Portugal is located in a transition zone towards warmer ecosystems, which translates into a high diversity of fish but little abundance of each species. Although the sub-areas of the Azores and Madeira of the Exclusive Economic Zone are large, they have small fishing areas with shallow continental platforms, followed by high depths and some weaknesses at the biological level. These natural characteristics translate into a lower fish wealth compared to other Community fishing areas.

These factors determine the abundance of small pelagics and a considerable specific diversity, the abundance of which is determined by bathymetry, hydrological conditions and the nature of the bottoms, especially with regard to demersal species. In island regions, due to physical and biological constraints, catches are based on a very limited set of species, some of which are subject to migratory flows (such as tuna) or whose life cycle is not yet well known (black swordfish ).

The national fleet is predominantly composed of small vessels (about 91% with an overall length of less than 12 m) that operate with various gears such as gillnets and trammel nets, traps and longlines, in the most coastal area and, normally, up to 6 miles, this type of fishing is called multipurpose fishing. The other main fishing methods used are trawling, which catch horse mackerel, hake, monkfish, crustaceans and other demersals, and the purse seine, which fishes small pelagics.

In non-maritime inland waters (rivers, rivers, lagoons under the jurisdiction of the Marine Autority - Capitanias), some fisheries targeting migratory species such as shad, lamprey or eel are still relevant. In these areas, and also on the coast, marine animal harvesting activities are practiced, such as barnacles, mussels, donax clams, cockles and other bivalves, as well as fishing without the aid of a vessel (majoeiras, waist drag).

At the national level, the legal framework regulating the exercise of sea fishing and marine cultures in waters under Portuguese sovereignty and jurisdiction is regulated by Decree-Law No 278/87, of 7 July, with the changes introduced by Decree-Law Law No 383/98, of 27 November.