Fuel protests triggered by rising oil prices have spread to more countries across Europe, with thousands of fishermen on strike.
In Spain, Europe's largest fish producer, the action is expected to bring the industry to a halt.
Fishermen in France have been protesting for weeks, and their counterparts in Portugal, Belgium and Italy are also joining the campaign.
UK and Dutch lorry-drivers held similar protests earlier this week.
The strike reflects anger at the rising cost of fuel, with oil prices above $130 (83.40 euros; £65.80) a barrel.
Trade unions say the cost of diesel has become prohibitively high, after rising 300% over the past five years.
Wholesale fish prices, meanwhile, have been static for 20 years.
Map showing countries involved in protest
The European Commission has promised immediate help to restructure Europe's fishing industry, but it says subsidies to offset rising fuel costs would be illegal.
Burning tyres
Several thousand fishermen are expected to march on the agriculture ministry in Madrid, where they have promised to hand out 20 tonnes of fresh fish to members of the public in an attempt to draw attention to their ailing industry.
