It was a shocking sight popping up all along Gulf beaches last year; dead dolphins just washing ashore.
A doctor said that it was by definition an unusual mortality event.
There were more than 180 dolphins counted on beaches between Louisiana and western Florida.
At the time many didn't know what was going on, but found it all to peculiar that it was all happening not too long after the massive BP oil spill.
But now a year later researchers are releasing findings from a study that looked into what's behind the spike in deaths.
“What we were interested in was whether these physical processes; the movement of the currents, the flow of the water and the temperature was at all related to where these animals were washing ashore and when they were washing ashore,” Dr. Ruth Carmichael, Marine Biologist, said.
Their conclusion -- a perfect storm -- of factors likely contributed, rather than one main event.
Biologists said that in addition to the oil spill, temperatures in the water were unusually cold.
“We had animals that were already stressed, and already sick, that may have had bacterial infections or may have been otherwise compromised that were in our waters that may have been exposed to these freight trains of cold fresh water,” said Carmichael.
These scientists are ruling out the possibility of exact causes of deaths , but if there is they say at this point they don't know what it is.
So critics of the study say it's a premature search for answers.
“Even though it is a possibility that it [BP spill] is a factor,” Dr. Moby Solangi, with The Institute for Marine Mammal Studies, said. “We're not questioning that.”
“But the conclusion that it could have been a major contributing factor to the deaths of the animals are not truly verifiable by their study,” said Solangi.
Researchers said they will not have a definitive answer on the cause of death until more data is released by the National Oceanic and Atmospheric Administration.