INTEGRATED MANAGEMENT OF LAND BASED ACTIVITIES IN THE SAN FRANCISCO RIVER BASIN PROJECT GEF/ANA/OAS/UNEP
Activity 1.3 – Reophylic Ichthyofauna Recuperation in the Lower São Francisco River Basin
Executive Summary of the Final Report
RECONSTITUTION OF THE REOPHYLIC ICHTHYOFAUNA OF THE LOWER SÃO FRANCISCO
Instituto de Desenvolvimento Científico e Tecnológico de Xingó
Canindé do São Francisco - SE
INTEGRATED MANAGEMENT OF LAND BASED ACTIVITIES IN THE SAN FRANCISCO RIVER BASIN PROJECT GEF/ANA/OAS/UNEP
Activity 1.3 – Reophylic Ichthyofauna Recuperation in the Lower São
Francisco River Basin
Executive Summary of the Final Report
RECONSTITUTION OF THE REOPHYLIC ICHTHYOFAUNA OF THE LOWER SÃO FRANCISCO
Coordination Fábio José Castelo Branco Costa Instituto de Desenvolvimento Cientifico e Tecnológico de Xingó
Participants Enaide Marinho de Melo Magalhães LABMAR/UFAL Maria Célia de Andrade Lyra LABMAR/UFAL Manoel Messias dos Santos LABMAR/UFAL Rivaldo Couto dos Santos Júnior Instituto Xingó Sineide Correia Silva Montenegro UFAL
April2003 RECONSTITUTION OF THE REOPHYLIC ICHTHYOFAUNA OF THE LOWER SÃO FRANCISCO
Executive Summary
INTRODUCTION Activity 1.3, “Reophylic Ichthyofauna Recuperation in the Lower São Francisco Basin”, is part of Component I (Environmental Assessment of the Basin) of the Integrated Management of Land Based Activities in the San Francisco River Basin Project, whose main objectives are the identification and assessment of the degree to which inland activities and the regulation of the River affect the hydrology, the water quality (particularly sediment and nutrient transportation), fishing and the aquatic environment in the Basin and in the adjacent coastal zone. Among the objectives there are: 1)Surveying fish species and limnologic characterization of the Xingó Reservoir and of the downstream stretch, up to the Ocean. 2)Identifying and selecting sites for releasing the fish, identifying the necessary procedures for maintaining the economically feasible populations of fish with commercial value. 3)Proposing a sustainable fishing management model, with a monitoring plan. 4)Evaluating historic and current data on limnology, Ichthyofauna and fishing in the Lower São Francisco, proposing measures for reconstitution of the reophylic ichthyofauna. The Activity also treats the etnoscience, studying the different practices and the context in which the resources are used by local populations, contributing to the management and conservation of ecosystems (Diegues, 2001). In this sense, the ethnoecology1 has shown that the fishermen’s knowledge on fish and on the environment is necessary and should be taken into consideration in the fishing planning and management (Thé, 1999; Marques, 1995). This work was carried out by a team of consultants, under the Coordination of the Xingó Scientific and Technologic Development Institute, from June 2001 to December 2002. The Report is divided into eight chapters covering since the area’s characterization, limnology, ethno ecology, fishing production and promotion of the production in the Xingó Reservoir and downstream sector. The endangered species and adverse environmental impacts on the ichthyofauna are emphasized. Additionally, current and past fishing strategies in the Lower São Francisco are presented and reasons for changes are discussed.
1. CHARACTERIZATION OF THE SÃO FRANCISCO BASIN The São Francisco River’s regime is characterized by floods in the summer and no precipitation in the winter. Floods belong to two distinct types: The first one is related
1 Transdisciplinary field studying thoughts, feelings and behaviors intermediating the interactions between human populations and the other elements in the ecosystems, as well as the resulting environmental impacts. i to the great rainfalls at headwaters and the second is due to rains in the Lower Basin. Mean annual river discharge is 2,980 m3/s. The São Francisco Basin presents highly distinct natural sceneries, with great environmental diversity, including cerrado and caatinga biomes. There are regions with great water reserves and areas subject to frequent droughts. Chart 1 presents the Lower Basin’s main characteristics.
Chart 1. Main characteristics of the São Francisco River Basin’s regions.
Region Upper Middle Middle- Lower Lower Characteristics Nascente Pirapora - Remanso Paulo Afonso Pirapora Remanso P. Afonso - FOZ
Altitude (m) 1.600 – 600 1.000 – 400 400 – 300 500 – 0 Mean annual temperature 18 27 27 25 (°C) Mean annual precipitation 1.500 – 1.400 – 800 800 – 400 400 – 1.300 (mm) 1.200
Rainy season Nov. – Apr. Nov. – Apr. Nov. – Apr. Mar. – Sep.
Extension (km) 630 1.090 686 274 Rapid Highlands Practically Plain’s river, waters, cold river, slower River characterization dammed slower, under and flows, subject river sea influence oxygened to floods
1.1. LIMNOLOGIC PARAMETERS Between Três Marias e Pirapora, water temperature in the river varies from 18 to 29°C (average around 24°C), electrical conductivity from 36 a 76 µS/cm (average between 47 and 52 µS/cm), pH from 6.3 to 8.2 and turbidity from 1 to 700 UNT, with the highest values in rainy season, except for the pH, which does not exceed 8.0 (Sato, 1999). In the stretch between the Municipalities of Belém do São Francisco (PE) and Paulo Afonso (BA), includind the Itaparica, Moxotó, PA-I, II, III and-IV Reservoirs, water temperature varied from 26,6 to 28.8°C, electrical conductivity from 58.6 to 74.9 µS/cm and dissolved oxygen from 5.46 to 10.69 mg/l (UFRPE; FADURPE; CHESF,1998). In the analysis in the Xingó Reservoir, water temperature varied from 23.7 to 31º C, electrical conductivity from 59.5 to 84 µS/cm, dissolved oxygen from 6.20 to 10.1 mg/l and total phosphor from 0.0002 to 0.0480 mg/l. In the downstream reach, close to the river’s mouth, water temperature varied from 24 to 30ºC, electrical conductivity from59.4 to 24.7 µS/cm, dissolved oxygen from 6.10 to 13.60 mg/l and total phosphor from 0.0002 to 0.0350 mg/l (UFAL; CHESF, 1999).
1.2. Ichthyofauna In the Middle São Francisco, the migratory fish start to breed in October, right after the driest month. With the arrival of the rains and beginning of the floods, those fish leave ii the marginal lagoons, migrating upstream. After the spawning, the breeding pairs return and the young fish enter the mentioned lagoons. The most important fish in the San Francisco River, regarding biological and fishing aspects, are the bozo, campineiro, croaker, curimatã-pacu, dorado, yellow mandi-açu, yellow mandi, matrinchão, pacamão, pacu, black-fish, piau, piracanjuba, pirambucu, black piranha, red piranha, sofia, sorubim and Tiger fish (Paiva & Campos, 1995). The known Basin’s ichthyofauna is composed of 133 species, including the 73 described for the Três Marias Region (MG), distributed into 65 characiforms, 56 siluriforms, 8 perciforms, two cyprinoids, one symbranchii and one clupeoid (Britski et al, 1984). Recentely, 14 other siluriforms and five characiforms were added (vide Chart 2).
