The Georgia Aquarium lost another round in its bid to import 18 beluga whales from Russia as a federal judge sided with the federal government in blocking import of the mammals.

U.S. District Court Judge Amy Totenberg said the National Oceanic and Atmospheric Administration properly reviewed the aquarium’s application. She rejected the aquarium’s argument that the agency’s denial was “arbitrary and capricious.”

The belugas are a popular attraction at the aquarium, which draws more than 2 million a visitors a year to downtown Atlanta. But two beluga calves born there in recent years have died.

Aquarium officials said the wild-caught whales are needed to improve research efforts and bolster the gene pool of belugas in captivity. Some of the the whales sought by the aquarium would have displayed in Atlanta, while some would have gone to the Shedd Aquarium in Chicago as well as several Sea World parks.

The 1972 Marine Mammal Protection Act bans the import of mammals except in certain circumstances, such as public display. In 2012 the aquarium applied to NOAA to import the belugas, the first such application in more than two decades. NOAA denied the application, saying that allowing the import could open the door to widespread hunting and collection of belugas and other mammals.

In September 2013, the aquarium sued. It’s unclear whether they will appeal the decision.

The 18 belugas in question were were captured between 2006 an 2011 in the Sea of Okhotsk, off the northeast coast of Russia. They are currently being held at the Utrish Marine Mammal Research Station in Russia.