"We can't work; if it carries on like this we won't be able to eat," explains a Costa fisherman who can't leave port as all he is catching is a dense green seaweed. For months, boats using smaller nets in shallower water off Estepona and Marbella have been bringing up large quantities of a rapidly-growing variety of Asian origin, known as Rugulopterix okamurae.
"We've run out of places," says Manuel Haro, head of the Marbella fishing guild, "The algae was around San Pedro, towards the west, but it's now got as far as Cabopino, the only area that was still free of it."
Gradually more boats have stayed away, and now all 28 that use fishing techniques near the surface have been forced to stay in port in Marbella and over 20 more in Estepona.
The leader of the fishing community in Estepona, Pedro Benzal explained, "We're bored. We don't normally catch a single weed. But now its happening all the time and if the situation doesn't change, we will have to give up this style of fishing."
Haro explains that, unlike on land, there is no way to fumigate and remove the invading species. "If we carry on like this, the octopuses will move away and that fishing season starts in September. It could be a real problem as octopus is one of the things that keeps us going."
The extra worry is that the weed has been found at up to 200 metres depth, and if it reaches 300 metres, the larger dragnets of the bigger boats that fish locally will also start to be affected.
The regional and national governments are working together to find a solution to the seaweed, which is also affecting the sea off Cadiz province and building up on beaches along the coastline.