Chart 2. Fish species in the San Francisco Basin
Clupeomorpha Superorder Clupeiformes Order Engraulidae Family Anchoviella vaillanti (Steindachner, 1908)
Ostariophysi Superorder Caraciformes Order Characidae Family Tetragonopterinae Subfamily Astyanax bimaculatus lacustris (Reinhardt, 1874) Astyanax eigenmanniorum (Cope, 1894) Astyanax fasciatus (Cuvier, 1819) Astyanax scabripinnis intermedius (Eigenmann, 1908) Astyanax scabripinnis rivularis (Lutken, 1874) Astyanax taeniatus (Jenyns, 1842) Bryconamericus stramineus (Eigenmann, 1908) Creatochanes affinis (Gunther, 1864) Hasemania nana (Reinhardt, 1874) Hemigrammus brevis (Ellis, 1911) Hemigrammus marginatus (Ellis, 1911) Hemigrammus nanus (Reinhardt, 1874) Hyphessobrycon gr. bentosi (Durbin, 1908) Hyphessobrycon gracilis (Reinhardt, 1874) Hyphessobrycon santae (Eigenmann, 1907) Moenkhausia costae (Steindachner, 1907) Moenkhausia sanctae-filomenae (Steindachner, 1907) Phenacogaster franciscoensis (Eigenmann, 1911) Piabina argentea (Reinhardt, 1866) iii Psellogrammus kennedyi (Eigenmann, 1903) Tetragonopterus chalceus (Agassiz, 1829) Acestrorhynchinae Subfamily Acestrorhynchus britskii (Menezes, 1969) Acestrorhynchus lacustris (Reinhardt, 1874) Oligosarcus jenynsii (Gunther, 1891) Oligosarcus meadi (Menezes, 1969) Cynopotaminae Subfamily Galeocharax gulo (Cope, 1870) Characinae Subfamily Roeboides francisci (Steindachner, 1908) Roeboides xenodon (Reinhardt, 1849) Stethaprioninae Subfamily Brachychalcinus franciscoensis (Eigenmann, 1929) Glandulocaudinae Subfamily Hysteronotus megalostomus (Eigenmann, 1911) Cheirodontinae Subfamily Cheirodon piaba (Lutken, 1874) Compsura heterura (Eigenmann. 1917) Holoshestes heterodon (Eigenmann. 1915) Megalamphodus micropterus (Eigenmann, 1915) Odontostilbe sp. Characidiinae Subfamily Characidium fasciatum (Reinhardt, 1866) Jobertina sp. Triportheinae Subfamily Triportheus guentheri (Garman, 1890) Bryconinae Subfamily Brycon hilarii (Valenciennes, 1849) Brycon lundii (Reinhardt, 1874) Brycon reinhardti (Lutken, 1874) Salmininae Subfamily Salminus brasiliensis (Cuvier, 1817) Salminus hilarii (Valenciennes, 1849) Serrasalminae Subfamily Serrasalmus brandtii (Reinhardt, 1874) Serrasalmus piraya (Cuvier, 1820) Myleinae Subfamily Myleus altipinnis (Va1enciennes, 1849) Myleus micans (Reinhardt, 1874) iv Parodontidae Family Apareiodon hasemani (Eigenmann, 1916) Apareiodon sp. "A" Apareiodon sp. "B" Parodon hilarii (Reinhardt, 1866) Hcmiodontidae Family Hemiodopsis gracilis (Gunther, 1864) Hemiodopsis sp. Anostomidae Family Leporellus cartledgei (Fow1er, 1941) Leporellus vittatus (Valenciennes, 1849) Leporinus elongatus (Va1enciennes, 1849) Leporinus marggravii (Reinhardt, 1875) Leporinus melanopleura (Gunther, 1864) Leporinus piau (Fowler, 1941) Leporinus reinhardti (Lutken, 1874) Leporinus taeniatus (Lutken, 1874) Schizodon knerii (Steindachner, 1875) Curimatidae Family Steindachnerina elegans (Steindachner, 1875) Cyphocharax gilberti (Quoy & Gaimard, 1824) Curimatella lepidura (Eigenmann & Eigenmann. 1889) Prochilodontidae Family Prochilodus affinis (Reinhardt, 1874) Prochilodus marggravii (Walbaum, 1792) Prochilodus vimboides (Kner, 1859) Erythrinidae Family Hoplias aff. lacerdae (Ribeiro, 1908) Hoplias aff. malabaricus (Bloch, 1794) Siluriformes Order Gymnotoidei Su-Order Gymnotidae Family Gymnotus carapo (Linnaeus, 1758) Sternopygidae Family Eigenmannia virescens (Valenciennes, 1847) Eigenmannia sp. "A" Sternopygus macrurus (Bloch & Schneider, 1801) Hypopomidae Family Hypopomus sp. Sternachidae Family v Apteronotus brasiliensis (Reinhardt, 1852) Sternachella schotii; (Steindachner, 1868) Siluroidei Sub-Order Doradidae Family Franciscodoras marmoratus (Reinhardt, 1874) Auchenipteridae Family Glanidium albescens (Reinhardt, 1874) Parauchenipterus galeatus (Linnaeus, 1777) Parauchenipterus leopardinus (Borodin, 1927) Pseudauchenipterus flavescens (Eigenmann & Eigenmann 1888) Pseudauchenipterus nodosus (Bloch, 1794) Pseudotatia parva (Gunther, 1942) Pimelodidae Family Bagropsis reinhardti (Lutken, 1875) Bergiaria westermanni (Reinhardt, 1874) Cetopsorhamdia sp. (aff. C. iheringi) Conorhynchus conirostris (Valenciennes, 1840) Duopalatinus emarginatus (Valnciennes, 1840) Heptapterus sp. Imparfinis microcephalus (Reinhardt, 1875) Imparfinis minutus (Lutken, 1875) Lophiosilurus alexandri (Steindachner, 1876) Microglanis sp. Pimelodella lateristriga (Muller & Troschel, 1849) Pimelodella laurenti; (Fowler, 1941) Pimelodella vittata (Kroyer, 1874) Pimelodella sp. Pimelodus fur (Reinhardt, 1874) Pimelodus maculatus (Lacépede. 1803) Pimelodus sp. (aff. P. blochii) Pseudopimelodus fowleri (Haseman. 1911) Pseudopimelodus zungaro (Humboldt, 1833) Pseudoplatystoma corruscans (Agassiz, 1829) Rhamdella minuta (Lutken, 1875) Rhamdia hilarii (Valenciennes, 1840) Rhamdia quelen (Quoy & Gaimard, 1824) Trichomycteridae Family Stegophilus insidiosus (Reinhardt, 1858) Trichomycterus brasiliensis (Reinhardt, 1873) Trichomycterus reinhardti (Eigenmann, 1917) vi Bunocephalidae Family Bunocephalus sp. "A" Bunocephalus sp. "B" Cetopsidae Family Pseudocetopsis chalmersi (Norman, 1926) Callichthyidae Family Callichthys callichthys (Linnaeus, 1758) Corydoras aeneus (Gill, 1861) Corydoras garbei (R. v. Ihering, 1910) Corydoras multimaculatus (Steindachner, 1907) Corydoras polystictus (Regan, 1912) Loricariidae Family Loricariinae Subfamily Harttia sp. Loricaria nudiventris (Valenciennes, 1840) Rhinelepis aspera (Agassiz, 1829) Rineloricaria lima (Kner, 1854) Rineloricaria steindachneri (Regan, 1904) Rineloricaria sp. Hypoptomatinae Subfamily Microlepidogaster sp. Otocinclus sp. Hypostominae Subfamily Hypostomus alatus (Castelnau, 1885) Hypostomus auroguttatus (Natterer & Heckel, 1853) Hypostomus commersonnii (Valenciennes, 1840) Hypostomus francisci (Lutken, 1873) Hypostomus garmani (Regan, 1904) Hypostomus macrops (Eigenmann & Eigenmann, 1888) Hypostomus cf. margaritifer (Regan, 1908) Hypostomus wuchereri (Gunther, 1864) Hypostomus sp. “A” Hypostomus sp. “B” Hypostomus sp. “C” Pterygoplichthys etentaculatus (Spix, 1829) Pterygoplichthys lituratus (Kner, 1854) Pterygoplichthys multiradiatus (Hancock, 1828
Acanthopterygii Superorder Ciprinodontiformes Order vii Poeciliidae Family Poecilia hollandi (Henn, 1916) Poecilia vivipara (Scheneider, 1801) Perciformes Order Sciaenidae Family Plagioscion auratus (Castelnau, 1855) Plagioscion squamosissimus (Gill, 1861) Pachyurus francisci (Cuvier, 1830) Pachyurus squamipinnis (Agassiz, 1829) Cichlidae Family Cichlasoma facetum (Jenyns, 1842) Cichlasoma sanctifranciscense (Kullander, 1983) Crenicichla lepidota (Heckel, 1840) Geophagus brasiliensis (Quoy & Gaimard, 1824)
Simbranquiformes Order Synbranchidae Family Synbranchus marmoratus (Bloch, 1795)
According to Petrere Jr. (1995), the São Francisco River Basin’s fauna includes 139 species, distributed into 88 genus and 13 families. In the roll of Sanfranciscan fish, Travassos (1960) includes one species of elasmobranch – the Paratrygon ajereba ray (Walbaum) and 138 species of teleostei. Even though the list of endemic species might be incomplete, it points to a great endemism.
