PORTUGAL

Western-most country of continental Europe, the Portuguese Republic occupies the Atlantic front of the Iberian Peninsula. A humid and mountainous northern half is separated from the dry southern lowlands by the valley of the Tejo, longest river of the Peninsula. Portugal's long sandy coastline is indented only by the estuaries of its large westerly flowing rivers, and lacks islands.

Moderately densely populated, it is primarily an agricultural and seafaring nation, marked by production of wine, olive oil, cork, other forest products and marine fish.

The country's water resources are among the poorest in Europe. Its rivers are subject to great variations in flow, many are polluted, and they receive heavy use especially in their lower reaches. It is almost lacking in freshwater lakes although possessing some large brackish lagoons.

Traditionally, there is great emphasis on oceanic fisheries, and there is high fish consumption per caput. The importance of inland fisheries, either commercially or recreationally, is, however, minor. Aquaculture, which is not a traditional practice, is still in its formative stages.

¹ In general, only continental Portugal is discussed here, although “Metropolitan Portugal” also includes the Azores and Madeira. The Azores are a group of nine major islands with an area of 2 247 km², situated 1 280 km west of the mainland. Madeira, with an area of 794 km², is 960 km to the southwest, off Africa. The two island groups had a combined population of 526 800 in 1988. The figures used here for areas and population are the official Portuguese figures (Portugal, Instituto Nacional de Estatística, 1989). The area of Continental Portugal as given here does not include that of the estuaries of the Tejo and Sado rivers and the Ría (or Lagoon) de Aveiro, totalling 404.2 km²

Portugal, situated between 42°9'8" and 36°57'39"N latitudes and 6°11'10" and 9"29'45"W longitudes occupies about 15 percent of the Iberian Peninsula. Seventy percent of the country is, in fact, the western slope of the ancient block, the Meseta, the Peninsula's central tableland. The remainder is the coastal plain which lies at its feet.

Roughly rectangular, its greatest length (N S) is 580 km, and its greatest breadth (F-W) is 225 km. Its altitudinal range is from sea level to 1 993 m. About 70 percent of its total area is less than 100 m in elevation, and less than 12 percent is over 700 m.

Portugal is bounded on the north and east by Spain for 1 215 km, and by the Atlantic Ocean on the west and south for 832 km².

² Length of boundaries from Portugal, Anuário Estatistíco… 1989 (Publ. 1989)

With respect to relief, and also climate, Portugal can be divided into two major areas separated by the southwesterly flowing Tejo (Tagus) River:

1. Northern Portugal. This is an area of rocky crystalline mountains and plateaux separated by narrow and deep river valleys with a general northeast-southwest trend. Most of the area exceeds 400 m, there are numerous serra 1 000 m or above, and the Serra da Estrela contains the highest mountains in the country. The highlands are primarily infertile schists, slates and granites, with mixed forest cover; the coastal forelands have low hills, swamps and dunes. Vineyards and small farms represent major land uses.

2. Southern Portugal. This is an area of rolling plains, low plateaux of sandstone and clays, and broad valleys. There are rare outcrops of hills and only one range over 1 000 m. Most of the area is below 200 m. Large-scale agriculture and grazing are dominant land uses as well as tree crops and marine fishing.

The 832-km coast of Portugal is generally low, level and straight except for river indentations where the best harbours are situated. The northern coast has a number of rocky bays or rías. The southern coast is fringed by lagoons and sandbanks.

With respect to plant cover, there is a mingling of Atlantic deciduous flora with Mediterranean evergreens. In general, there are three types of vegetation: (a) forests of oak, chestnut, and pine in the north and centre; (b) stands of cork oak and other evergreen oaks in the centre and south, and (c) dry, almost steppe like grasslands and evergreen brush or maquis in the south. Pines and eucalyptus are widely planted on the coastal plains.

There are two principal series of soils, each with little or no carbonate: (a) acid-humic soils covering most of the plateau area north of the Tejo, and (b) sandy or siallitic soils covering most of the rest of the country. In addition, there are calcareous soils in some areas, alluvial soils, and saline soils in the lower river areas. Less than 30 percent of the soils are well suited for agriculture.

4. CLIMATE

In the north, the climate is oceanic (cool summers and rainy winters) near the Atlantic, and continental (hot dry summers and hard winters) in the interior. In the extreme south, it is extra Mediterranean, with scanty rainfall, long hot summers, and even arid in some areas. The centre is a transitional area.

