Prime Minister Justin Trudeau has set the date for a byelection in an Ottawa riding left vacant by the death of Mauril Bélanger.

The byelection will be held April 3.

Bélanger held the long-standing Liberal seat for more than 20 years before his death in August 2016, months after being diagnosed with ALS.

The byelection is the first of five that will happen this year.

Trudeau has until the end of the month to set a byelection date in Calgary Heritage, which was former prime minister Stephen Harper's riding until his retirement last year, and until the end of March to set a byelection date in Calgary Midnapore, which Jason Kenney left to run for the leadership of the Alberta Progressive Conservatives.

By the summer, dates will also have to be set in the Toronto area riding of Markham-Thornhill, which longtime Liberal John McCallum left to become ambassador to China, and the Montreal riding of Saint-Laurent that Liberal Stéphane Dion held for two decades before leaving politics earlier this month to become ambassador to the European Union and Germany.