A Nova Scotia judge has granted a temporary injunction to stop fishermen from blocking survey boats hired to examine a route for a pulp mill's effluent pipeline.

Nova Scotia Supreme Court Justice Denise Boudreau decided the fishermen have the right to "lawful protest," but they don't have the legal right to block the survey vessels from doing their work.

Lawyers for the Northern Pulp mill in northern Nova Scotia argued that their project was being unlawfully held back by the fishermen's blockades.

Before the decision was handed down, about 80 people gathered outside the Halifax courthouse to protest the proposed pipeline that would pump treated waste directly into the Northumberland Strait near Abercrombie, N.S.

Kathy Cloutier, a spokesperson for Northern Pulp's parent company, Paper Excellence Canada, confirmed the mill was seeking an interim injunction to prevent blockades of the survey work in the Northumberland Strait.

A group of fishermen has stated they would block any survey boats from entering the strait.

The plan to pump treated effluent from its Abercrombie, N.S., mill into the strait has raised the ire of the fishermen, the P.E.I. government and even Hollywood actor Ellen Page, who is from Halifax.

Hundreds of boats joined a protest in July against Northern Pulp's proposed route for its effluent pipe. (Nic Meloney/CBC)

The wider Gulf of St. Lawrence fisheries region is home to lobster and crab fisheries that brought in over $1.2 billion worth of catch in 2016.

The Nova Scotia government has committed to stopping the flow of effluent to the heavily polluted Boat Harbour lagoon by Jan. 31, 2020. The lagoon is next to the Pictou Landing First Nation.

Outside the Halifax courtroom, the protesters carried signs that said "No pipe in the Strait," and they chanted "All I want for Christmas is no pipe."

Warren Francis, a 49-year-old fisherman and member of the Pictou Landing First Nation, said before the ruling was made that other protests would follow if an injunction is granted.

"I don't think it will stop us," he said. "My First Nation will have to step it up ... We don't want a pipeline in that strait ... I really hope it doesn't come down to violence."

Ben Chisholm, a 65-year-old business agent for the pipefitters union, said he came to the courthouse to support the mill's position because millions of dollars in economic activity could be lost if the mill closed.

"There's more support for keeping the mill open and cleaning it up than there is for closing it," he said, as the protest chants rang out nearby.

"Any time a big plant closes in an area, it's followed by poverty. There's nothing to replace this."