Mean temperatures in Portugal are about 4°C in January, 2°C in July, and 16°C annually. In the north it is about 6.2°C in January, 21.6°C in August, and 13.6°C annually. In the centre it is about 10.8°C in January, 22.5°C in August and 16.6°C annually. In the extreme south it is about 12.2°C in January, 24°C in August and 17.8°C annually.

The average annual rainfall in the country is about 865 mm. In the north, it is about 1 000 – 2 000 mm, and in the south about 400–800 mm. There is a marked seasonal distribution in precipitation which is similar for the entire country: a winter (November–March) maximum, and a summer (June-August) minimum.

Frost is almost unknown in the south. In the higher mountains, snow remains on the summits for several months between November and April.

5. HYDROGRAPHY AND LIMNOLOGY

Both the Portugal, Instituto Nacional de Estatística (Europa, 1985) and Table 4 indicate that the total inland water area of Portugal is only 440 km² or about 0.48 percent of the country's total area, an exceedingly small figure. It seems possible that reservoir, estuarial, and lagoon areas have been at least partly neglected in the calculation (see footnote one to section 1 and the footnote to section 7.1.1). An earlier statement concerning Portugal (Cotta, 1937, page 93) speaks of the “…92 000 ha of its rivers, streams, estuaries and bays.”

The average annual runoff from rainfall in Portugal is 224 mm or 20 000 million m³. An additional 17 000 million m³ is received from rivers originating in Spain, resulting in a total annual river discharge of 37 000 million m³ leaving the country (Van der Leeden, 1975).

The entire drainage is Atlantic, to which all the major rivers flow in a generally westerly direction.

5.1 Rivers (Rios)

North of the Tejo, most Portuguese rivers flow northeast-southwest in narrow gorges. South of the Tejo, most rivers flow southeast-northwest through broad valleys. The Guadiana which turns southerly in its lower course is a marked exception.

There are 11 independent river systems in Portugal where the length of the main river within the country exceeds 60 km. The size of their basins and their extent within the country as well as their navigable length and mean annual flow are shown in Table 1. Total basin size as well as average monthly and annual flows of the three major international rivers (Douro, Tejo and Guadiana) and the Mondego are shown in Table 2.

The flows in Portuguese rivers are extremely irregular, with the ratio between minimum and maximum discharges 1 to 8 or 1 to 10 for northern rivers and 1 to 40 for southern and eastern rivers. In the winter, great floods occur and vast amounts of silt are carried downstream. Some rivers dry up almost completely in summer. The regime is very rapid in the hills but slow and sluggish nearer the coast. The major Portuguese rivers, from north to south, are described below.

The most northerly river of Portugal is the Minho which originates in Spain (as the Miño) and forms a boundary stream for 75 km before entering the Atlantic at the end of its 338-km journey. Although it flows through deep and precipitous gorges, it is navigable in its lower reaches.

The Lima also originates in Spain (as the Limia or Antela). With a total length of 112 km, it runs for 65 km in Portugal of which 3.2 km is a border with Spain. See especially Valente (1990) for an account of the fishery in the Lima.

South of the Lima are two rivers confined to Portugal: the Cávado (118 km) and next the Ave (85 km) with navigation only near their mouths.

The Douro, with a total length of 895 km of which 322 km are in Portugal, originates in northcentral Spain as the Duero and flows generally westward to the Portuguese border. Here it forms a boundary of 126 km and then crosses the country to enter the Atlantic just south of Porto. Relatively even in mid-course, both its upper and lower reaches cut through gorges. Although the lower 200 km are navigable, they are subject to flood, and cataracts impede travel. Tributaries in Portugal which are shared with Spain are the Agueda (left) and Tâmega (right). In addition to its use for navigation (including transport of Port wine) the Douro is used for irrigation and production of hydroelectric power.

South of the Douro is the Vouga River, rising in the Serra da Lapa of north-central Portugal, and flowing for 136 km to the Atlantic through the 64.2-km lagoon complex, the Ría de Aveiro.

To its south is an even larger river, the Mondego, the longest river (220 km) flowing entirely within the confines of Portugal. Although subject to flash floods, it is navigable for 85 km.

