the 11-time world surfing champion Kelly Slater announced his retirement to his one million followers on Instagram.

"Big decisions in life don't come easy and it's taken a lot of quiet time and personal introspection to come this conclusion," wrote the 43-year-old from Bells Beach, where he was computing at the Rip Curl Pro.

Twenty-two thousand fans tapped "like"; nearly two thousand were moved enough to write some kind of message, a litany of disbelief and wailing sadness.

 For so many years Kelly Slater has carried pro-surfing. But who picks up the mantle once he's gone? Photo: Association of Surfing Professionals
It wasn't a surprise. You could feel it; you could see it in his slumped shoulders and half-hearted turns as he struggled at the first event of the year, held in the dreariest surf imaginable. What dignity is there in losing to teenagers half your age and weight? What damage was being done to his immense legacy?

As far as retirement announcements go, this is one of the most profound, at least for the competitive structure that surrounds the sport. Professional surfing, you see, is a tenuous construction, despite its almost 40-year history.

Pro surfing began as the IPS (International Professional Surfers) in 1976, had a management change in 1982 whereupon its name was changed to the ASP (Association of Professional Surfers) and, then, this year, again under new management, shifted its title to the WSL or World Surf League.
Keeping it afloat has never been easy.

The Western Australian, Brodie Carr, who was CEO of the ASP from 2005 until 2011, says when he got the job, turned the key and looked at the files, "the ASP was insolvent. There was no repayment of debt. We were on the verge of extinction."

What kept it going, at least what kept enough mainstream interest in surfing to keep the sponsors coming, was America's Kelly Slater.

Because Kelly Slater wasn't just a simple dumb sportsman whose preternatural balance on a surfboard had given him such a hold on the sport for the last 25 years. Kelly Slater ticked every single box on a promoter's dream list.

He was handsome, he was articulate, he was fearless in big waves, dazzling in small waves, he dated movie stars and models but in such a way that it gave them dignity and didn't detract from his, he was interested in the environment, projected a magnificent health, rarely drank and never took drugs.
If it was based on his sporting performances alone, Kelly Slater would be the best sportsman who's ever lived. A career spanning 1991 until 2015, 11 world titles, and all gathered in one of the most difficult, and dangerous, sports on earth. A sportsman who has singlehandedly grown and kept alive an entire sport.

So what happens to pro surfing post-Slater?
It will lose its hub, its fulcrum, its measure of everything good, in and out of the water. There isn't another surfer, on tour, or off tour for that matter, who can speak with the authority of the entire game behind him. When Slater opens his mouth or taps his computer's keyboard, the surfing world shifts to his whim and his want.

For 25 years, professional surfing has been carried by this one single man.
And, today, he has retired.

Or has he? It may be April 2 in Australia but back in Slater's home country, it was April 1.
In a brisk email exchange, I wrote, "Yeah or non? Are you really done?"
"Non. F---ing gullible people, haha," he wrote.

As jokes go, it's a good one.
But it illustrates the danger of his retirement, which must come soon, if not this year, then next.
When Slater goes, so does professional surfing.