The waters of the St. Lawrence are vital to the livelihoods of the Innu, Mi'kmaq and Maliseet nations and should be protected, they told a news conference in Montreal as the Assembly of First Nations continued its annual meeting.
They also asked federal party leaders to tell voters ahead of this fall's election where they stand on the protection of the Gulf from development.
Mi'kmaq Chief Scott Martin said he feared an environmental catastrophe in the St. Lawrence similar to the 2010 Deepwater Horizon oil spill in the Gulf of Mexico that devastated parts of the southern U.S. coastline.
Martin added there are currently "numerous knowledge gaps" within oil-industry reports on risks associated with drilling along the waterway.
"The gulf is a highly productive body of water and diversity is very rich," he told reporters. "No one can tell us what effect a blowout like a Deepwater Horizon can have on the food chain."
Martin said he wants an "integrated assessment" of all the risks involved with resource exploitation in the area before Quebec grants exploration or drilling permits.
The chiefs said they decided the moratorium should last 12 years after calculating the time they thought it would take to conduct studies, write reports and consult the public.
Resource exploitation along the St. Lawrence River cannot be carried out without their consent, the chiefs said, adding the Supreme Court of Canada ruled native people must be consulted and accommodated before their territory can be used for commercial development.
Some chiefs were more hard line than others.
Innu Chief Jean-Charles Pietacho said his people won't be silenced with petrodollars.
"Never will I accept royalties that come from (the oil and gas sector)," he said.
Anne Archambault, grand chief of the Viger Maliseet First Nation, was more nuanced in her comments, saying she needed to consult her people before deciding on royalties.
She said her people's ancestral rights to the Atlantic salmon "take precedence over oil," adding 95 per cent of her community's revenue comes from the salmon industry.
Note to readers: This is a corrected version. A previous story had the word 'Jean' dropped in the first name of Jean-Charles Pietacho