Bisecting the country is the Tejo (Tajo in Spanish, Tagus in English) River of the lberian Peninsula. Rising in east-central Spain, it has a total length of about 1 007 km of which 275 km are in Portugal. It is a boundary stream between the countries for about 47 km. Navigation begins above the mouth of its largest tributary, the 210-km right bank affluent the Zêzere, and continues downstream for 212 km to where it expands into a tidal lake or estuary, the 240-km² Mar da Palha, the great harbour of Lisbon.

Table 1

Hydrologic data on the principal rivers of Portugal^a

^a All with respect to Portuguese territory

Source: Portugal, Instituto Nacional de Estatística (1984) and (1989) after Instituto Geográfico e Cadastral e Direcção-Geral dos Recursos e Aproveitamentos Hidráulicos.

Table 2

Discharge of four major rivers in Portugal

Source: Van der Leeden (1975) after Unesco (1971)

South of the Tejo, the first rivers of importance are the 175-km Sado with an estuary of 100 km² and the 130-km Mira. Flows are often low in both streams.

Last of the major rivers of Portugal is another international water, the Guadiana. With a total length of about 778 km from its source in Spain to its mouth in the Gulf of Cadiz, it flows for 260 km in Portugal, forming a boundary with Spain for 112 km of this course.

5.2 Lakes (Lagos)

Portugal is generally deficient in natural freshwater lakes. There are some small trout lakes (really reservoir) in the granitic Serra da Estrêla in the north.

5.3 Reservoirs (Barragem)

There are a considerable number of impoundments in Portugal for production of hydroelectric power and to assist irrigation. Among the large reservoirs or barrages are the: Paradela, Salamonde, Caniçada, Alto Rabagão and Venda Nova in the Cávado river drainage; Castelo do Bode, Bouçã and Cabril on the Zêzere; ldanha-a-Nova on the Ponsul; Aguieira and Raiva in the river Mondego; Crestuma, Carrapatelo, Régua, Valeira, Pocinho, Bemposta, Picote and Miranda on the Douro; Montargil in the Sorraia drainage; Maranhão on the Seda; Pego do Altar, Campilhas, Vale do Gaio and Odivelas in the Sado drainage; and Santa Clara on the Mira.

The morphometry of three of these reservoirs is shown in Table 3. These three warm monomictic reservoirs lie in a granite region in the north of Portugal. Maximum surface water temperatures attain 22°C in August and the minimum of 7–9°C is reached in February. They are all well oxygenated, have extremely low alkalinity and hardness, have a pH close to neutrality, and have a poor nutrient level. All have salmonid populations (Oliveira, et al., 1985). Portugal has over 20 of the highest dams in the world.

Table 3

Morphometry of three Portuguese reservoirs

Source: Oliveira et al. (1985)

5.4 Lagoons

There are a number of great lagoons along the coast, cut off from the sea by sandbars. Among these is the lagoon-canal complex of Aveiro (64 km²) in the delta of the Vouga River, and Albuffeira, a brackish lake south of the Tejo near Sesimura. (See section 7.2.)

6. LAND AND WATER USE

Portugal, only about 37 percent urban and about 63 percent rural, has few natural resources. It is largely an agricultural country, although its yields are the poorest in Western Europe. Cereals, potatoes, olive oil, wine grapes, and fruit are principal crops. Livestock is of minor importance. Although rice has been grown in Portugal for about 700 years, the paddies have not been used for fish culture.

Most of the rivers flow in narrow valleys with floors far below the surface of the surrounding flatlands making it difficult to lift water for irrigation without impoundment. Hence, despite needs for irrigation especially in the south, where the dry season may last for four months of the year, it was not well developed for many years. Furthermore, the heavier precipitation in Portugal has not made irrigation as imperative a need as in neighbouring Spain. In recent years, however, irrigation has been emphasized, many schemes involving large impoundments have been developed, and in 1986 almost 7 percent of the country was irrigated. Fertilization is very low, however.

Much of Portugal is better suited for forestry than for agriculture, and some agricultural lands may be taken out of production. Although Portugal ranks only about fourteenth in European forest production, it leads the world as a producer of cork oaks. It also places emphasis on planting pines and eucalyptus.

Table 4

Pattern of land use in Portugal, 1986

Source: 1987 FAO Prod. Yearb., 41 (Publ. 1988)

Only moderately rich in minerals, Portugal produces tin, wolframite, iron, uranium, copper pyrites, stone, and some coal. Most mining is concentrated in the north and minerals are not greatly exploited. Deficient in hydrocarbons, most of its fuels have to be imported. Sea salt is extracted from estuaries and lagoons.

