Cash-strapped Iceland began talks to join the EU in July, after the collapse of its banking system persuaded it to seek the financial security of European Union membership, a move opposed by the majority of its population.
The mackerel confrontation, which is upsetting Scottish and Irish fishermen who operate within quotas, "risks impacting negatively on the forthcoming accession negotiations between the EU and Iceland," EU Fisheries Commissioner Maria Damanaki wrote to Štefan Füle, the commissioner in charge of EU accession.
"There is no justification for the escalating levels of the Icelandic fishery," Damanaki is said to have written last month.
Scottish Fisheries Secretary Richard Lochhead said mackerel's reputation as one of the ocean's few sustainably-managed fish was now under threat.
"This issue transcends diplomatic relationships or regional rivalries because the very future and sustainability of global mackerel stocks is at stake," he said.
In response, the Federation of Icelandic Fishing Vessel Owners says Iceland has the right to fish as it wishes in its own waters, claiming to have only only raised its catch limits after unreasonable behaviour by the EU in fishing negotiations.
The incident sparks memories of the 'cod wars' of the 1970s, in which naval vessels and British and Icelandic trawlers clashed over access to then-bountiful cod stocks.
Climate change favouring Icelandic fleet
Warmer sea temperatures have caused migratory mackerel to swim further north than ever before, creating a valuable source of income for the Icelandic fisheries industry. Environmentalists expect such conflicts for resources to become increasingly common due to climate change.
Iceland is now permitting its fishermen to catch 130,000 tonnes of the silvery-blue fish, compared to a traditional catch that the EU estimates at 2,000 tonnes.
The Faroe Islands' catch has similarly increased, resulting in Scottish fishermen blockading a Faroese boat to prevent it from landing its catch in the Scottish port of Peterhead.
"The impact is huge, 90-95% of earnings derived from my fleet is derived from mackerel," said Ian Gatt, chief executive of the Scottish Pelagic (Oceanic) Fishermen's Association.
Ahead of future quota negotiations as part of membership negotiations with Iceland, the Commission has warned that this year's catch levels could be 20-40% higher than what is sustainable, calling the situation "anarchic".
Scotland's Lochhead agreed on Monday to work closely with Damanaki to pressure Iceland, claiming that "No options are off the table".
(EurActiv with Reuters.)
