His eagle-eyed find has led to him winning the best Loch Ness Monster sighting of 2014, a competition run by bookmaker William Hill.
The Google image, taken above Horse Shoe Scree on the loch's southern side, was chosen from five contenders in the annual contest.
The curious snap topped an online poll on the Inverness Courier's website, which attracted a total of 92,000 votes, and was confirmed by judges to be the year's most intriguing image.
Mr Sjöstrand said: "I'm very happy to have won the prize. I am very interested in anything regarding Nessie and the history of Loch Ness.
"The reason I found this image on Google Earth was that I was sitting one night at home reading about Nessie and Loch Ness on the internet and thought I would check to see if I could see something from above - and that proved to turn out well.
"I have never been to Scotland but my hopes are that one day I will visit Loch Ness."
Gary Campbell, who keeps the official register of Loch Ness Monster sightings, said Mr Sjöstrand's find echoed other reports of large eel-like objects in the water.
I am very interested in anything regarding Nessie and the history of Loch Ness
"I would like to see further analysis of the photograph carried out."
He added the result showed the continued international interest in Loch Ness and the mysterious monster.
"Nessie is much bigger globally than people realise," he said.
His sentiments were mirrored by Rupert Adams, public relations manager for William Hill, who said the number of votes cast demonstrated the popularity of the monster mystery.
Mr Sjöstrand won £500 for his fascinating image, and all five finalists received a £50 bet on the winner of the William Hill Scottish Cup.