A new Canadian census that appears to show a significant decline in the number of Jews in Canada has experts divided over the significance of the figures.

Statistics culled from Canada’s 2006 “mini-census” released last week show that 315,000 Canadians identified themselves as Jewish by ethnic origin. This constitutes a 9 percent drop from 2001, when they numbered 348,000.

Canada’s largest Jewish populations are Toronto’s 141,685 Jews, Montreal’s 71,380 and Vancouver’s 21,465, according to the census.

As with past censuses, experts are divided over the significance of the numbers, with some saying the results are incomplete and skewed, and others arguing they are accurate.

Jim Torczyner, a professor of social work

at Montreal’s McGill University and a longtime interpreter of census results, says the latest figures are unreliable because they do not reflect what he says is a more significant marker of self-identification: religious affiliation.

“It’s not ethnicity alone that creates Jewish identity,” Torczyner said. “You can’t extrapolate [a decline] from a census that asks only about ethnicity when it comes to Jews.”

Canadian headcounts, held every decade in years ending in “1,” inquire about subjects’ religion and ethnic origins. Shorter mid-decade censuses, conducted in years ending in “6,” ask about ethnic background only. They permit respondents to list up to four ethnic origins, including “Canadian.”

Jews are the only group to fall into both categories, which has led to decades of communal debate over who and what constitutes a Jew.

The 2001 census found 330,000 Canadians who said they were Jewish by religion, an increase of 3.7 percent over 1991. About 348,000 listed their ethnic origin as Jewish, either alone or in combination with one or more other ethnicities, which was down by 1 percent from 1996.

Community officials combine the figures, excluding only those who say their ethnic roots are Jewish but also list another religion. There are about 50,000 in this category.

The community’s final official tally as of 2001 was 370,520 Jews in Canada.

In 2001, Jews ranked 17th overall among groups in Canada defined by ethnic origin, but in the 2006 census they ranked 25th.

Robert Brym, a sociology professor at the University of Toronto, said the latest numbers reveal a deeper issue, reflected in those who listed just one ethnic origin, Jewish, versus those who listed more than one, including Polish, Russian, Israeli and Canadian.

In 2006, he said, the number of people who identified with multiple ethnicities — on average, younger and more assimilated Jews — grew by a healthy 11.7 percent. But the number of single-ethnicity identifiers, who tend to be older and less-assimilated Jews, fell precipitously, by 27.6 percent.

Brym says the data show the older generation of less assimilated Jews dying off more quickly than the younger, more assimilated generation of Jews who can replace them.

He attributes this to low Jewish birthrates, the fact that Jews tend to be older than non-Jewish Canadians and the virtual end to Jewish immigration to Canada from places such as Russia and South Africa.

Torczyner interprets the data differently.

“When you give people a choice — when you can ask, ‘Are you Jewish by religion or ethnicity?’ — those who identify as Jewish by religion will then say they’re ethnically something else.”

Therefore, he said, “When you compare just the ethnicity numbers, you get a very confusing picture because you just don’t know whether some Jews are not responding at all.”