NOAA Fisheries announced Tuesday it is denying a request made by the Georgia Aquarium in Atlanta for 18 beluga whales from Russia for public display.

The decision, the agency reports, was based on requirements of the Marine Mammal Protection Act (MMPA), which allows marine mammals to be removed from the wild or imported for the purpose of public display as well as providing a process for issuing permits.

The request represented the first application for a permit to import recently caught wild marine mammals in more than 20 years, NOAA said in a press release.

According to Sam Rauch, acting assistant NOAA administrator for NOAA Fisheries, the aquarium "clearly worked hard to follow the required process and submit a thorough application." 

"However," he added, "under the strict criteria of the law, we were unable to determine if the import of these belugas, combined with the active capture operation in Russia and other human activities, would have an adverse impact on this stock of wild beluga whales."

Specifically, NOAA Fisheries said it was unable to discover whether the import of the animals would have a "significant adverse impact" on the Sakhalin-Amur beluga whale stock from which the 18 were taken. Furthermore, the agency said they found the requested import would likely result in "the taking of marine mammals beyond those authorized by the permit."

Finally, five of the beluga whales in the group were estimated to be under two years old at the time of capture, meaning they were possibly still nursing and not in a position to live independent of their mother.

The whales were captured between 2006 and 2011 in the Sea of Okhotsk,  

Belugas are social animals that typically migrate, hunt and interact in groups ranging in size from 10 to several hundred in the arctic and subarctic waters of Russia, Greenland and North America.

According to NOAA, the animal faces a myriad of threats, including ship strikes, pollution, habitat destruction and entanglement in fishing gear. They are listed as near threatened by the International Union for Conservation of Nature (IUCN).