Biological Conservation 72 (1995) 125-127 © 1995 Elsevier Science Limited

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FRESHWATER FISH A N D THEIR CONSERVATION IN PORTUGAL

Carlos Almaga Museu Bocage, Departamento de Zoologia e Antropologia, and Centro de Fauna Portuguesa, Faculdade de Ci~ncias,

Rua da Escola PolitOcnica, 1200 Lisboa, Portugal

Abstract There are 36 species and subspecies of freshwater fish and three migratory species in Portugal. Eleven have been introduced, 13 are endemic to the Iberian Peninsula and two live exclusively in Portugal (Chondrostoma lusitan- icum and Rutilus macrolepidotus). Industrial pollution and the introduction of exotic fish species are the most serious conservation problems for Portuguese endemic fish.

Keywords: endemic, fish, conservation, Portugal.

INTRODUCTION

Portuguese freshwater fish and migratory species enter- ing inland waters in Portugal are listed in Appendix 1. Introduced species are also included. Most of the strictly freshwater species living in Portugal are endemics from the biogeographic unit of the Iberian peninsula. These species will be considered in detail below.

Conservation of inland fish in Portugal is now a seri- ous problem. The main factors related to freshwater conservation are also considered below.

ICHTHYOGEOGRAPHY AND BIOCLIMATES

The Iberian peninsula lies in the Mediterranean Subregion of the Holarctic. Owing to pre-Pliocene land connections with northwestern Africa, its flora and fauna present a special pattern in Europe for which the term 'Lusitanian' has long been used (Scharff, 1899; de Beaufort, 1951), and has been retained for the particular biogeographic District that Iberia forms within the Mediterranean Subregion.

The species distribution of the main component of its inland freshwater fauna, the Cyprinidae, enables three subdistricts or sectors to be identified within the Lusita- nian District (Almaqa, 1978): the Ebro-Cantabrian, the Central and the Southern. The first sector lies entirely within Spain, whereas the Central (Douro, Tejo and Sado basins) and Southern (Guadalquivir, Guadiana and Mira basins) Sectors are shared by Portugal and Spain.

The distribution of natural vegetation in Portugal reveals a transition between Mediterranean and Atlantic bioclimates. Four different vegetation zones can be distinguished (Noirfalise, 1987): thermo-Mediterranean (south and south-western coasts and River Guadiana basin, meso-Mediterranean (southern inland, west coast, River Tejo basin, and inland part of the basin of River

Douro), supra-Mediterranean (central and northern inland) and the Ibero-Atlantic oak forests (north- western Portugal).

Summer dryness increases from northwestern Portugal eastwards and southwards. River discharges are closely related to bioclimates: in central and southern inland areas most of the small and medium-sized rivers are dry for three or more months every year.

The present distribution of freshwater fish is related not only to river regimes but also, and perhaps princi- pally, to paleogeographic and recent evolution. An ancient chain of mountains separates the basins of the Rivers Tejo and Guadiana, forming the boundary between the Central and Southern Sectors (Fig. 1). However, recent changes (canals, river captures during winter floods, etc.) have allowed some fish species to spread from one sector to another, apparently mainly from the Southern Sector to the River Tejo. These species are generally rare outside their original area of distribution.

125

ENDEMIC SPECIES

Most of the Portuguese species of native Cyprinidae and one of the two species of Cobitidae are Lusitanian endemics. These are described below.

Chondrostoma lusitanicum and Rutilus macrolepidotus, limited to coastal rivers and terminal segments of main rivers, are exclusively Portuguese. Anaecypris hispanica, Barbus microcephalus, Barbus steindachneri and Chon- drostoma willkommii are restricted, in Portugal, to the basin of the River Guadiana. Barbus comiza inhabits the basins of the Rivers Tejo and Guadiana and is always a rare species. Chondrostoma lemmingii is a Southern Sector species, also found, but not common, in some tributaries of the River Tejo (Collares-Pereira, 1983). Barbus sclateri lives in the River Mira and rivers of the Algarve (Alma~a, 1967), i.e. its area of distribution in Portugal is included in the thermo-Mediterranean zone. Barbus bocagei and Chondrostoma polylepis have a wide distribution in the Central Sector, while Rutilus arcasi is limited to the River Minho and the middle reaches of the Rivers Douro and Tejo (Collares-Pereira, 1983) and Cobitis calderoni only inhabits, in Portugal, the basin of the Douro. Rutilus alburnoides is a Central Sector species which has spread into the River Guadi- ana. Leuciscus pyrenaicus inhabits the Southern Sector and the basins of the Rivers Sado and Tejo.

126 C. Almaga

Fig. 1. Portuguese hydrographic basins. Black circles indicate the position of dams. The broken line separates the Central

and Meridional Sectors.

The affinities of the endemic Lusitanian cyprinids are in part with northwestern African species (Barbus and Anaecypris) and in part with central European species ( Chondrostoma, Rutilus and Leuciscus).

CONSERVATION

The high level of endemicity of the Portuguese native ichthyofauna should justify special concern for the conservation of inland waters. Unfortunately, this is not the case and Portuguese inland waters, particularly those in the industrial part of the country (coastal zone), are not spared from various kinds of pollution. These are frequently responsible for mass mortalities of freshwater fish.

Other deleterious factors affecting inland fish are sand extraction, inadequate fish passes in dams, and the introduction of exotic species (Almaca, 1983, 1988a). In some localities and conditions overfishing is also an important deleterious factor for inland fish, although it seems not to be affecting endemic species particularly. These are indeed not so appreciated as marine and migratory fish, so fishing activities are local and of less importance. Inadequate fish-passes in dams

affect mainly migratory species such as sturgeon (e.g. Acipenser sturio), lampreys (e.g. Petromyzon marinus, and shads (e.g. Alosa alosa). The endemic fauna is protected from this deleterious factor since the seg- ments of large rivers isolated by dams are connected to subsidiary basins (tributaries) where the needs for food, growth and reproduction can be satisfied.

