

Marcia Fargnoli, chief executive officer of the Save the Rhino Trust in Namibia, which works to fight poachers, said the group has tried to persuade the government to stop issuing permits, but a poor African country like Namibia -- where the World Bank estimates the gross per capita income is less than $6,000 annually -- struggles to fund conservation efforts, she said.

"I really believe every rhino counts," Fargnoli said. "It really is a dilemma. ... But I really struggle to say I'm saving rhinos and then say that one can be hunted."

A dangerous expedition

"If this had happened earlier, there would be more rhinos on the ground -- period, end of story. You would have $350,000 more to protect them, and you would have one of the problem causers out of the way," he said.

Officials with the Namibian Ministry of Environment and Tourism will be with Knowlton every step of the way to ensure the correct rhino is killed.

Knowlton wants to do the hunt "sooner rather than later," he said, and is hopeful he can do it before this fall.

"From what I understand, it's one of the thickest and nastiest areas in the country, and it's full of brush and it's probably one of the most dangerous hunts you can have happen over there," Knowlton said.

He plans to track the animal on foot and will be within 50 yards -- potentially as close as 25 yards -- of the rhino when he fires the shots, a daunting prospect when you consider a bull can weigh up to 3,000 pounds. He is adamant that everyone on this journey follows his five rules of hunting: "Safety, safety, safety, safety, and safety."

Asked what kind of gun one uses to kill a rhino, Knowlton responded, "Big."

After the hunt, he is planning to coordinate distribution of the rhino meat to Namibian villages, he said.

"It wasn't like I was a person hell-bent on going to kill a black rhino. I'm a person hell-bent on the survival of the black rhino, period," Knowlton told CNN.

Despite the backlash to his planned hunt, he's optimistic that all the attention will serve to benefit the species.

"I don't know if the black rhino ever got more awareness than it got over this situation, and with that hopefully it gives it a better chance of surviving in the future," Knowlton said.

"Maybe 100 years from now -- maybe it's delusions of grandeur -- but I hope people will look at it and say this was the turning point that got people to understand what it means to be a conservationist."