2. THE XINGÓ RESERVOIR 2.1. INSERTING THE RESERVOIR IN THE SÃO FRANCISCO BASIN Taking advantage of the River’s natural difference in levels, at the site of the Paulo Afonso Falls, the first Paulo Afonso Hydroelectric Power Plant (PA-I) was constructed, followed by Plants II and III, using the same dam.
viii
Picture 1. Dam of the Xingó Hydroelectric Power Plant. The boost in energy consumption in the Region required the construction of river regulating reservoirs, which were used for new power plants, such as Moxotó, providing a weekly regulation of discharges in the São Francisco River. The Sobradinho Power Plant’s reservoir, with pluriannual regulation, assures a minimum flow of 2,060 m3/s, in critical dry seasons. These sequential dams flood an area equivalent to 5,222. 8 km2 . Figure 1 shows the hydroelectric exploitation in the São Francisco River. The volume of water accumulated in the reservoirs is approximately 68 billion cubic meters. Sobradinho is responsible for around 50% of that total volume, Xingó holds only 6% of it.
Figure 1. Hydroelectric Exploitation in the São Francisco River.
ix The Xingó Reservoir, closed in 1994, was the last reservoir built by CHESF (Companhia Hidroelétrica do São Francisco). It is located between the 584900-640900 and the 8933200-8961200 UTM plane coordinates, between the States of Alagoas and Sergipe, about 2 km upstream from the Municipality of Canindé do São Francisco (SE) and 179 km from the River’s mouth. The Xingó Reservoir is the pilot area for the study on the reconstitution of the ichthyofauna. Almost totally confined in the River’s canyon, with a 60 km extension, at cota 138 m, presenting a 60 km2 surface area and a total volume of 3.8 billion cubic meters.
2.2. ENVIRONMENTAL DIAGNOSIS BRIEF The ichthyofauna diagnosis, prepared prior to the filling of the Xingó Reservoir (ENGE-RIO, 1992), identified only five fish species in the tributaries in its area of indirect influence: • Astyanax bimaculatus (two-spot tetra), • Poecilia vivípara (no popular name), • Oreochromis niloticus (Nile tilapia), • Poecilia reticulata (no popular name), • Hypostomus sp. (carí). For the area under the development’s indirect influence45 fish species belonging to five orders and 17 families were catalogued. The groups with the greatest number of species were the characiforms (46.72%) and siluriforms (33.3%). Other less expressive orders were the perciforms (11.1%), cyprinoids (4.4%) and clupeoid (4.4%).
2.3. ENVIRONMENTAL CHANGES BEFORE AND AFTER THE FILLING The Basic Environmental Plan, prepared by the CHESF, includes several environmental programs for the Xingó Power Plant Reservoir. The physical-chemical analyses of the water(pH, nitrate, ammonia, dissolved oxygen and total phosphor) were carried out before the reservoir was filled and during filling, by the Department of Biological and Biomedical Sciences, of the Federal University of Goiás, and after filling, by the Sanitation Company of Sergipe, in four Stations. The nitrate rate in the post-filling period doubled, compared to that during the construction of the dam, and was three times greater to that before filling. With respect to the pH, there was a noticeable decrease in the post-filling period, compared to the pre-filling (Figure 2).
2.4. PROMOTING THE PRODUCTION IN THE RESERVOIR Traditional fishing in the Reservoir is practically nonexistent, even though verified in some areas as indicated in location map of the fishing areas (Figure 3). It is an incipient activity, concentrated on a few species and with a small volume of catches.
x Figure 2. Limnologic parameters (nitrate and pH) in the Xingó Reservoir.
xi
xii
Figure 3. Fishing areas in the Xingó Reservoir.
xii Given the hydrological changes, the reduction in the native ichthyofauna’s biodiversity and the drop in fishing production in the reservoir, two lines of promotion of the fish production stand out as particularly important. The first consists of adding native fish to the management area (re- populating) and the other involves the intensive raising of fish in floating tanks. With respect to the stocking, a few questions still need to be addressed (the current structure of the fish population in the reservoir, for example). However, the infrastructure supporting fish reproduction, larva culture and native species’ spawning was specially built (Picture 2) and the formation of a breeding stock was started. The promotion of pisciculture in cages and/or in tanks, gained in importance, allowing the adoption of the practice by the communities around the reservoir (Figure 4).
Picture 2. Vista aérea do complexo de reprodução de peixes do Instituto Xingó
Even though it consists of an intensive fish cultivation system requiring skills and knowledge, it was possible to transfer, in a relatively short time, the production technology, through the construction of a aquiculture production demonstrative unit (Picture 3). The beneficiaries were fish farmers, technicians and associations (cooperatives and fish farmers’ associations0
Picture 3. Demonstrative unit of fish production if floating tanks at the Xingó Institute.
xiii ESCALA ESCALA
Figure 4. Floating tanks’ locations map (Xingó Reservoir).