The River Tejo is highly polluted, the main pollutant sources being metallurgy, paper-mills, oil refineries and soap-works. The River Guadiana is probably not greatly polluted now since the pollutant effect of paper-mills and mines seems to have been reduced (Alma~a, 1988b). Urban pollution by domestic sewage is very great in the Tejo and Douro estuaries, but these are not frequented by endemic cyprinids, at least in their lower reaches. Destruction of the spawning areas and turbid- ity caused by sand extraction from river beds are common all over the country and are currently important constraints on endemic species.

The most serious conservation problem for Por- tuguese endemics has, however, been the successive introductions of exotic species dating from the time of the Roman occupation of Iberia. In the present century alone, ten or eleven species have been introduced to inland waters. Among these, Micropterus salmoides now seems to be well-established in reservoirs, and Lepomis gibbosus has become a pest in southern basins, dis- placing native cyprinids (in tributaries of the Rivers Tejo and Guadiana). It is not yet known what role Esox lucius plays in the basins where it has been introduced.

REFERENCES

Alma~a, C. (1967). Estudo das populac, es portuguesas do Gfn. Barbus Cuvier, 1817 (Pisces, Cyprinidae). Revista da Faculdade de Ci~ncias de Lisboa 2a Series, C, 14, 151~,00.

Alma,;a, C. (1978). Rfpartition gfographique des Cyprinidae ibfriques et Secteurs ichthyogfographiques de la Pfninsule Ibfrique. Vestnik Ceskoslovensk~ Spolecnosti Zoologick~, 42, 241-8.

Almaqa, C. (1983). Contemporary changes in Portuguese freshwater fish fauna and conservation of autochtonous Cyprinidae. Roczniki Nauk Rolniczych seria H, 1~, 9-15.

Almaqa, C. (1988a). The conservation of freshwater fishes in Portugal. Communications and conclusions of the Technical Seminar on Parks and Conservation of Nature in Southern European Countries, SNPRCN, Lisbon, pp. 159-62.

Almaqa, C. (1988b). Fish and their environment in large Eu- ropean river ecosystems. Tejo and Guadiana. Sciences de l'Eau, 7, 3-19.

Collares-Pereira, M. J. (1983). Estudo sistem~itico et cito- genftico dos pequenos ciprinideos ibfricos pertencentes aos gfneros Chondrostoma Agassiz, 1835, Rutilus Rafinesque, 1820 et Anaecypris Collares-Pereira, 1983. PhD thesis, Uni- versity of Lisbon.

de Beaufort, L.E. (1951). Zoogeography of the land and inland waters. Sidgwick and Jackson, London.

Noirfalise, A. (1987). Carte de la v~g~tation naturelle des Etats membres des Communautds europ~ennes et du Conseil de l'Europe. Conseil de l'Europe et Commission des Com- munautfs Europfermes, Strasbourg et Luxembourg.

Scharff, R. F. (1899). The history of the European fauna. Walter Scott, London.

APPENDIX

Fish conservation in Portugal 127

1. FRESHWATER A N D MIGRATORY FISH LIVING IN PORTUGUESE INLAND WATERS

Species Status a

PETROMYZONIDAE Lampetra fluviatilis (Linnaeus, 1758) Lampetra planeri (Bloch, 1782) Petromyzon marinus Linnaeus, 1758

ACIPENSERIDAE Acipenser sturio Linnaeus, 1758

ANGUILLIDAE Anguilla anguilla (Linnaeus, 1758)

CLUPEIDAE Alosa alosa (Linnaeus, 1758) Alosa fallax (Lac6p~de, 1803)

SALMONIDAE Oncorhynchus mykiss (Walbaum, 1792) Salmo salar Linnaeus, 1758 Salmo trutta Linnaeus, 1758

ESOCIDAE Escox lucius Linnaeus, 1758

CYPRINIDAE Anaecypris hispanica (Steindachner, 1866) Barbus boeagei Steindachner, 1865 Barbus comiza Steindachner, 1865 Barbus microcephalus Almaqa, 1967 Barbus sclateri Gunther, 1868 Barbus steindachneri Aimaqa, 1967 Carassius auratus (Linnaeus, 1758) Chondrostoma lemmingii (Steindachner, 1866) Chondrostoma lusitanicum (Collares-Pereira, 1980) Chondrostoma polylepis Steindachner, 1865 Chondrostoma willkommii Steindachner, 1866 Cyprinus earpio Linnaeus, 1758 Gobio gobio (Linnaeus, 1758) Leuciseus cephalus eabeda Risso, 1826 Leuseiscus pyrenaicus Gunther, 1868 Rutilus alburnoides (Steindachner, 1866) Rutilus arcasii (Steindachner, 1866) Rutilus macrolepidotus (Steindachner, 1866) Tinca tinca (Linneaus, 1758)

COBITIDAE Cobitis calderoni Bacescu, 1961 Cobitis maroccana (Pellegrin, 1929)

CENTRARCHIDAE Lepomis gibbosus (Linnaeus, 1758) Micropterus salmoides (Lac61~de, 1802)

GASTEROSTEIDAE Gasterosteus aculeatus Linnaeus, 1758

CYPRINODONTIDAE Fundulus heteroclitus (Linnaeus, 1758)

POECILIIDAE Gambusia affinis holbrooki (Girard, 1859)

CICHLIDAE Cichlasomafacetum Jenyns, 1842

BLENNIIDAE Blenniusfluviatilis Asso, 1801

E E E E I?

E

I

I

I

E

aE, endemic to the north Mediterranean; I, introduced.