Until 1945, only one third of Portugal's power was derived from hydroelectric plants, but following a national plan of 1944, it has now been developed extensively. Many dams have been constructed on streams such as the Lima, Cávado, Douro, Mondego, Tejo, Zêzere, Ponsul and Sado. Development was slow until such impoundment, because even with good fall in the northern streams, their volume of flow was quite irregular. Hydroelectric impoundment is often combined with that for irrigation. In 1987, of a total installed capacity of 6 851 000 kW, hydroelectric power represented 46 percent (3 173 000 kW). The other 54 percent was thermal with most of its fuel imported. Most of the hydroelectric potentialities have now been achieved, the country is switching most of its generating capacity from oil to coal. Nuclear stations are not planned at this time.

Industrial development has been slow in Portugal, especially due to shortages of minerals and power, and has been primarily designed for home markets. Essentially light, it is concentrated on textiles, food processing (e.g., sardines, olive oil), wine, cement, chemicals, metals, domestic crafts, and small workshops. Major industries are concentrated in western and coastal areas such as the Porto Aveiro-Braga and Lisbon-Setubal areas, and most people live in centres with less than 2 000–3 000 inhabitants.

Systems of rail (3 588 km in 1986) and road transport are generally sufficient for the country's economy. On a European scale, road density is actually not high (only 0.22 km/km² in 1987). Futhermore, roads are often lacking along the higher river valleys and their deep narrow gorges. Private automobile ownership is low (166 per 1 000 in 1986), on the continent there is not much travel by the ordinary individual. There is navigation for small craft on a number of rivers (see Table 1).

There are good ground water supplies in Portugal, but river water is also used for domestic use, and supplies over 80 percent of all needs. With respect to overall water use Portugal is one of the few countries in Europe where agricultural use exceeds industrial use.¹

¹ The others are Cyprus, Greece, Hungary, Malta and Spain

Marine fisheries, together with agriculture and forestry, have long been mainstays of traditional Portuguese economy. They are fairly large, diversified, and include distant water fisheries. Overall, their contribution to the GNP (1978) was only about one percent, but their relative importance to the country was higher because fish products represent about 40 percent of the protein available to the population, and the per caput consumption of fish is around 40 kg annually (FAO, 1978).

Tourism is an important industry in this picturesque country (16 million tourists in 1988), but attraction of tourists through inland fisheries is small.

7. FISH AND FISHERIES

The fish fauna of Portugal's inland waters, like that of Spain, is rather limited. Almaca (1965) lists only 33 species, including those which are introduced and some which are euryhaline. Portugal/EIFAC (1991) says there are about 43 species. Among the native fishes of importance are: lampreys (Petromyzonidae), sturgeon (Acipenser sturio), European eel (Anguilla anguilla), Allis shad (Alosa alosa), Twaite shad (A. fallax), brown trout (Salmo trutta), barbels (Barbus spp.), bogas (Chondrostoma spp.), chub (Leuciscus cephalus), ruivacas (Rutilus spp.), tench (Tinca tinca), and grey mullets (Mugil spp.). Introduced fishes include: rainbow trout (Oncorhynchus mykiss), common carp (Cyprinus carpio), goldfish (Carassius auratus), pike (Esox lucius), and largemouth black bass (Micropterus salmoides). The crayfishes, Procambarus clarkii and Astacus pallidus, are also to be found in Portugal.

The Atlantic salmon (Salmo salar) is reported (Netboy, 1980) to have once ranged as far south as the Tejo, and Schwiebert (1975) states that the Douro's salmon runs once rivalled those of the Rhine but were eradicated in the early part of the nineteenth century. It is generally considered that the Minho now constitutes the southernmost limit of this species in Europe and Ernest Schwiebert (in a personal conversation with the author in 1980) verifies this statement. However, Valente (1990) describes a small present day run of salmon in the Lima, and Muus and Dahlström (1975) say that salmon enter the Ave River sporadically.

