A special set of oceanographic elements makes the Portuguese mainland coast a giant wild metropolis, densely populated by marine life. The low temperatures, high salinity, availability of oxygen, and abundance of nutrients allow these waters to swarm with phytoplankton and zooplankton, the favorite prey of many pelagic fish like the Horse Mackerel (Trachurus trachurus), being the 3rd most caught species on the Portuguese coast, with catches stabilizing at around 10,000 MT per year.

Mackerels spend their life swimming in the cold, clear waters of the sea. Mackerels are migrating fish and so they move in large bunches depending on the weather. After spawning, the mackerels reach a stage called the "Autumn mackerel" when they are the fattiest and tastiest to consume and export to other countries.

As soon as the mackerels are caught from the sea, it is quickly cooled on board and brought to the shore. It is important that the catching areas are close to the shore because it enables the fisherman to go multiple trips when catching, which allows that fish to stay in its highest condition. Onboard, the fish are kept in a large holding tank with its own refrigeration that keeps the fish at a temperature of 0C at all times.