As the 37-year-old was swimming back to his board, the shark bit his shoulder and torso.
He was able to climb back onto his board and wait for rescue
The air condition engineer was picked up by the island rescue service and taken into shore.
“He sustained critical bite wounds to his torso and is lucky to be alive, only kept so by the heroics of the small US and UK medical teams on island, and because of the donated blood supplies of volunteers,” Daniel Schempp, commander of the US Air Force unit on Ascension told The Telegraph.
He was transported to the United States for further treatment.
“I am OK and headed into surgery,” Matsu told Tracking Sharks.
A GoFundMe page has be set up to help Matsu with his medical bills.
This is the second bite on the island for 2017.
Frankie Gonsalves was snorkeling with her husband April 22, when a shark bit her leg and foot.
Her husband Dean swam to her aid and punched the shark, forcing it to release its grip.
She was treated on scene before being transported to the local hospital.
There have been a total of 61* shark attack bites in 2017, 5 of which were fatal*; 28 were reported in the US, with 20 occurring in Florida** and one in Hawaii. Nine occurred in Australia, one of which was fatal and one with no injury. Three unconfirmed worldwide and not included in the total count.
All locations have been marked on the2017 Shark Attack Bites Tracking Map.
*Two may be scavenge. **One report may have been outside of Florida waters.