3. LIMNOLOGY IN THE XINGÓ RESERVOIR AND DOWNSTREAM REACH The damming of the great rivers for building the hydroelectric power plants must be considered the first impacts in the environment, causing a series of changes in the limnological characteristics. It resulted, as well, in a reduction of the native ichthyofauna’s biodiversity and, frequently, in a decrease in the fishing production. Systematical information on the limnology of the Lower São Francisco and adjacent coastal zone were obtained four years after the reservoir was formed. The Stations were distributed taking into consideration the reservoir’s form, the confluence of the tributaries and the intake for domestic supply. Of the 19 water collection Stations, for determining the abiotic parameters, phyto/zooplankton and “a” chlorophyll, six are within the reservoir and 13 in the downstream side (see Figure 5). The temperature, electrical conductivity, dissolved oxygen (concentration and saturation), total dissolved solids, salinity and pH were determined in situ, with the use of portable measurement devices. Water transparency was estimated by the reading of the depth at which de Secchi disk
xiv was no longer seen. Nitrate, phosphate, ammonia, silicon and “a” chlorophyll (Strickland and Parsons, 1972) were determined in the Hydro-Chemical Laboratory (LABMAR/UFAL).
Figure 5. Location of the water collection Stations in the Xingó Reservoir and in the downstream side.
Picture 4. Station 1 (downstream from Picture 5. Station 7 (downstream from Paulo Afonso IV Power Plant). the Xingó Power Plant).
xv
Picture 6. Station 14 (Própria-SE). Picture 7. Station 19, at the mouth of the São Francisco.
3.1. PHYSICAL AND CHEMICAL VARIABLES 3.1.1. Water Temperature Water temperature in the Reservoir, in 1998/99, varied from 23.7 to 31.0 ºC, at the surface, to 21 to 30ºC, at the bottom. In the downstream reach, the values verified for both surface and bottom presented the same ranges, 26 to 30 ºC. In the third quarter of 1998, there was a small oscillation in temperature in the Stations. At the surface, it varied from 27 to 29ºC and, at the bottom, from 26 to 28º C. In the same period in 1999, it varied from 23.7 to 26.2°C and from 23.9 to 26.2°C, respectively. In the downstream reach, the values for surface and bottom presented, in 1998 and 1999, a variation from 24 to 28.1º C (Figure 6).
Figure 6. Temperature longitudinal variation’s pattern, between Paulo Afonso and the São Francisco’s mouth.
3.1.2. Electrical conductivity In the samples from the Reservoir, the electrical conductivity varied from 59.5 to 84 µS/cm, at the surface, and from 58.5 to 84µS/cm in the bottom, in the year of 1998. In the downstream
xvi reach, variation at the surface was from 59.4 to 2,310 µS/cm, and from 59 to 5,200 µS/cm, at the bottom. In 1999, the Reservoir presented a surface variation from 61.2 to 72.5 µS/cm and from 59.2 to 70.3 µS/cm at the bottom. In the downstream reach, the electrical conductivity varied from 56.3 to 27,400, at the surface, and from 61.3 to 41,400 at the bottom. At Station 19, given the influence of the maritime environment, the electrical conductivity presents high values. 3.1.3. Dissolved Oxygen (DO) The dissolved oxygen’s (DO) content varied between 6.8 and 9.6 mg/l, at the surface of the Reservoir, and from 4.8 to 8.7 mg/l at the bottom, in 1998. The lowest contents of oxygen were verified at Station 5 (Figure 7). Downstream from Xingó´s Power Plant, oxygen content at the surface varied from 6.6 to 13.6 mg/l, corresponding to 82.2 to 177.1% saturation. and from 6.6 to 13.8 mg/l at the bottom.
Figure 7. Dissolved Oxygen’s longitudinal variation pattern in the stretch from Paulo Afonso to the São Francisco‘s mouth.
3.1.4. Hydrogen Ionic Potential The water’s pH at Xingó and in the downstream reach remained alkaline (7.24 to 8.42), except for the 3rd Quarter (1998 and 1999), at Stations 2, 4, 5, 7 and 11 (pH =6). 3.1.5. Water Transparency Water transparency, measured with the Secchi disk, presents higher values in the Reservoir, with a mean variation from 2.2 to 6.6 m, against a 1.8 to 5.3 m at the downstream reach.. Even though the indices determined from the depth of disappearance of the Secchi disk are not to be used alone, to assess the trophic conditions of the environment, an initial trial was used in this study. Chart 3 shows the trophic classification of the Lower São Francisco, according to those indices. 3.1.6. Nutrients: • Phosphate
xvii The phosphate content in the reservoir varied from 0.6 to 48 µg/l, and from 0.5 to 47 µg/l, in the downstream reach, in 1998. In 1999, the Reservoir presented a variation from 0.2 to 26.7 µg/l and the downstream reach from 0.2 to 21.6 µg/l. The greatest phosphate contents were verified in the 2nd and 3rd Quarters (June and December), in the two years of study. (see Figure 8).
Chart 3. Classification of the Lower São Francisco, according to the depth of the Secchi disk and to the Carlson Index of Trophic Condition (ITC).
Trophic Condition Index Zds Collection site Months ITC(S) ITC (S)* Zds** (m) Classification Classification Mar/98 5.7 34.89 Oligotrophic Oligotrophic Jun/98 5.3 35.94 Oligotrophic Oligotrophic Xingó Reservoir Sep/98 6.2 33.68 Oligotrophic Oligotrophic Dec/98 6.6 32.78 Oligotrophic Oligotrophic Mar/98 4.4 38.62 Oligotrophic Oligotrophic-Mesotrophic Downstream Jun/98 3.7 41.12 Mesotrófico Mesotrófico from Xingó Sep/98 4.9 37.07 Oligotrophic Oligotrophic Dec/98 5.3 35.94 Oligotrophic Oligotrophic ** Zds = Depth of the Secchi disk (m)
50 50
40 40
30 30
20 20
10 10
0 0
Figure 8. Phosphate’s longitudinal variation pattern in the stretch from Paulo Afonso to the São Francisco‘s mouth.
According to the criteria presented by Vollenweider (1968) for the total phosphor, most part of the determined values indicates that both the Reservoir and the downstream reach might be classified as oligomesotrophic-mesoeutrophic (see Chart 4).
xviii
Chart 4. Classification of the Lower São Francisco according to the concentration of total phosphor Total Trophic Condition (P-total) Collection site Months phosphor * VOLLENWEIDER (1968) (µg/l) Classification Mar/98 23.0 Mesoeutrophic Jun/98 20.0 Mesoeutrophic Xingó Reservoir Sep/98 9.0 Oligomesotrophic Dec/98 18.0 Mesoeutrophic Mar/98 23.0 Mesoeutrophic Downstream Jun/98 19.8 Mesoeutrophic from Xingó Sep/98 5.6 Oligomesotrophic Dec/98 5.6 Oligomesotrophic
• Nitrato e Amônia The minimum and maximum nutrient concentration values in the Reservoir, represented by the ammonia (N.NH4) and nitrate (N.NO3), are presented in Chart 5.
