Up to 30 fishing boats took part in a protest at Ballyglass Pier in Co Mayo relating to the construction of the Corrib Gas Pipeline.
The Erris Inshore Fisherman's Association are objecting to plans by Shell Ireland to locate a pipe that will discharge treated water into their fishing grounds in Broadhaven Bay.
They claim it would harm shellfish and other marine life in the bay.
The fishermen say the the laying of the pipe will also necessitate the removal of their equipment for the duration of the construction.
In their submission to the Environmental Protection Agency, the EIFA expressed concerns about about the effluent from outflow pipes associated with the project.
Shell have strongly disputed these claims.
