In the Baltic Sea alone, there is an estimated 1,000 kilometres of discarded fishing nets floating on the surface or deep below.
The nets catch and kill fish as well as marine mammals and birds that get tangled up in them. But there could be a solution to these so-called "ghost nets".
A group of environmental organisations concluded a conference on the EU-funded project Marelitt Baltic in Stockholm on Thursday.
The project involved coming up with solutions for dealing with discarded fishing nets, among them how to retrieve the nets and recycle them.