They may look fierce, but gorillas are no match for poachers who are hunting them so relentlessly the massive animals could soon be wiped out from their home in the Republic of Congo.

As many as 100 gorillas a year are slaughtered by poachers and sold for bush meat in a single region in the Republic of Congo, an environmental group tells the BBC.

If poaching in the region continues at its current rate, gorillas could last another decade, but not longer.

SLIDESHOW: The World's Largest Primates.

Endangered Species International carried out an undercover investigation in Kouilou, a region 80 miles North from the Congo city of Pointe-Noire, the country's second-largest city and a major port. The team tracked the gorilla population and observed the poachers in the field.

"According to interviews and field surveys, we think we may have about 200 gorillas left in the area," Pierre Fidenci, the group's president, told the BBC.

"But we estimate that four percent of the population is being killed each month, or 50 percent in a year. It is a lot," he told the BBC.

The primary target for poachers — adult males at the prime age for reproduction. These gorillas have the most mean and will therefore earn the most money for poachers.

Click here for the full report from the BBC.