French authorities performing an autopsy on an orca who died in the Seine River, near the northern city of Rouen, have found a bullet lodged at the base of the animal's skull. The NGO Sea Shepherd France said it would file a legal complaint to clarify what happened.
In a statement, the Seine-Maritime prefecture said it was impossible to make any link between the bullet and the orca's death.
The animal died at the end of May after spending several weeks swimming up river.
A team of veterinarians carried out the autopsy a day after the orca died. They learned it was an "immature" female, 4.26 metres long and weighing 1,100 kilogrammes when it died.
Analyses of the killer whale's organs and skin did not find evidence of any bacterial infection or a fungal infection, which had initially been suspected as a possible cause of its distress.
Starved to death
The prefecture said the likely immediate cause of death was weakness from starvation, as the animal had stopped eating after having been separated from its pod.
Authorities tried unsuccessfully to guide it back to the English Channel using sound and other methods.
The bullet was found in the tissue at the base of the skull, with no sign of trauma found on its skin.
It is “not possible to date the moment the bullet penetrated the animal’s body” the prefecture said in a statement.
The Rouen prosecutor was informed of the discovery of the bullet, and will determine the next steps.
The ocean campaign group Sea Shepherd France said on Tiwtter it intended to file a lawsuit “for attempted destruction of an endangered species”.
Other more general analyses of the orca's teeth as well as the presence of polluting chemicals are expected within a few months.
The carcass is now with the National Natural History museum, which will prepare the skeleton to be included in its collection of mammals.
Another whale in the Seine
Meanwhile, what appears to be a 10-metre-long minke whale was spotted in the Seine, close to the English Channel, at the end of June.
The Seine-Maritime prefect said an emergency meeting with researchers and state officials had been held after sailors first spotted the animal on 30 June.
The GECC mammal research institute, which was involved in tracking the orca, is now monitoring the minke whale, which appears to be in good condition.
Sea Shepherd France on Monday said it had spent 10 hours searching for the whale without success, concluding it may have gone back out to see.
The presence of the whale in the Seine is unusual, but not as unprecedented as the orca.
The prefecture has put out a warning for boats in the area, prohibiting anyone from coming within 100 metres of the whale.