Published: Jan 24, 2014 9:37 PM EST
Updated: Jan 24, 2014 11:16 PM EST

COLLIER COUNTY, Fla.- Six days after mysteriously swimming into the Naples Bay, 25 pilot whales are dead and it's up to these marine biologists to find out why.

"The animals did appear thin, there were no external signs of human interaction that we could see, we weren't able to examine everybody inside, but no obvious signs of human interaction," said Gretchen Lovewell with Mote Marine Labratory.

Experts from several agencies spent all day Friday on Kice Island, studying the whales.

"Definitely a team effort."

But biologists said due to time and the decaying condition of many of those whales, only six full necropsies were performed.

"The animals are starting to decompose, so as the tissues are starting to degrade, we lose information. However we did document all of the animals."

And unlike earlier this week at Lover's Key, where crews removed all eight dead whales, these 25 will stay on Kice Island.

"There's a whole lot of vultures out there, scavengers, natures pretty remarkable so I cant imagine, it'd be several weeks," said Lovewell.

It could also take months before biologists get the results of the necropsies and find out why these whales died. But new tonight, after speaking with the Navy, NOAA can now rule out sonar as a cause of their confusion and stranding.

"Sometimes a stranding happens and you can't find a straight answer. And for pilot whales, which are very socially cohesive, sometimes this happens and this is what they do, they stay together and ended up dying the whole group together," said Laura Dias with NOAA.