Islanders who claim new conservation rules could put their economic future under threat are leading a protest at the Scottish Parliament.
Residents on Barra, in the Western Isles, say plans to designate some of their fishing grounds special areas of conservation will hit the industry.
Conservation agency Scottish Natural Heritage says sandbanks, reef and seal habitats need special protection.
Local MSP and government minister Alasdair Allan opposes the move.
For centuries, the fishermen of Barra have harvested the waters around their island and millions of people have become aware of the controversy because of the BBC series, Island Parish, which documents life in the southern Western Isles.
The protest by islanders will come as MSPs raise the issue during a backbench debate at Holyrood.
The Sound of Barra special area of conservation would also give protection, under European law, to species such as harbour seals.
Mr Allan, a junior education minister in the Scottish government, says the Barra community has been excluded from having a proper say on the issue and that generations of islanders have used the area responsibly.
The SNH consultation on the special designation has said fishing could continue on a managed basis, should the measure be put in place.
A Scottish government spokesman said: "Scottish Natural Heritage have carried out a substantial consultation on the designation of Barra.
"They are currently finalising their advice to ministers based on the consultation responses, and the Scottish government will make a decision once that advice has been considered in full."