Despite living in a place considered a sanctuary for them, nearly 90 dead elephants have been discovered by aerial surveys in Botswana.

All of them were assumed to have been poached for their tusks.

"I'm shocked, I'm completely astounded. The scale of elephant poaching is by far the largest I've seen or read about anywhere in Africa to date," Mike Chase from Elephants Without Borders told BBC News.

A sanctuary, violated

The elephant carcasses were discovered during aerial surveys conducted by Elephants Without Borders.

"All carcasses [were] presumed to be poached, because all of them had their skulls chopped to remove their tusks," Chase wrote in an incident report about poaching obtained by NPR. "Poachers tried to hide their crimes by concealing the mounds of rotting flesh with drying bushes."

The report also made mention of three white rhinos having been killed over the last three months in the same area.

"The varying classification and age of carcasses is indicative of a poaching frenzy which has been ongoing in the same area for a long time," Chase concluded in the report.

The carcasses were found in the Okavango Delta wildlife sanctuary. The sanctuary, covering almost 8,500 square miles (22,000 square kilometers), is a major tourism draw.

Botswana is home to roughly 130,000 elephants, according to BBC News, making it a sanctuary of sorts for the animal. Indeed, tracking collars show that elephants from other countries, including Angola, Namibia and Zambia, will migrate and stay in Botswana due to the perceived safety of the country.

The demise of anti-poaching squads

Elephants stand side-by-side in Botswana Botswana contains 37 percent of Africa's known elephant population. (Photo: Jeremy T. Hetzel/Flickr)

The safety had been reinforced by strong anti-poaching efforts. Botswana does not have fences around its international borders, instead relying on armed anti-poaching units to patrol the areas. This recent rash of killings happened deep within the country, however.

"People did warn us of an impending poaching problem, and we thought we were prepared for it," Chase said to BBC News.

"The poachers are now turning their guns to Botswana. We have the world's largest elephant population and it's open season for poachers."

Chase's assertion that it's open season for poachers comes on the heels of a move by President Mokgweetsi Masisi, who disarmed the anti-poaching units shortly after coming into office in April. Journalists in Botswana at the time were informed by a senior official that "government has decided to withdraw military weapons and equipment from the Department of Wildlife and National Parks," but were not given any additional information about why the decision had been made.

"Botswana has always been at the forefront of conservation and it will require political will," Chase told BBC News.

"Our new president must uphold Botswana's legacy and tackle this problem quickly. Tourism is vitally important for our economy, jobs, as well as our international reputation, which is at stake here as being a safe stronghold for elephants."

Poachers kill 87 elephants in Botswana
Incidents of poaching in Botswana are rare, but the nearly 90 dead elephants come just as the government disarmed its anti-poaching units.