Chart 5 – Minimum and Maximum ammonia and nitrate values in the Lower São Francisco (1998/99) RESERVOIR Surface Bottom Parameters minimum maximum minimum maximum 1998 1999 1998 1999 1998 1999 1998 1999 Ammonia (mg/l) 0.0130 0.0500 1.5910 0.2140 0.0180 0.0070 1.6800 0.3360
Nitrate (mg/l) 0.0010 0.0190 0.0980 0.2010 0.0020 0.0230 0.1140 0.2250
According to the classification criteria presented by Vollenweider (1968), for ammonia and nitrate contents, the Xingó Reservoir might be considered as oligotrophic oligotrophic.
xix 3.2. BIOLOGICAL VARIABLES • Chlorophyll Chlorophyll concentration at the reservoir’s surface varied from 0.01 to 13.52 µg/l and from 0.01 to 8.18 µg/l at the bottom. In the downstream reach, it varied from 0.01 to 4.09 µg/l, at the surface, and from 0.01 to 5.66 µg/l at the bottom. Based on the estimated mean values, chlorophyll concentration was higher in the reservoir. The verified values in the 1999 campaign were higher those observed in 1998 (see Figure 9).
Figure 9. Chlorophyll’s longitudinal variation pattern in the stretch from Paulo Afonso to the São Francisco‘s mouth.
4. THE PHYTO AND ZOOPLANKTONIC COMMUNITIES N THE XINGÓ RESERVOIR The study of the phyto and zooplanktonic communities is fundamental to the understanding of the bio-ecologic dynamics of the aquatic ecosystems, especially regarding nutrient replacement and energy flux. In tropical regions, nutrient availability and subaquatic radiation are among the most important abiotic factors. Among the biotic factors are the herbivory and parasitism. Especially in reservoirs, besides the nutrient availability and subaquatic radiation, the phytoplanktonic behavior is associated also to the relation between hydrologic cycles reservoir operation, which affects the discharges and the constant loss of biologic material, given the releases through the turbines and spillways (Brondi, 1994; Calijuri et al., 1999). Several studies have proven that changes in zooplanktonic community’s structure and dynamics will lead to changes in the whole trophic network in the reservoir. The phyto and zooplanktonic communities in the Xingó Reservoir were studied in 1998 and 1999, in the same six Stations where the limnologic supervision was implemented, viewing the observation of the spatial and temporal variations of the main groups of organisms, in quantitative and qualitative terms. The draggings were carried out in the surface layer, with the boat in slow motion, with a speed around 1 knot, for approximately three minutes, with two plankton nets, with 45 µm and 140 µm, for phyto and zooplankton, respectively.
xx 4.1. PHYTOPLANKTONIC COMPOSITION The phytoplanktonic community in the Xingó Reservoir was represented by 91 taxons (16 Cyanophyta, 1 Pyrrophyta, 1 Euglenophyta, 19 Chrysophyta and 54 Chlorophyta). The Chloropyta division was the most representative, with 59% of the identified species, followed by the Chrysophyta with 21% and the Cyanophyta with 18% (Figure 10).
Figure 10. Distribution of the Phytoplanktonic Community (Xingó Reservoir, 1998/99).
According to the wealth of species and to its distribution in the collection stations in the Xingó Reservoir, it was noticed that the number of taxons of the Chlorophyta division was superior to those of the other divisions, in all Stations, and particularly in the Stations 1 through 4, in 1998, and in Stations 1 and 3, in 1999, where it was represented by over 40 species (see Figure 11).
Figure 11. Qualitative distribution of the phytoplanktonic groups in the six collection Stations in the Xingó Reservoir (19998/99).
xxi 4.1.1. Relative Abundance and Spatial and Temporal Variations According to the relative abundance of the identified species, it was verified that there was no dominant species. Most part of the taxons is characterized as rare, meaning a relative abundance inferior to 10%. The most representative species was the chlorophycea Oöcystis sp, with a 48.3% abundance, in Station 6, in 1998. It was the only one classified as abundant (40 - 70,0%). 4.1.2. Occurrence and Density Frequencies • Frequency of Occurrence Regarding the frequency of occurrence, it was noticed that most of the species (43) was considered very frequent, for being present in more than 70% of the analyzed samples. Only eight of the species were considered sporadic, occurring in less than 10% of the samples. The following taxons occurred in all the stations , in both periods of study, being , therefore, classified as very frequent: The cyanophyceae Aphanothece sp, Chroococcus sp, Coelosphaerium sp and Gloeocapsa sp; dinoflagellate Peridinium sp; euglenophyceae Phacus sp; diatomaceae Aulacoseira granulata and Fragilaria crotonensis and chlorophyceaea Botrycoccus sp, Coelastrum sphaericum, Cosmarium sp, Eudorina elegans, Eutetramorus fotii, Sphaerocystis schroeteri, Sphaerozosma sp, Spondylosium sp, Staurodesmus triangularis, Staurodesmu sp, Staurastrum arctiscon, Staurastrum leptocladum, Staurastrum rotula and Stautastrum sp. Density (cel. L-1). The total phytoplanktonic density presented a great flourishing at station 6, in 1998, with a 111,105,441 cel.L-1 value. At the other stations, in the two periods of study, a very uniform distribution in density values was verified. In 1999, however, cell density values were greater (the maximum density was registered at Station 3, with 27,084,257 cel. L-1). In 1998, with the exception of Station 6, the density values were close to each other, with a maximum of 4,156,509 cel.L-1, in Station 5, and a minimum of 3,688,665 cel.L-1, in Station 4 (see Figure 12).
Figure 12. Distribution of phytoplanktonic density (Xingó Reservoir, 1998/99).
xxii The phytoplankton presents a non-uniformity in its spatial and temporal distribution, fact related to the Wind action, precipitation, solar radiation, nutrient availability and, in the case of the dams, with the spillway and turbine releases, in addition to time of residence of the water (Brondi, 1994). Analysis of the monthly samples revealed that densities were greater in 1999. However, in March of 1998, the chlorophyta division presented a high value of 71,322,333 cel. L-1, deserving mention throughout the year. In 1999, the greatest densities were verified in the month of September, when the Chlorophyta presented 28,902,492 cel. L-1 and the Chrysophyta 19,242,144 cel. L-1 (see Figure 13).
Figure 13. Temporal distribution of the density of phytoplanktonic group (Xingó, 98/99).
4.1.3. Specific Diversity and Equitability The biological diversity is representative of the wealth of species in a given community or geographic area. From an ecologic point of view, it is more than just the number of species in a given area, as it depends on the relative abundance of each taxon in the considered environment (Matsumura-Tundisi, 1999 apud Margalef, 1977). The study of the specific diversity indicates the degree of complexity of the community. Therefore, when a community is dominated by one or more species, when individuals of rare species are substituted by other from more common species, or when some species breed more rapidly, the diversity decreases (Omori & Ikeda, 1984). Studies involving the diversity contribute to a better understanding of the trophic conditions in a given ecosystem. The lowest diversity found was 3.52 bits.cel-1, verified at Station 6, in 1998. For Reed (1978), high diversities are verified in stable environments, resulting from the presence of many species, some becoming established, other in their populational peaks and other in declination (see Figure 14).
xxiii
Figure 14. Diversidade específica da comunidade fitoplanctônica no reservatório de Xingó, nos anos de 1998 e 1999.
Based on diversity values, Margalef (1981) characterized as fertile waters those whose diversity of the phytoplanktonic community varied from 1.0 and 2.5 bits, and as clean waters those with values in the 3.0 to 4.5 bits range. In such case, Xingó’s water might be considered as clean (see Chart 6).
