A new report has linked BP oil spill to dolphin deaths in the Gulf of Mexico.

The study was conducted by researchers at the National Oceanic and Atmospheric Administration and colleagues. They found that the kind of lung damage and hormonal changes seen in Bottlenose dolphins in Louisiana's Barataria Bay are different from any other disease ever documented in dolphins. Barataria Bay was badly affected by The Deepwater Horizon spill. 

Researchers said that the mammals in the heavily oiled regions of the bay are showing signs of damage seen in dolphins that were exposed to petroleum hydrocarbons in the laboratory.

That's not all. The study says that the toxic effects of the oil spill are likely to reduce reproductive ability of the dolphins living in the region. It was conducted as a part of Natural Resource Damage Assessment (NRDA) in 2011.

In the study, researchers examined 29 dolphins from Barataria Bay. They used ultrasound exams to assess lung condition of each mammal. About 48 percent of the animals were in bad condition while 17 percent of them weren't expected to survive for long.

"I've never seen such a high prevalence of very sick animals - and with unusual conditions such as the adrenal hormone abnormalities," said Dr. Lori Schwacke, the study's lead author in a statement.

The study is published in the journal Environmental Science and Technology

Barataria Bay dolphins were five times more likely than others to suffer from lung disease, researchers found. Also, these dolphins had low weight and had poor levels of adrenal hormones, which are essential for combating stress.

According to Jacqueline Savitz, senior campaign director of the Oceana conservation group, the report confirm that marine life in the gulf suffered huge losses after the oil spill.

"After the spill I saw dolphins swimming in and out of oil slicks, breathing air at the surface that I knew contained hydrocarbons from the spill since I could smell them myself," Savitz told The Guardian. "The dolphins were likely exposed to the oil in other ways as well, by swallowing water, and through their food. While we have seen an unusual number of dolphin deaths during and after the spill, this report verifies that the oil took a larger toll on dolphins."

Researchers have conducted additional tests this year. The team hasn't released those results yet.