Mayor John Tory is calling on the federal government to tighten its gun laws, particularly those around how many guns licensed owners can amass.

Tory, who said he's been troubled by a rise in gun violence in Toronto this year, stated his case in a Dec. 15 letter to Public Safety Minister Ralph Goodale. There have been 37 shooting deaths in the city in 2016, according to police statistics — that's 12 more than there were in 2015.

Tory blames the spike in gun violence on the fact that there are more illegal firearms on the streets. Some 50 per cent of those guns are smuggled across the U.S. border, Tory said, while the other 50 per cent are domestic firearms making their way into criminal hands.

The mayor said there's an "obvious gap" in the government's oversight of those guns.

"What's particularly troubling to me is cases where certain licensed gun owners are able to amass small arsenals of handguns and that there are no red flags," Tory's letter said, noting the Canadian Firearms Registry tracks the sale of these firearms but not necessarily where they wind up.

"I was further shocked to learn that there is no limit on the number of firearms any one licensed gun owner can purchase and possess."

These guns, while acquired legally, are increasingly turning up in criminal investigations, according to the Tory. Police are even seeing criminals using long guns commonly sold to hunters.

In September, Canada's Commissioner of Firearms reported that the sale of restricted firearms — like semi-automatic rifles and handguns — shot up 9.5 per cent in 2015, and that since 2004 the number of those guns has doubled across the country.

Tory wants the federal government to come up with some way to further track or rein in weapon sales, though he said he realizes reinstating the long-gun registry may not be possible. He also called on police agencies to share more information when it comes to guns.