The bodies of almost 90 elephants have been found in the largest discovery of poaching in Africa.
An elephant is described a "fresh" when it is killed within the last three months, but a majority of the elephants found near the delta died in recent weeks, NPR reported, citing an Elephant Poaching Incident Report Reference written by Chase.
The government disarmed its anti-poaching units in May - a month after President Mokgweetsi Masisi was sworn into office.
"I'm shocked, I'm completely astounded".
JOHANNESBURG-Botswana, long viewed as a rare refuge for African elephants, is coming under increasing threat from poachers.More news: Russian Federation to end USA space station rides in April, pressuring NASA
The charity thinks an estimated one third of Africa's elephants have been killed in the last 10 years and Tanzania has lost around 60 percent of its elephants in the last five years. In June, some members of Botswana's parliament presented a motion to end a ban on elephant hunting, citing increased population and human-wildlife conflict as a reason.
Since then poachers have been breaching the border. Armed anti-poaching units in one 2016 article were credited with killing a sizable number of cross-border poachers to include 30 Namibians and another 22 Zimbabweans over a two-decade period.
'Clearly we need to be doing more to stop the scale of what we are recording on our survey'.
A similar census in 2014 found just nine carcasses, according to data provided by Mike Chase, director of Elephants Without Borders.More news: Reuters Journalists Jailed by Myanmar
A senior official in the president's office, Carter Morupisi, said that the "government has chose to withdraw military weapons and equipment from the Department of Wildlife and National Parks", but did not explain why.
The survey area is split into sections, or transepts, and the plane flies back and forth like a lawnmower cutting the grass - turning at each end to ensure nothing is missed.
While the move may have alleviated tension with Botswana's neighbours, conservationists believe it could be providing an opening to emboldened ivory traffickers.
Dr Chase added: 'Our new president must uphold Botswana's legacy and tackle this problem quickly.More news: Typhoon Jebi whips up monster waves, makes landfall in Japan