Chart 6. Characterization of the Xingó Reservoir, according to the biodiversity values for phytoplanktonic communities. Environments Margalef (1981) Xingó Reservoir (98/99) Fertile lakes 1 – 2.5 bits.cel-1 ------Clean waters 3 – 4.5 bits.cel-1 3.52 – 5.20 bits.cel-1
The equitability values were above 0.50 (0.86 at Station 5, in 1998, and 0.60 at Station 6, in 1999), indicating a equitative distribution of the species, without dominant taxons in the community.
4.2. ZOOPLANKTONIC COMPOSITION 4.2.1. Composition and Relative Abundance The zooplanktonic composition in Ana artificial lake (dam/reservoir) differs from that of natural lakes, with respect to the relative abundance of the main groups of components. In limnetic ecosystems, the truly phytoplanktonic organisms are distributed among three main groups: Rotifer, Cladoceran e Copepod (Matsumura-Tundisi, 1999). The Rotifer group with 27 taxons (29.77%), the Cladoceran with 17 taxons (37.57%) and the Copepod with 7 taxons (26.59%). Additionally, the occurrence of Protozoan (2.73%), Nematodes Ostracod and Insecta was verified, representing 3.35% of the analyzed community (see Figures 15).
xxiv The mean annual relative abundances of the analyzed zooplankton were classified as dominant, abundant, little abundant and rare organisms. The Rotifer Brachionus patulus was the only dominant species, ocurring at Station 5, in 1998., with a 72.59% abundance.
Figure 15. Mean annual relative abundance of the zooplanktonic community in the Xingó Reservoir.
The individuals with the greatest percentages of relative abundance, considering those with values above 10%, are the Rotifer Brachionus patulus and Keratella cochlearis; the Cladoceran Bosminopsis deitersis, Bosmina longirostris and Ceriodaphnia cornuta, and the Copepod Calanoida with the species Notodiaptomus cearensi. Studies carried out in 23 reservoirs in the State of São Paulo (Tundisi et. al/1988 and Matsumura- Tundisi/1999) mention the calanoida as dominant species in oligomesotrophic systems , while the cyclopoida dominate in highly eutrophic systems. It was verified that the Copepod contributed significantly to the numbers in the stations under study, with the Calanoida Notodiaptomus cearensis being the dominant species, suggesting that the Xingó Reservoir is an oligomesotrophic environment. 4.2.2. Specific Diversity and Equitability The biological diversity might be used for expressing only the wealth of species in an area. But, according to Margalef (1983), from an ecological standpoint, it is more than that, depending also of the relative abundance of each species, and how they are distributed in relation to each other. In this study, the diversity was assessed through a mathematical formulation, considering both the number of species in each station and their relative abundance. Shannon Winner index was used as reference. Specific diversity indices, estimated based on the relative abundance of each infrageneric taxon, indicated that the zooplanktonic community, in the six stations studied in 1998 and 1999, is characterized by a high to medium diversity, showing a well diversified zooplanktonic structure. Of the 48 analyzed samples, during the study, 83.33% presented values under 3 bits.ind-1 and above 2 bits.ind-1, with indices varying from 1.26 bits.ind-1 (Station 5, 1998). This was, probably, due to the dominance of the Rotifer Brachionus patulus (72.59%) over the other species, with a
xxv maximum of 3.16 bits.ind-1 (Station 6, 1999). Similar values were verified in other tropical lake systems, in Brazil (Silva /1997, Domingos /1993, Matsumura-Tundisi /1999 and Newmann- Leitão /1994). Regarding the equitability, the taxons in the zooplanktonic community were well distributed, with values oscillating between 0.45 and 0.89, with only one dominant species, the Brachionus patulus. Of the 48 samples, 75% presented values between 0.80 and 0.89, and the remaining between 0.45 and 0.59. In general, they all presented uniform distribution (Figure 16). 4.2.3. Total density and Spatial and Temporal Variation The total zooplanktonic density in the period presented higher values in 1998, with little oscillations. It was registered a minimum value of 1,109 org.m-3 (Station 6, in September, 1999) and a maximum of 2,947 org.m-3 (Station 3, in March 1998). In a general way, considering the seasonality, there was a reduction in the months of March and December, in both years, with peaks in the months of September/98 and June/99.
Figure 16. Zooplanktonic Specific Diversity and Equitability in the Xingó Reservoir, in March, June, September and October, 1998 and 1999.
Regarding the spatial and temporal distribution of the zooplanktonic in the Xingó Reservoir, small variations were detected with respect to the factors affecting the their distribution. In the samples, it was verified a constant presence of the Rotifer Brachionus patulus, Keratella cochlearis and Conochilus dossuarius, the Cladoceran Bosminopsis deitersi, Bosmina longirostris, Bosmina hagmanni, Moina minuta and Cereiodaphnia cornuta, the Copepod Notodiaptomus cearensis, Pseudodiaptomus richardi, Pseudiaptomus gracilis and Thermocyclops minutus , as well as Copepod nauplius. In 83.33 % of the samples, the Rotaria sp., Keratella americana, Cladoceran nauplius, Termocyclops decipiens and Paracyclops sp were present. Other species were less frequent and sporadic.
xxvi 5. THE LOWER SÃO FRANCISCO ICHTHYOFAUNA 5.1. SAN FRANCISCO BASIN DURVEYS In the book “Geeology and Physical Geography of Brazil”, originally published in 1870, Charles Frederick Hartt makes considerations about the Lower São Francisco’s ichthyofauna, with important notes on the biology of the true Piranha (Hartt,1941). According to Paiva & Campos (1995), the ichthyologist John Diederich Haseman travelled through Northeastern Brazil, between November of 1907 and April of 1908, by the Middle and Lower São Francisco, and made the following findings: i) The occurrence of cichlid in the basin; ii) an increase in the number of registered fish; iii) indication that almost all fish species of the Itapecuru River were found in the São Francisco; and iv) the possibility of the Sanfranciscan fish pass over the Paulo Afonso Falls, in their upstream migrations, during the great floods. Other ecological investigations in the San Francisco Basin were carried out by Travassos, permitting the elaboration of a directory of the Sanfranciscan fish (Travassos,1960). Johann Julius Walbaum, in 1972, described the first fish of the San Francisco River Basin, the Prochilodus marggravii, known as curimatá. In the beginning of the XIX Century (1817 to 1830), the Baron of Cuvier described some fish known as dourado (Salminus brasiliensis), red- tail piaba (Astyanax fasciatus), piranha (Serrasalmus piraya) and croaker (Pachyurus francisci).
5.2. SPECIFIC COMPOSITION POSIÇÃO ESPECÍFICA COSTA et all (2000), analyzing the ichthyofauna disembarked in eight Municipalities of the Lower São Francisco (AL/SE), registered the occurrence of 33 freshwater species, seven of which had been introduced and one was a hybrid (tambacu). The marine/estuarine species were represented by 14 species (see Chart 7).
