Information on aquaculture in Portugal is in a state of flux as the Department of Fisheries has recently been absorbed by the Department of Agriculture, with different and often incompatible protocols for data collection and archiving. The information contained in this report is gathered from a number of different sources. Economic data by species for 1998 and 1999 were not available.

Aquaculture production of major species for the period 1990-2001is shown in Figure 1. Trout (mostly Rainbow) are grown in fresh water and have been omitted from this chart, but they are an important species, second only to clams in some years. Eels were an important product until 1994 (grown in both fresh and salt water), when they were worth as much as all other fish species combined, but they ceased to be economical because of the high cost of juveniles. Eel production currently is less than 1% of its peak value and is not shown in these charts.

The other finfish species are produced mostly in pens and land-based facilities. Offshore pen culture is being explored, and there are two large cages in deep water to the south of Portugal (the Algarve), but the rocky coast of Portugal is not well suited for fish farming.

As of 2000 there were 30 fresh water and 1,375 marine farms in Portugal, approximately the same number as in 1996. The marine installations were as follows (data from the National Institute of Statistics):

Most of these, especially the bottom culture sites, were in the Algarve, the southern province of Portugal. Except for the number of bottom culture sites, these figures all represent a decrease from 1996.

The value of aquaculture production is shown in Figure 2 (data for 1998 and 1999 are missing), and it is clear that clams are the most important product. So far as marine finfish are concerned, sea bream is the major species, followed by sea bass. Turbot is a relatively new species being farmed.

Fish farming is not growing rapidly in Portugal. The total production of farmed fish is shown in Figure 3 (both tonnage and value), and the increase is relatively modest. Most of the farming, especially of shellfish, is in the Algarve, and there is not a great deal of room for expansion as most of the farming is confined to the Ria Formosa region. Many farms are converted salt pans (salinas).

There is not much evidence of serious impact of marine aquaculture on the environment, although some farmed stocks have suffered from overcrowding – this has been a problem with clams. Since finfish are mostly farmed in pens rather than cages, there is little chance for disease exchange, and genetically modified species are not used so escapes are not an issue.

Much of the finfish farming is carried out in converted salt pans, or salinas (there are over 1000 ha of salinas still in use for production of sea salt). A typical system of salinas is shown in Figure 4, and the way in which they are used for fish farming is indicated in Figure 5. Water enters reservoir R at high tide and flows through the fish tanks F. The effluent goes into a settling tank S (this is required by law) before being released back into the marine environment.

There has been increasing interest in growing shellfish in the settling tank, which accomplishes the twin goals of growing shellfish in an environment with lots of food, and also removing labile carbon and nutrients from the effluent.

There is not a great deal of research on environmental interactions of mariculture, in large part due to the relatively low degree of impact expected. Most of the research is in the Algarve, where fish farming (especially shellfish) is largely centred, and there are several projects at the University of the Algarve.

Portugal is one of the partners in the AQCESS project (Aquaculture and coastal economic and social sustainability) led by the University of Aberdeen, and the site to be used for biological and socio-economic analysis has been selected as the Ria Formosa, in particular the town of Fuzeta. Maria Teresa Dinis is the chief scientist for this project. A Masters thesis (Diplome d’Études Superieures from the University of Bordeaux, France) by François Noel Hubert on "Effects of exposure to semi-intensive fish-farming effluents on the Ria Formosa lagoon system (Algarve, South Portugal)" was completed in December 2001 and concluded that there were some very localized effects near the outflows of semi-intensive ponds, but because of good water renewal in the Ria Formosa there were no significant far-field effects. This work was supervised by Sofia Gamito. A project in the Ria de Alvor in conjunction with Aqualvor resulted in a paper on the cultivation of Ulva rotundata in raceways using semi-intensive fishpond effluents by Rui Santos and Leonardo da Mata. Rui Santos is also investigating the Ria Formosa carbon production (both dissolved and particulate), and export/import dynamics through the inlets. All of these studies are being (or were) carried out at the University of the Algarve in Faro. Another project called SEAPURA (Species Diversification and Improvement of Aquatic Production in Seaweeds Purifying Effluents from Integrated Fish Farms, coordinated by the Alfred Wegener Institute for Polar and Marine Research in Germany) deals with the development of procedures and systems for cultivation of high-value seaweed species not used before in poly-aquaculture and investigation into providing some of the food for fish by re-using the seaweed biomass. This work involves Rui Santos along with Leonardo da Mata and Andreas Schünhoff at the University of the Algarve and Isabel Sousa Pinto along with Inês Domingues, Joana Matos and Rui Pereira at the University of Porto (Oporto).

Earlier work in the Sado estuary (near Setubal, south of Lisbon) by researchers at IPIMAR indicated that there were no serious chemical impacts from sea bream tanks, although some observed changes in plankton community structure suggested that expansion of fish farming in this region would require treatment of the effluents. The final report on this work was published in 2000 and there is no current work being done in this area.

IPIMAR is carrying on a project for the study of Aquaculture-Environment interactions in connection with clam production in Faro-Olhão lagoon, supervised by Manuela Falcão at CRIP-Sul. IPIMAR is currently constructing a large experimental facility for aquaculture research at the branch in Olhão (in the Algarve, near Faro), but so far only the hatchery component is ready. These facilities (both the land-based station and an off-shore fish cage) include studies of the impact of aquaculture on the environment in their objectives. IPIMAR has been monitoring the sea cage activity since its beginning, focusing on the  impact on bottom sediments and benthic communities.

Portugal has not encountered serious environmental problems associated with mariculture and therefore there has been only limited research in this area. The scale of mariculture is small, and Portuguese production figures are among the lowest in the EU. Given current practice – mostly land-based production of finfish, no use of special genetic strains, and relatively low production densities – the situation is not expected to change in the immediate future.