7.1 Capture Fisheries

Fifty years ago, it was reported with respect to Portugal, that “Inland waters are fished almost to exhaustion while in many maritime districts farmers have one foot in sea and one on shore” (Great Britain, Naval Intelligence Division, 1942). This account went on to say that the freshwater fisheries were mainly confined to north and central Portugal as the rivers of the south were few and small. Stream fishes included trout, barbels, and boga (Chondrostoma). Overfishing had seriously depleted the stocks in many of the more famous trout rivers: Cávado, Mondego, and Zêzere. Trout were said to be also found in the Minho and other northern mountain streams.

With respect to other inland species, it was stated that lampreys, eel, shad, salmon, mullet and “sole (Solho-rei)” visited the rivers periodically. The “Solho-rei” was probably a sturgeon (Acipenser) which is in danger of extinction today and confined to the Douro and Guadiana rivers.

The freshwater catch in 1934, shown in Table 5, was said to represent 1.5 percent of the total Portuguese fish catch for that year.

Shad was considered to be the most important freshwater fish. Running in the Tejo and the lower reaches of the northern rivers, they were caught at the mouths of rivers with seines. Fishing areas included the Minho for lampreys, eel, sea trout, salmon, mullet, the mouths of the Douro and Guadiana for “sole”, and the Ría de Aveiro for lamprey, eel, shad and “sole”. Even at that time (1934–42), the Minho was said to be the only salmon stream in Portugal with a catch of 300–400 fish/year.

The picture of capture fisheries in more recent years is presented in the section below.

Table 5

Freshwater catch in Portugal, 1934

Source: Great Britain, Naval Intelligence Division (1942)

7.1.1 Commercial fishing

Table 6 which shows the catch in the inland waters of Portugal for the period 1965–87 as reported by the Government to FAO, illustrates the difficulty of obtaining useful catch statistics from the standard sources. Inclusion by FAO of the six species groups in its statistics indicates that there was at least some catch in inland waters of all of these fishes during the 1965–87 period. But the exclusion from the inland catch statistics of most of these groups after 1969 through 1977 is puzzling. Note, however, that in the Portuguese statistics for catches in the Northeast Atlantic (second section of Table 6), measurable catches of five of the same species-groups are recorded in most years of the 1974–87 period, and the same five groups are at least represented in the marine table from 1970 on, although not for the 1965–69 period. One can speculate, therefore, that fish caught in Portugal's estuaries may have been formerly recorded as “inland water” catch but were later placed in the marine statistics.¹

¹ In support of this supposition, one notes that the FAO Yearbook of Fishery Statistics, Vol. 36, for the period 1970–73 lists the catch of the two shads under inland waters and not under marine waters as shown in Table 6. (I have not used this volume for catches after 1969 (1970–73) as FISHDAB is more accurate.) It should also be noted that in the current system of designating the area of continental Portugal (see section 1), the estuaries of the Tejo and Sado rivers and the Ría de Aveiro are not included. In other words, these now seem to be considered marine waters

Lopes (1986) states that no valid statistics exist in Portugal for any commercial inland fishing, although there were (circa 1986) about 3 000 fishing licenses for inland commercial fishermen. Portugal/EIFAC (1991) corroborates the first statement. It is obvious that commercial fishing in Portugal's inland waters is now of minor importance, and is probably largely confined to estuaries. For example, although some eel are caught in rice culture irrigation channels, most of the eel fishing is carried out in the estuaries of the larger rivers.

7.1.2 Sport fishing

There is little published information on sport fishing in inland waters of Portugal. Popular books on the country (e.g., Campbell, 1957; Bridge and Lowndes, 1967; Lowndes and Moore, 1978) indicate that there is trout fishing in rivers like the Minho and Lima, smaller northern streams, and the lakes of the Serra da Estrêla, as well as angling for eel, cyprinids and lagoon fishes.

Table 6

Nominal catches by species in the inland waters of Portugal 1965–87 (in tons)

Nominal catch of freshwater and diadromous fishes in the Marine
Statistical Fishing Area 27 (Northeast Atlantic) by Portugal, 1965–87 (in tons)

- This category not listed this year
... Not available
0 Probably nil, negligible or insignificant; or less than 50 t during the 1965–87 period, or less than half a ton during later years

Source:   1965–69 Yearb.Fish.Stat.FAO, 36 (Publ. 1974)
1970–83 FAO Fish.Dept.Fishery Statistical Div. (FISHDAB)
1984–87 Yearb.Fish.Stat.FAO, 64 (Publ. 1989)

A booklet issued by the Portuguese National Tourist Office (Schmidt-Luchs, ca 1982) lists five species groups as providing freshwater sport fishing in continental Portugal. It describes barbel as found in all Portuguese rivers and streams, and common carp as found in most rivers in the centre and south. Largemouth black bass fishing is listed for various reservoirs and rivers in the centre and south. Trout localities are given as streams from the Alge to the north, as well as lakes of the Serra da Estrela. Shad are listed as being taken on artificial lures in fresh water during the spring and early summer.