Chart 7. Fish species disembarked in Municipalities of the Lower São Francisco (1998/99) Freshwater Species Marine/Estuarine Species
Scientific name Popular name Scientific name Popular name Steindacherina elegans Aragu Catfish sp. Catfish Leporinus piau Black Piau Selenaspis herzbergii Sea catfish Leporinus sp. Three-spotted Piau Caranx sp. Cavalla Schizodou knerii White Piau Eugerres brasiliensis Mojarra Salminus hilarii White Tubarana Centropomus paralellus Snook
xxvii Centropomus pectinatus Tarpon snook Centropomus pectinatus Tarpon snook Prochilodus sp. Curimatá Tarpon atlanticus Tarpon Prochilodus argenteus Xira Anchoviella lepidentostole Anchovy Prochilodus costatus Curimatá Stellifer sp. Cabeça de côco Pseudoplatystoma coruscans Sorubim Lutjanus sp. Red snapper Serrasalmus rhombeus Black Piranha Mugil brasiliensis Curimã Serrasalmus piraya Red Piranha Mugil sp. Mullet Serrasalmus brandii Green piranha Hyporhamphus sp. Halfbeak Myleus micans Pacu Gerres sp. Mojarra Pimelodus maculatus Spotted Pim Cichla ocellaris Peacock bass Cichla sp. Peacock bass Lophiosilurus alexandri Pacman catfish Pseudopimelodus zungaro Pakamon Hoplias malabaricus Tiger fish Cichlasoma sp. Black Acara Colossoma macropomum Black Pacu
Pachyurus francisci San Francisco’s croaker Pachyurus squamipinnis croaker Hypostomus commersonii Carí Hypostomus margaritifer Painted Carí Sternopygus macrurus weakly electric fish Oreochromis niloticus Tilapia Plagioscion squamosissimus Silver croaker Cyprinus carpio Carp Acestrorhyncus lacustris Lambiá Parauchenipterus galeatus Woodcatfish Astronotus ocellatus Oscar
The following sequence of pictures is part of a Documentary on the Ichthyofauna and Fishing on the Alagoan São Francisco, in the stretch between Xingó and the mouth of the São Francisco, under preparation by Costa (2003).
xxviii
Picture 8. Cari (Hypostomus sp.). The cari or cascarudos belong to the Loricariidae Family, common in South America, with hundreds of species. They are bottom fish, from where they scrap the substratum for food.
A
B
Picture 9. Croaker (A Pachyurus squamipinnis) (B Pachyurus francisci). The majority of the representatives of this family are from the sea, and the most common species are known as croakers, hakes or pescadas.
xxix
Picture 10. Curimatá (Prochilodus sp.). The curimatás belong to the Prochilodontidae Family, feeding from the bottom of rivers and lakes. They are fish of great importance in the fluvial fishing.
Picture 11. Yellow Pim (Pimelodus maculatus). The yellow pims belong to the Pimelodidae Family and occur in many diversified forms.
Picture 12. Pacman catfish (Lophiosilurus alexandri). The pacman catfish belongs to the Pimelodidae Family, being a native of the São Francisco River Basin, also known as pakamon.
xxx
Picture 13. Pacu (Myleus micans). In South America, the Characidae Family comprehends around 30 sub-families, including fish with diversified feeding habits. The pacu represent the Myleinae Sub-Family.
A
B B
Picture 14. White Piau (A Schizodon knerii) and Three-spotted Piau (B Leporinus sp). The piaus belong to the Anostomidae Family, being herbivorous fish.
xxxi
Picture 15. Tilapia (Oreochromis niloticus). Originally from Africa, it was introduced in Brazil in 1971. Belonging to the Cichlidae Family, it is alsoA known as Nile tilapia. B
Picture 16. Peacock bass A (Cichla ocellaris) e B (Cichla sp.). The peacock bass are carnivorous fish, originally from the Amazon basin.
Picture 17. Tiger fish (Hoplias aff. malabaricus). The tiger fish, belonging to the Erythrinidae Family, are a carnivorous species, predators, vastly distributed in South America. They prefer still water environments.
xxxii
Picture 18. Red Piranha (Serrasalmus piraya) and Black Piranha (Serrasalmus sp). BelongingA to the Characidae Family, they are carnivorous predator fish, capable of tearing pieces of their preys with their Sharp jaws.
Picture 19. Black pacu (Colossoma macropomum). Belonging to the Characidae Family, originally from the Amazon Basin, it is an herbivorous fish, eating preferably fruits.
Marques (1995) verified the occurrence of 21 fish species belonging to 12 families in the permanently flooded area of the Marituba Floodplains, in the Lower São Francisco, located in the Municipalities of Feliz Deserto, Piaçabuçú and Penedo (see Chart 8).
Chart 8. Fish species in the Marituba Floodplains Scientific name Popular name Astyanax bimaculatus Two-spot tetra Creatochanes affinis Red-topped tetra Moenkhausia costae Tetra
xxxiii Roeboides xenodon Tetra Acestrorhyncus lacustris Lambiá Serrasalmus brandtii Green Piranha Serrasalmus piraya True (black-tailed) piranha Hoplias aff. Malabaricus (Tiger fish) Erythrinus cf. erythrinus Wolf-fish Leporinus piau Black piau Steindachnerina elegans Aragu Prochilodus argenteus Xira Gymnotus carapo Banded knifefish Sternopygus macrurus Ghost knifefish Parauchenipterus galeatus Woodcatfish Callichthys callichthys Armoured catfish Synbranchus marmoratus Marbled swamp eel Crenicichla lepidota Pike cichlid Cichlasoma sanctifranciscense Cará Centropomus parallelus Fat snook Pseudoplastystoma coruscans Sorubim
Still according to Marques (2001), the fish biodiversity is perceived by the riverine men, who is able to distinguish 9 species of tetra. Continuing with the research begun more than a decade ago, there is the investigation on the “Ecological Characterization of the Marituba Floodplains I – Ichthyology and Limnology of the Marituba do Peixe Environmental Protection Area”. The first samples collection for the Projetc showed that species Eigenmannia trilineata, popularly known in the Region as tubí, whose distribution had only been registered in the Paraná and Paraguay Rivers Basins, occurs also in the São Francisco, That was the first record in the Basin (Sá et all, 2003).
5.3. INTRODUCED SPECIES The dispersion mechanisms, as well as those responsible for introducing new species from the different continents, countries or basins, to the São Francisco Basin, are not sufficiently clear. The silver croaker (Plagiooscion squamossissimus) was introduced in the Sobradinho Reservoir, by DNOCS, trough fish releases.
xxxiv In general, the dispersion mechanisms are associated to the increment in pisciculture in the Basin, which, according to Welcomme (1989), was the case for 41% of the 237 new species. Another way was the stocking of exotic species (aloctone) in the reservoirs, by the electrical sector companies. Even tough the transference of fish species between regions may be an old practice, the associated risks are high and, in the current stage of knowledge, it is difficult to assess the environmental cost of such introductions. In the particular case of the São Francisco, the introduced species were represented by the peacock bass (Cichla ocellaris and Cichla sp.), black pacu (Colossoma macropomum), Nile tilapia (Oreochromis niloticus), Carp (Cyprinus carpio), Oscar (Astronotus ocellatus), silver croaker (Plagioscion squamosissimus) and a hybrid known as tambacu. The statistical analysis of fishing on the Lower São Francisco (1998/99) reveals that the peacock bass is one of the main species, regarding the volume of capture.
