Fishermen are being urged to stop dumping old equipment in Stornoway Harbour on Lewis, after 23 skips full of cables and debris were recovered.
Fishing cables were among the dumped items. Picture courtesy of Stornoway Port Authority
Stornoway Port Authority recently spent £20,000 dredging the harbour and found 50 tonnes of debris.
The port authority has been warned by the Scottish Executive about the high levels of pollutants found in sediment samples taken from the area.
It is seeking meetings with fishermen to resolve the issue.
Chief executive John Maclennan warned that the "extremely high levels" of polycyclic aromatic hydrocarbons found could result in the port authority being denied a licence for general dredging of the harbour to remove mud and sediment.
Oil is thought to be one of the pollution sources.
Mr Maclennan said: "Having spent in excess of £40,000 in plough dredging the anchorages in 2003, it is also most disappointing to see another 50 tonnes of trawl warps being recovered this year.
"The authority would remind all users that it is illegal to dump any waste material, including contaminated bilge water, at sea.
"It is in everyone's interests to clean up the harbour environment and we are urgently seeking meetings with all sections of harbour users to address these ongoing problems."
Oil from boats is thought to be one source of the pollution. Picture courtesy of Stornoway Port Authority
Mr Maclennan added that the debris was a hazard to boats using the harbour.
As well as the dredging operations, the port authority has been working with Comhairle nan Eilean Siar (Western Isles Council) in an ongoing weekly litter clearance in the harbour area.
This has resulted in the collection of 250 large bags full of litter since the project started in mid February - an average of 12 bags per week.
In the first week of the clean-up 172 blue rubber work gloves were collected and 65 bags of rubbish removed from the inner harbour area.
A spokesman for the Scottish Executive said: "It is illegal to dump anything at sea without a licence.
"Anyone witnessing any such illegal activity should contact their local Scottish Fisheries Protection Agency office."