Lopes (1986) states that there were about 80 000 sport fishing licenses issued in Portugal circa 1986, but that there are no valid statistics for sport fish catch.

Both rainbow and brown trout, largemouth blackbass, tench and carp are stocked by the state in small quantities to provide sport fishing. (See section 7.2 below.)

7.2 Aquaculture

The culture of fish for food, is a recent development in Portugal. About 250 t of trout, mostly rainbow, were produced annually circa 1977 (Brown, 1983), the total production (by five private trout farms) had risen to 900 t by 1984, and to about 1 000 t (by six private farms) in 1985. The annual production remains at about 1 000 t today. The fish are reared in concrete raceways, silos, or cages, and fed on pelletized food. They are harvested at a size of 200–250 g and sold to domestic fish markets and restaurants. Average production time for trout in Portugal is 12–15 months. It is believed that all or most of the present production is absorbed by the internal market, although some years ago, trout from some of the southern areas were sold for export. The General Direction of Forests has also sold some trout for consumption, but its primary production of trout is for stocking northern streams and reservoirs. In 1990, about one million trout were produced for this purpose.

Some farms also rear eels, with a total estimated production of about 1 280 t today.

Recently, a new Atlantic salmon farm was installed with an estimated return of about 625 t annually.

A new private farm is producing cyprinid fingerlings for ornamental purposes with an estimated production of 6 720 000 annually.

The source of most of the information given above is from Lopes (1986) and Portugal/EIFAC (1991). Somewhat different inland water aquacultural production data for Portugal taken from FAO, Info., Data and Stat.Serv. (1990, 1991) follows (in tons):

Only a few lagoons or marshlands appear to be sufficiently sheltered or otherwise possess requisite qualities for brackishwater aquaculture. Barahona-Fernandes (1981) discusses the possibilities of combining salt production and coastal aquaculture, citing the following areas as favourable for coastal aquaculture: the embayment of Mondêgo, the estuarial-lagoons of Aveiro, Tejo, Sado and Alvôr and the Faro-Olhäo lagoon complex. Under the Plano Nacional des Pescas, an extensive programme for fish farming, in 1985 there were 31 State authorized fish farm sites mainly on the Sado estuary and in the Algarve according to Fish Farm.Inter., 12(4) (1985). Fishes mentioned as suitable include: European eel, shad, grey mullets, gilthead (Sparus aurata), sea bass (Dicentrarchus labrax), and flatfishes.

8. OWNERSHIP, ADMINISTRATION, MANAGEMENT, INVESTIGATION AND AGREEMENTS

8.1 Ownership

Commercial fishing and aquaculture are private activities in Portugal. However, there are three state owned industrial units in the north producing trout for retail.

8.2 Administration

The Ministry of Agriculture, Fisheries and Food has overall responsibility for inland fisheries in Portugal, under the jurisdiction of the General Direction of Forests (Direcção-Geral das Florestas).

Administrative services conducted by the General Direction of Forests consist of:

1. Central Services: Hunting, Apiculture, and Inland Fisheries Service;

2. Regional Services: Six Forest Circunscriptions;

3. Local Services: Forest Administrations dependent upon the respective Regional Services.

8.3 Investigative and Scientific Services

1. Instituto Superior de Agronomia, in Lisbon conducts courses that include subjects in fisheries and aquaculture;

2. Faculdade de Ciências de Lisboa (University of Lisbon) conducts courses in biological sciences;

3. Faculdade de Ciências de Coimbra, conducts courses in biological sciences;

4. Faculdade de Ciências do Porto, conducts courses in biological sciences and research in aquaculture, population dynamics and fish diseases;

5. Instituto de Ciências Biomédicas Abel Salazar, in Porto, conducts courses and research in aquaculture;

6. Universidade de Trás-os-Montes e Alto-Douro, in Vila Real, conducts courses of zootechnics and research on pelleted fish food, reproduction in fish farms and primary productivity;

