(CNN)The world of surfing is mourning the death of John Shimooka at the age of 51.
Shimooka, a former world tour surfer turned broadcaster, died in the early hours of Monday morning, according to Surfing NSW, for whom Shimooka had been general manager of partnerships since 2018.
"He will be remembered for his passion for the lifestyle as well as his energy and enthusiasm," said a statement from Surfing NSW.
"Everyone in our organization joins his son, Brandon, immediate family, and his extended worldwide network of friends, in grieving his loss. It is our saddest day.
"We will commemorate and celebrate John's life in the days and weeks to come."
At about 1am on Monday, police were called to a home in Sylvania, a southern suburb of Sydney, due to concerns for the welfare of a man, a NSW Police spokesperson said in response to a query from CNN.
"On arrival officers located a man unconscious inside the home. The officers rendered first aid before NSW Ambulance paramedics took over, but he died at the scene," the spokesperson said.
"At this stage there doesn't appear to be any suspicious circumstances. A report will be prepared for information of the coroner."
In a statement, the World Surf League, the sport's global governing body, said it is "saddened to learn of the passing of John Shimooka. A former CT (Championship Tour) surfer, industry executive, commentator and coach, he made a major impact on the surfing world. Our hearts are with his family and friends."
Originally from Hawaii, Shimooka, who also had a black belt in jiu-jitsu, competed in the World Surf League's men's Championship Tour between 1989 and 1998.
Kelly Slater, an 11-time world surfing champion, paid tribute to Shimooka on Instagram, saying: "My heart's ripped out. I'm sorry, Shmoo. I thought we had this."
Another former world champion, Tom Carroll, replied to Slater's post with the words "no-sense. I thought so too. Shmoo RIP," while four-time world champion Lisa Andersen commented on Shimooka's most recent Instagram post: "I'm lost for words. Hope you are at peace."