The Parti Quebecois is celebrating a by-election win in a south shore riding.

The riding of Vachon has been a PQ stronghold for the past 16 years, and political newcomer Martine Ouellet had no trouble holding on to the seat that was vacated in December by Camil Bouchard.

Premier Jean Charest "picked the worst time to hold an election, so we want to make sure the Parti Quebecois wins again," one voter told CTV News.

Opposition leader Pauline Marois said the by-election is a clear message to the government.

"We want Mr. Charest to launch an inquiry into the construction industry," said Marois, who said she will continue to push for an inquiry when the National Assembly resumes sitting in the fall.

The main issue in the region was increased traffic at the St. Hubert airport. While technically the noise is a municipal issue, many people who spoke to CTV said they were voting in hopes the MNA would be able to reduce the number of planes using the airfield.

Ouellet defeated Liberal candidate Simon-Pierre Diamond, who in 2007 ran for the ADQ, and at age 22 became the youngest person ever elected to the National Assembly.

Elections Quebec reported that voter turnout, typically low in by-elections, was about 30 percent.

"We had 20 percent earlier in the day," said one volunteer who frequently works at a polling station. "Normally it's 65 percent."