The humpback whale calf, believed to be less than a year old, was found with ropes and a lobster pot entangled with its tail a mile off the coast of Lybster, Caithness.
The whale’s body was already partially decayed, suggesting it had been dead for 1-2 weeks.
The suspected cause of death is drowning as a result of entanglement.
For some species of whale, entanglement is considered the primary cause of death in Scottish waters.
Cal Major, a vet and world record stand up paddleboarder who found the whale, said: “I knew that entanglement was a big issue with seals and sea birds but actually to see it for myself is really heartbreaking.
"To think that such a huge animal could succumb to human activities in this way is devastating.”
Major found the whale during her SUP-ing expedition, having set off from Glasgow in mid May.
Her expedition is raising money for Seaful, the charity connecting more people to the sea.
She is also investigating the crucial role that our ocean plays in the climate and biodiversity crisis ahead of COP26
Major hopes that ocean health will be brought higher on the agenda for COP26.
She said: “The importance of our ocean is often overlooked, and devastating harm is being done without us being able to see it.
“This whale is just the tip of the iceberg - a very stark and visual reminder of how vulnerable wild animals, even some of the largest in the world, are to man’s
"Entanglement is just one issue facing whales and dolphins; overfishing, bycatch, dredging and trawling (which are hugely damaging to the seabed) and pollution are all unbalancing the ecosystem and killing marine life.
“When will the Scottish and UK government sit up and take action to properly protect our seas?”
A Scottish Government Spokesperson said: “We are working with the other UK administrations to develop a programme of measures under the UK Marine Strategy to address pressures on the marine environment and improve the health of our seas.
"This programme will be the subject of a public consultation later this year.”