PORTLAND – The number of motorcycle fatalities hit the highest level in a decade in Maine in 2004, and riders who die are more likely to be baby boomers than teenagers on sport bikes, according to state officials.

The number of motorcycle deaths crept upward to 22, mirroring a national trend of more motorcycle registrations and more fatalities, said Carl Hallman, highway safety coordinator with the Maine Department of Public Safety.

Fourteen of the 22 deaths involved riders who were 35 or older. Overall, the 35-44 and 45-54 age groups each accounted for more deaths than young riders over the past five years, according to a report by the Bureau of Motor Vehicles.

At the same time, the number of motorcycle registrations has shot upward in Maine, from 27,650 in 1999 to 36,349 in 2003, according to state records. That’s a 31 percent rise.

A study by the National Highway Safety Administration said people killed on motorcycles are likely to be older and riding bigger motorcycles. Some have suggested that aging baby boomers with disposable income have played a role in the trend.

“That has some credence. It’s really kind of astonishing: The ages of these fatalities are so high,” Hallman said last week. “You would think it would be all of the young kids on those fast bikes, but it’s not. It’s the older generation.”

Hallman has computer records dating to 1994 for motorcycle crashes. The overall number of crashes has held steady between 400 and 500, but the number of fatal crashes has trended upward and reached 20 in 2003, he said.

Part of the reason older riders are being killed might be that some of them are deciding to hop on a bike for the first time in years.

In Maine, anyone who gets a motorcycle license holds the right to ride until they die. There are mandatory classes and clinics for new riders, but there’s no such requirement for a license holder who decides to get on a bike for the first time in decades.

“People have had licenses and haven’t ridden in 10 or 20 years. All of a sudden, they buy a big Harley. They’ve got to learn how to drive it,” Hallman said.

Steve Ireland, owner of Central Maine Motorcycle School, said he’s seeing an increase in the number of older riders seeking instruction.

“I’ve seen a lot of people getting back into the sport. They say, ‘I used to ride 20 to 25 years ago. I’m having a midlife [crisis]. I want to get back into it,”‘ said Ireland, who offered instruction to 200 riders in 2004.

Overall, 198 people, including the motorcyclists, died on public highways in Maine in 2004, said Stephen McCausland of the Maine Public Safety Department.

The number of highway deaths would have been closer to the record low of 169, but the toll was pushed higher by the motorcycle deaths, the Mother’s Day crash that killed seven in Carmel and the deaths of six all-terrain vehicle riders on public roads, he said.

The worst year for highway deaths was in 1970, when 276 people died on public roads in Maine, McCausland said.

Col. Craig Poulin, the state police chief, said his troopers are doing targeted enforcement on stretches of highway that are dangerous.