7. Estação Florestal Nacional, in Lisbon, conducts general research on inland waters;

8. Laboratório Nacional de Investigação Veterinária, in Lisbon, concerned with research on fish diseases.

8.4 Other Concerned Agencies

1. The General Direction of Natural Resources (Direção-Geral dos Recursos Naturais), which, with regard to inland fisheries, approves the installation of industries which discharge effluents into inland waters and controls water quality;

2. Parks, Reserves and Nature Conservation Service (Serviço Nacional de Parques, Reservas e Conservação da Natureza).

8.5 International Agreements

Portugal has a bilateral agreement with Spain concerning uses of their boundary or international streams with respect to hydropower, water supply, and water quality.

9. STATE OF THE FISHERY

9.1 Yield

The rounding of numbers in the earlier statistics reported by FAO and doubts of their validity make it impossible to infer any real trends in the catch from Portugal's inland waters shown in Table 6. One can only say that the reported catches are among the lowest from reporting European countries. These and future statistics require considerable revision before they can indicate the state of exploitation and maintenance of the fishery.

9.2 Factors Affecting the Fishery

The hydrography and climate of Portugal provide good keys to the present and future of its inland fisheries. Its mountain streams of steep gradient and rapid flow cannot provide large populations of fish, and even lower streams which fluctuate widely in volume, carry large amounts of silt, and go nearly dry in summer, do not provide good fish habitat. “It is probable that the degree of flow variation is as great as anywhere in the world” (Key, 1956). Furthermore, the general rock and soil types in Portugal are not indicative of potential high productivity. It can also be noted that the gorge-like character of many streams makes access for fishing difficult.

Lakes are so few in number and small in size that they can support only small fisheries. Lagoons do not appear to have as much use for fisheries as is accorded in other southern European countries. Reservoirs are used both for commercial and sport fishing throughout the country and are utilized for cage culture in some northern areas.

Unfortunately, water pollution is a major problem in Portugal. All of the major rivers are polluted with domestic and industrial wastes, often of high organic content. Many of the small streams which flow through inhabited areas tend to become toxic during the summer months simply because their flow is inadequate to provide sufficient diluting power. Furthermore, sudden surface water pollution which comes with the rain following drought adds to the problem. Effluents from paper and pulp factories, distilleries and plants for recovery of vegetable oils, tanneries, food processing plants, chemical factories, and other industries are rarely treated. It has been stated (Holden and Lloyd, 1972) that treatment of effluents from small olive oil producers and distillers is reported as simply too costly for the industry to bear. Nevertheless, laws for pollution control are being promulgated.

In addition, some rivers have been completely sterilized by mining wastes. Furthermore, the largest rivers of the country originate in Spain and thus transport the effluents of that country into Portugal. Nevertheless, in contrast to the situation in much of Europe, Portugal's oligotrophic lakes are high in the mountains in non-agricultural areas thus escaping eutrophication from agricultural chemicals. At present, Portugal uses very little fertilizer. In 1973, Spain used 20 percent more per hectare, Greece and Italy almost twice as much, France 4.4 times as much, and the Netherlands ten times as much (Baytelman, 1979).

In estimating the extent to which water quality can be maintained through fluvial dilution, one notes that the average runoff per caput in continental Portugal from all sources is 3 784 m³ annually, although only 2 045 m³ annually from rainfall confined to the country.

Anadromous fisheries, particularly for Atlantic salmon, have been borderline for years. The construction of barrages on rivers as well as water pollution has affected them adversely.

Lastly, the use of inland fisheries either for commerce or as sport has not been a tradition in Portugal as in many other European countries. There has been some effort to promote angling by tourists (especially for big-game species) in Portugal's marine waters, but little with respect to freshwater species until lately.

9.3 Prospect

Further development of capture fisheries cannot be anticipated except in areas not subject to water diminishment and pollution. Possibly, better management of mountain streams will improve sport fishing as will multiple use of Portugal's reservoirs. It is anticipated that Portugal will more than double its reservoir capacity by 2000 (ECE, 1978). Aquaculture in fresh and brackish waters offers some opportunity.

10. REFERENCES

Almaça, C., 1965. Contribution à la connaissance des poissons des eaux intérieures du Portugal. Rev.Faculd.Cienc.Lisboa, 2, Série -C-Vol. XIII-Fasc.2°, pp. 225–62

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