Fisheries Research, 12 ( 1991 ) 91-100 Elsevier Science Publishers B.V., Amsterdam

91

The effect of man on the fish fauna of the River Guadalquivir, Spain Carlos Granado-Lorencio Departamento de Biologia Vegetal y Ecologia, Facultad de Biologia, Apdo 1095, Universidad de Sevilla, 41080 Sevilla, Spain (Accepted 6 February 1991 )

ABSTRACT Granado-Lorencio, C., 1991. The effect of man on the fish fauna of the River Guadalquivir, Spain. Fish. Res., 12: 91-100. A historical review of migratory and freshwater fish species of the Guadalquivir River basin is presented. This study consists of a general perspective from the 14th Century to the 20th Century, and a description of the present-day ichthyofauna of the Guadalquivir catchment area which is the outcome of different environmental factors (i.e. building reservoirs and channels in the main river, spawning ground damage and poor quality waters, among others) and the result of zoogeographical processes and of an introductions policy in recent times. Prior to the beginningof the 20th Century, there were large populations of migratory species (catadromous and anadromous) in the Guadalquivir River basin, which were the main economic resource of many professional fishermen. The construction of main-stream reservoirs is the major factor in the decline of the most important migratory species during the 20th Century; some of them (sea lamprey, sturgeon and shads) have even disappeared from the Guadalquivir River. However, there are still large eel and mullet populations in the lower reaches.

INTRODUCTION

The Guadalquivir River, situated in the south of the Iberian Peninsula, rises in the Cazorla Mountains at about 1400 m above sea level and flows into the Atlantic Ocean. The river is 680 km in length and has a drainage basin of 63.822 km 2, being the third most important in Spain after the Ebro and the Duero Rivers. From the 18th Century onwards, numerous public works have been put in hand to regulate the flow pattern of the river. Since 1905, 60 reservoirs have been built in the river basin, eleven of them in the main river course. In 1931, the Alcalfi del Rio dam was built about 100 km from the river mouth. Also, since 1795, there have been several channelization exercises designed to avoid the formation of meanders. The most important ones are: Merlina ( 1795 ), 0165-7836/91/$03.50 © 1991 Elsevier Science Publishers B.V. All rights reserved.

92

C. GRANADO-LORENCIO

Los Jer6nimos (1888), Tablada (1926), Ddrsena ( 1951 ), Punta del Verde (1962), Olivillos (1971), Isleta (1972) and La Cartuja (1983) (Fig. 1 ). These works have brought about a considerable reduction in the length of the river (50 km) as well as affecting its hydrological and tidal regimes.

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93

EFFECT OF MAN ON FISH FAUNA OF RIVER GUADALQUIVIR

THE FISH FAUNA

During the last two centuries, the ichthyofauna of the Guadalquivir River has changed. This is due to a range of environmental factors, including among others, the building of reservoirs. To obtain a picture of the fish community of the river in former times, I have reviewed old documents and ancient records which, directly or indirectly, make reference to the ichthyofauna of the river. In Spain, specific ichthyological sources are scarce and the existing documents begin at the end of the 19th Century. Earlier data can be found only in geographical works and in the descriptions of the Iberian Peninsula landscape made by writers and travellers of that time. Data have been classified into two groups: before 1931 and after 1931, for two main reasons. Firstly, prior to 1930, the history of Spanish ichthyology contains only a few works on the fish fauna of the Guadalquivir River. Secondly, the reservoir of Alcal~idel Rio, which is the main obstacle to migration for the migratory species of the river, was built in 1931. MIGRATORY

SPECIES

The migratory fish species (catadromous and anadromous) of the Guadalquivir River basin are: sea lamprey (Petromyzon marinus L.), sturgeon (Acipenser sturio L. ), European eel (Anguilla anguilla L. ), shads (Alosa alosa L. and Alosafallax nilotica Saint-Hilaire) and mullet (Chelon labrosus Risso, Liza aurata Risso, Liza ramada Risso, Liza saliens Risso and Mugil cephalus

cephalus L. ). The first record of migratory species is a fish marketing slip of the Central Market of Sevilla (ca. 1300) (see Table 1). A later reference ( 1526 ) records the existence in the river of all the migratory species with the exception of the TABLE l M i g r a t o r y fish species l i v i n g in G u a d a l q u i v i r R i v e r basin from 1300 to 1990: presence ( + ), absence ( - ), not cited (*), only j u v e n i l e s ( O ) , a b u n d a n t ( + + )

Sea l a m p r e y Yellow eel Sturgeon Mullet Shads

13001

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16242

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18575

18936

19197

1931 s 19859

19871°

1990 II

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D a t a from: IL a d e r o Q u e s a d a ( 1 9 8 0 ) , 2Olmedo G r a n a d o s ( 1985 ). 3Aguilar Pifial ( 1982 ), 4Madoz ( 1 8 5 0 ) , 5Machado Nufiez ( 1857 ), 6Barras de A r a g 6 n ( 1 8 9 3 ) , 7Lozano Rey ( 1 9 1 9 ) , SLozano Rey ( 1931 ), 9Sancho a n d G r a n a d o Lorencio ( 1985 ), ' ° F e r n a n d e z Delgado ( 1987 ), 11 Professional fishers interview.

94

C.GRANADO-LORENCIO

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Fig. 2. Migratoryfish speciesdata distribution in the Guadalquivir River catchment area around 1850. sea lamprey and the mullet, possibly because o f the scant commercial interest of these two species. No other records o f migratory species are available until 1624 and sea lamprey was again not mentioned. Aguilar Pifial (1982) m a d e a reference to a fish assemblage which was very similar to those o f previous centuries. In 1850, four volumes on different social and economic aspects o f several towns and villages o f southern Spain, including data on inland waters and sea

95

EFFECT OF MAN ON FISH FAUNA O F RIVER G U A D A L Q U I V I R

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