Outraged ecologist Derek Gow shared the picture on social media describing it as “murderous, callous, cruel”.
It is understood the beaver was pregnant and found not far from Crieff, Perth and Kinross.
A post-mortem examination is said to have shown it had been shot in the head with a shotgun, which didn’t kill it, and was later “finished off” with a rifle.
Derek, whose efforts were crucial in reintroducing beavers to Britain, said: “You can see the bullet wounds. Some others worse.
“No justification at all that’s credible.
“This is the guardians of the countryside on a moral norm.
“Shooting, bludgeoning, butchering.”
Environmentalist Ben Goldsmith also shared the picture stating: “Another dead beaver, also pregnant, found not far from Crieff.
“Post-mortem showed it to have been shot in the head with a shotgun, which didn’t kill it, later finished off with a rifle.
“She suffered greatly.
“There are fewer than a thousand beavers in Britain. This is an outrage.”
Other shocked users described the attack as ‘disgusting’ and ‘awful’.
On May 1 the Scottish Government brought into force a new regime giving beavers legal protection.
To kill them, or destroy their dams or lodges, people have to be granted a licence by Scottish Natural Heritage (SNH).
Wildlife campaigners celebrated the decision, emphasising the widespread ecological benefits of the beavers’ reintroduction.
But farming leaders have previously raised concerns about the damage caused to agricultural land from their dam-building.
A spokesman for Scottish Natural Heritage said: “We can confirm this beaver wasn’t shot under licence.
“If it was shot after May 1, it is an offence.
“We understand the SSPCA will be investigating this further.
“Beavers are now a protected species.
“Anyone suspecting an offence has been committed should contact Police Scotland.”
The Scottish SPCA confirmed they are investigating the incident.
Chief superintendent Mike Flynn said: “We can confirm we are investigating a report of a deceased pregnant beaver who appears to have been killed unlawfully.
“This is an ongoing investigation so we cannot make any further comment at this time.
“Legislation to protect beavers was put in place on 1 May and outlines that as a way of minimising the impact on land use in some areas, the culling of beavers can be carried out but only by licensed and trained persons using humane methods which avoids unnecessary suffering.
“We want to ensure the welfare of beavers in the wild and any dependent young they may have.
“Beavers are a fascinating species, capable of the intricate engineering of dams and they can have a positive impact on their surrounding environment and ecosystem.
“The Scottish SPCA will be investigating all reports of the killing of beavers where welfare has been compromised.
“If anyone has any information, please phone our confidential animal helpline on 03000 999 999.”