Illegal, unreported and unregulated fishing (IUU fishing for short) is one of the greatest threats to the sustainability of fishing, marine ecosystems, marine biodiversity, and human food security. Although international bodies and the UN regard illegal fishing as an environmental crime and the European Union has adopted a regulation to combat IUU fishing the problem has not been fully resolved because there are still gaps and loopholes.
Illegal, undocumented and unregulated fishing, also known as pirate fishing, has many facets. In deep-sea fishing, it is understood to mean all types of commercial fishing carried out without the necessary licence, in which the fishing quota authorised under the fishing licence is exceeded, or in which the quantities caught are not, not completely or incorrectly documented. However, it is also considered to be IUU fishing if a fishing vessel fishes in territorial waters of other nations without permission, or if it violates the fishing laws of that country, for example by ignoring fishing times and protected areas. The territorial waters of some West African countries, for example, are among the preferred fishing areas for pirate fishing. In none of these countries is there a strong fisheries control authority, so that the pirate vessels are not in much danger of being caught.