Back then Canada was antisemitic at large, and not just among the francophones. The McGill University in Montreal closed its entire pharmacology department because Jews would be several to attend it. When a boat full of German Jews fled Germany, it caused an uproar not only among francos, but also anglos. However the francos were more loud mouth, their speech and actions matched more, whereas the discrimination made by anglos was silent but institutional. Remember that back then, catholicism viewed the Jews as deicids : they would have voted to execute Jesus instead of the thief Barabas.

Quebec back then as no better than Francoist Spain and Salazar's Portugal in terms of how conservative its catholicism was. The clergy in Quebec back then would routinely bash the Jews, however it would never condone violences against them, it was a line they would not cross. Anything that was less than violence however was quite acceptable : banning the Jews from getting vacation houses in the Laurentides region, boycotting their shops, etc.

The Jews of Montréal back then were poor, with the exception of the rich anglicized Jews of the "uptown" (English downtown). They only spoke Yiddish and did menial jobs, just like most francos had no choice but to be exploited in menial jobs as well. This meant they occupied the same economical niche as the francophones, and therefore were direct competitors for the same jobs. Small alimentation businesses were one of the typical businesses the Jews had and unfortunately, it was directly competing with the same kind of businesses the francos has. They were therefore regarded as economic competitors.

A stereotype about the Jews of back then was that they were peddlers, and so they were regarded as annoying since they were trying to sell people stuff. They were regarded with the same disdain as the Jehovah's witnesses, that were also regarded as annoying due to their policy of door-to-door proselytism.

During the 1930's, a popular measure among the francos to answer the poverty of the times was the campaign of « Achat chez nous » (Buying in our own home), that was about buying exclusively from francophone businesses and boycotting anything that was not French, with the hope the money would stay among the francos instead of getting out. Although the Jews were a target of that boycott, they were not the only one. Anglo, Ukrainian, and basically anything that wasn't French were the targets of that campaign. The idea was that buying from non-francos would only enrich foreigners and never elevate the condition of the francos.

There was also a common prejudice that communism was a Jewish ideology, that somehow it was Jews that invented it. It's a misunderstanding based on a real fact : there was in Eastern Europe a segment of secular Jews that were pretty militant for the left, in parties called "bundist", and it is true that some bundists turned communist later. It was also true that Jews (cultural Jews, not pious Jews) were overrepresented among the communists of Montréal, as a consequence of having grown in the bundist culture. Since Quebec was very catholic, in a most conservative form of catholicism, being against the Jews was regarded as the same as being anticommunist. It is also true the only communist MP Quebec had, Fred Rose (Fishel Rosenberg) had a Jewish background, although he was not personally of Jewish faith.

Duplessis was a populist, demagogue politican and therefore he sometimes had these antisemitic rhetorics of the time, which were particularly useful because the few Jewish MP Québec had, like those of the famous Hart family that was well-rooted, always were in the opposing Liberal Party. Bashing the Jews was a way to also bash the liberals, that were regarded as collaborators with Jews. It was in essence electoralist. Duplessis would say the entire opposite when he would meet Jews. His predecessor in his party, Camillien Houde, was exactly the same, and would on one hand bash then and on the other praise them, depending on which public he spoke to. In short it was a rhetorics to get votes, but it was not an obsession they had in their decisions once in power. It was different from the actual fascists that couldn't sleep at night without thinking of the Jews and that were plotting their deportation to the James Bay. It was mean, petty perhaps, but not obsessional either.

As far as I know, once in the government, Duplessis didn't do anything different from his predecessors or from the federal anglos regarding the Jews. During his tenure, he actually used the resources of the state to persecute the Jehovah witnesses, more than the Jews in particular, unless you inderstand the persecution of the communists as targeting the Jews, which might make more sense with respect to their prejudices than with the reality (there were also francophone communists, think of Évariste Dubé for example).

It's worth mentioning the Jews of the 1930's in Quebec had very clever advocates like Caiserman that managed to build bridges and reduce the general ambiance of hostility by convincing the high clergy to censor the antisemitic speech in its media and organizing meetings with the Jesuits to explain what Jewish beliefs were really about, a religious dialog that was truly unprecedented in our history. There was even an organization initially aimed to convert Jews that turned into an anti-hate organization due to the influence of the new interreligious dialog that started to appear. Once the Jews finally realized the importance of having a good command of the French language and the mediatic context in French, they became able to make a much more effective lobbying. It became an habit among the Jews to have at least one spokeperson/interpreter that could speak French and it was effective in curbing the prejudices over time. As long as the Jews would only open up to the English-speaking society, it made them cut off from the French one. Once they realized the importance of maintaining a dialog with the French one, their situation improved.

The catholic clergy largely stopped bashing the Jews after Vatican II in 1962 and the hysteria about them gradually subdued after WW2. An entire Jewish enclave (Tosh) could form with impunity in Boisbriand (Sainte-Thérèse-Ouest back then) and no one would bat an eye any longer, while 20 years before there would have been a huge hysteria about it. In 1995, the Tosh even recommended to vote for the independence of Quebec, perhaps to not be alienated from their franco neighbours that lived all around them, as they lived in a region that was firmly for the YES.

Of all the immigrant groups in Quebec, the Jews is the best documented by the historians in Quebec, more than any other group. The Jews also have not one but two archive centres just for them. There is even a francophone historian, Pierre Actil, that studied Yiddish just to study them, so he could read their media like the Kanader Adler (Canadian Eagle).