FREEPORT, Maine — After a weekend on Maine roadways that saw four people killed in motorcycle crashes, statistics released Monday by state officials show that motorcycle fatalities in Maine are up dramatically this year.

Seventeen people died in motorcycle crashes in Maine between Jan. 1 and Aug. 3, 2015, according to a release from the Maine Department of Public Safety. That’s nearly three times the six motorcycle fatalities during the same period last year.

Eight people died in motorcycle crashes in 2013, 12 in 2012, seven in 2011 and 11 in 2010, according to the Bureau of Highway Safety.

Meanwhile, the number of motorcycle registrations has decreased, from 56,050 in 2011 to a high of 58,473 in 2013, and back down to 52,987 as of Monday, according to data from the Bureau of Motor Vehicles.

The causes of this weekend’s crashes remain under investigation, but two experienced riders said Monday that the greatest threat to motorcyclists on Maine roads comes from factors beyond their control.

“I think it’s obvious,” said Adam Asselin, 34, who works at L-A Harley-Davidson in Lewiston.

Asselin barely survived a 2011 crash in Turner.

“It’s the texting, the people driving cars not focusing, not noticing a motorcycle. With mine — I can’t remember the accident, but my good friend right behind me said the [other driver] admitted he was arguing with his wife, and when I went to make a left-hand turn, he just pulled right in front of me.”

“I ride pretty often, and I see so many people on cellphones,” said Mark Wild, 53, of Brunswick, who has ridden a motorcycle much of his life. “If you are distracted driving — it may be a cellphone, it may be a touch screen in a car — that is a potion for disaster for motorcyclists. It’s just making it even harder for them to be seen.”

Both riders acknowledged other factors, such as speed, alcohol, and not wearing a helmet, contribute to fatalities.

John Kohler, coordinator of the Motorcycle Safety Program for the Maine Bureau of Motor Vehicles, said Monday that in two decades of motorcycle safety work, “It’s been our experience that the majority of people involved in motorcycle fatalities did not have any hands-on motorcycle training.”

Without speaking specifically about any particular crash, Kohler said, “I’d be interested to know if any of these people had any hands-on training course under their belt … in multi-vehicle accidents, riders typically don’t have the skills to swerve or to apply maximum brake pressure without skidding. These are all the things the training course touches on.”

Kohler, who is the Maine state coordinator for the Motorcycle Safety Foundation, said alcohol, speed and the lack of a protective helmet also are important factors, which are all addressed in each of two Motorcycle Safety Foundation hands-on safety courses offered in Maine: a 15-hour course offered by training schools that includes 10 hours on a bike, and a five-hour experienced-rider course.

In an effort to reduce motorcycle fatalities, many training schools across the state will offer a free five-hour experienced-rider course the weekend of Aug. 22 and 23, Kohler said. The courses are funded by a grant from the Maine Bureau of Highway Safety. Many courses have already filled, he said.

“Our attitude is, once people have been riding for a number of years, they get complacent,” he said. “We’re trying to reach out to these people and say, ‘Come on in, hone your skills and maybe you’ll pick up something.’”

Asselin said that if drivers aren’t going to see him, he at least makes sure they hear him.

“When I’m passing someone, I’ll pull in the clutch a little bit and crack the pipes and give it some throttle — just so they know I’m there,” he said.

Wild said he and his wife, Susan Wild, “have had a few near misses” in 33 years of riding together, and are “always looking for what’s going to go wrong.”

His 18-year-old son also rides a motorcycle, but only after taking the safety course offered by the Motorcycle Safety Foundation.

“He’s a defensive driver,” Wild said. “[The course is] very effective.”