Twenty-seven marine biologists penned a letter to President Barack Obama on Thursday urgently asking him to defer seismic exploration in the Atlantic Ocean that could lead to the extinction of North Atlantic right whales.

Right whales are already one of the worlds most critically endangered whale species , two of the letter's authors Douglas Nowacek and Andrew Read said in a Duke University statement. There are fewer than 500 whales, according to recent estimates. The decreasing number of right whales is "directly linked to the disproportionately high level of human activity" the letter said.

"This is an animal that has persisted through centuries of past whaling, Howard Rosenbaum, one of the letter's authors and the Wildlife Conservation Society's Ocean Giants Program director, told The Huffington Post. The species is no longer increasing in abundance and may be declining in numbers. It also suffers from getting hit by ships and fishing gear entanglement. We also know that elevated noise levels in their environment cause stress."

In addition to elevated stress levels, seismic surveys can "disrupt vital communication such as between mother and calf," he added. The surveys are "adding yet another major stressor into their already-stressed environment."