5.4. ENDANGERED SPECIES The fishermen of the Alagoan Lower São Francisco point to a decrease in fish and the disappearance of at least 12 species: The yellow pim (Pimelodus maculatus), Aragu (Steindacherina elegans), Woodcatfish (Parauchenipterus galeatus), Lambiá (Acestrorhyncus lacustris), Pacman catfish (Lophiosilurus alexandri), Xira (Prochilodus argenteus), Dourado (Salminus brasiliensis), Sorubim (Pseudoplatystoma coruscans), Pirá (Conorhynchus conirostris), Anchovy (Anchoviella lepidentostole), three-spotted piau (Leporinus sp.) and tetra (Moenkhausia costae). Control of fish disembarkment in the years of 1998 and 99 contributes to the fishermen’s perception. The sorubim and the dourado had little representation. As to the pirá, considered the icon of the Lower São Francisco, there has been no records of its existence for at least 15 years. The impacts on the structure and operation of the fragile and rich ecosystems affected not only the migratory fish, but also the sedentary species, such as the pacman catfish. Other species had their population reduced to a point they could no longer be exploited, as is the case of the three- spotted piau, in the Marituba Floodplains region.
5.5. IMPACTS ON THE ICHTHYOFAUNA Adverse environmental impacts of the dams on the fish communities have been investigated by many authors, specially in those basins which suffered great interventions, as in Iguaçu, Paraná and São Francisco Rivers. In general, the changes resulting from those interventions are very similar. Examples are: • Changes in flow and quality of the water; • Impediment to migratory reproduction;
xxxv • Changes from a lotic to a lentic regime; • Modification of the aquatic communities’ structure.
The sequential dams built along the São Francisco River reduced significantly the downstream floods, preventing the flooding of the marginal lagoons and, consequently, the entrance of larvae and fish eggs in these habitats. According to the environmental prognostic (ENGE-RIO, 1992), the construction of the Xingó Power Plant would imply in changes in the composition, distribution and abundance of the fauna, both upstream and downstream from the dam. The change from a lotic to a lentic aquatic environment, a s well as the resulting changes in water characteristics, will lead to the disappearance, in the area of the reservoir, of fish species that are characteristic to the lotic oxygened environments. This will occur at least to the black carí (Pterygoplichthys etentaculatus) and the painted carí (Hipostomus margaritifer). Among the species which will not be able to migrate upstream are the white piau (Schizodon knerii), the matrinchão (Brycon lundi), the curimatá (Prochilodus affinis), the pacu (Myleus micans) and the pirá (Conorhynchus conirostris). Besides those, there are the typically marine species inhabiting the area, such as the Tarpon snook (Centropomus pectinatus) and the anchovy (Anchoviella lepidentostole), which will no longer reach regions upstream from the dam. The diagnostic and guidelines for continental fishing (MMA, 1998) confirm that the sequence of upstream dams (CHESF’s) would have contributed to significant changes in the composition of the commercial fish in the Lower São Francisco. The construction of dikes along some tributaries, for protecting irrigation projects and riverine communities, against floods, also impeded the entrance of larvae and fish eggs to many marginal lagoons, blocking the access of new individuals in the population (recruiting), thus cutting down the fishing production. Introduction of species from other regions will produce a new impacting wave in the Lower São Francisco, as it happens with the peacock bass (Cichla ocellaris), which has been spreading significantly, year by year.
6. CULTURAL EVOLUTION OF THE FISHERY IN THE LOWER SÃO FRANCISCO (AL): ETHNOECOLOGICAL APPROACH, WITH EMPHASIS ON FISHING STRATEGIES In its course, up to the mouth, the São Francisco River presents variations in physiognomy, reflecting changes in landscape, climate and culture. This study strategically divided the Lower São Francisco Region into three working segments, as presented in Figure 17. The approach to recovering the fishing history in the Lower São Francisco, from a fisherman point of view, was to use interviews, when objective (fishing strategies) and subjective (motivation) information were mined, focusing on both individuals and collective natures.
xxxvi
Figure 17. Areas of distinct ethno ecological approaches.
Contacts were made with fisherman colonies. The oldest fishermen were pointed by the community, for the interviews, and those would recommend other names, known as “true fishermen”. This technique, known in social science as “snow-ball”, was the most used. To acknowledge the history of the raw material used for building the fish-traps, it was adopted the involving ethnoecology method, whose fundament is to identify the connective bases (current and past relations of the fishermen with the environment).
6.1. SOCIAL ORGANIZATION OF THE FISHERMEN In the Lower São Francisco, there are currently six fishermen colonies: Piaçabuçú, Penedo, Traipú, Piranhas, Pão de Açúcar and Delmiro Gouveia. There are also fishermen associations, such as the one in Entremontes (Municipality of Piranhas) and one in Olho d’Água do Casado. It would be expected that fishing activities would be the subject of discussions in those communities, given great number of colonies and associations.
xxxvii Actually, there are many problems and the lack of governmental support for the development and administrative capacitation of the fishermen, viewing a participative management, has been the main reason for the poor performance of the class, in defending their rights. According to those interviewed, the clandestine fishermen would be the most unaware of the fishing regulatory norms, and not interested in observing the legislation, being more into predatory fishing (Figure 18).
Figure 18. Types of predatory fishing mentioned by the fishermen.
This fact has created many conflicting situations, producing two types of clandestine fishermen: (i) the sons of the fishermen (heir to the fishing traditions), with skills to live on fishing, but without a professional registration, and (ii) the “truly clandestine fishermen”, living on fishing with illegal nets, with meshes non-compliant with the legal standards.
6.2. FISHING’S TEMPORAL CLIPPING Fishermen in the Lower São Francisco have noticed that, at least for the past decade, the River is no longer associated to the big floods, which used to rule fishing and their lives, with its water varying from “muddy” (post-flooding) to “clear”. For the elder, the big floods were always associated to abundant food for the fish and to their access to the streams, lagoons and ponds, for procreation, resulting in plentifulness in the following years. It is possible to retrieve, through the fishermen’s memory, the description of physical, biological, social and cultural phenomena, from the “fishing times” (see Chart 9). Some phenomena perceived by those fishermen who lived through those floods are the riponto (arrival of the first waters) and the “general low water” (beginning of river flows). Those phenomena are disappearing with the construction of dams.
xxxviii Chart 9. Identification of physical, biological, social and cultural phenomena from the “fishing times”, according to fishermen. Identification of In times preceding CHESF Time after CHESF and Xingó fishing phenomena and Xingó Physical Time of the Floods: Time of Floods began to scant, the physical “muddy” and “clear” waters, phenomena no longer occur annually. of the low flows; the riponto; As time passes there are more and more time of filling streams, “clear waters” and “muddy waters” lagoons and ponds. become rare.
Biological Time of the “influenza” (fish Many fish species no longer travel upstream migration, for upriver. Those that migrate upstream lay reproduction); the flourishing their eggs but do not hatch; the prawn is of the craibeira is a sign that no longer abundant; the calumbi (plants) the tubarana is coming, disappeared from the margins. The arriving. craibeira is blooms, but few tubaranas come up.
Social Few families; most of the Critical social problems due to the fishermen are relatives; acts decline in fishing; increase in predatory of reciprocity fishing and clandestine fishermen.
Cultural “time of the colonels”; “time “Time of tourism”; “time of the fish of Lampião”; “time of the tanks”; “time of the Xingó Program; railway”. “time of the NGO’s”.
The construction of the Xingó Power Plant has been a critical mark for fishing in the Lower São Francisco. This brought the expressions “before and after Xingó”, in the allusions to the last dam in the San Francisco River. Chart 10 presents a list of popular names of fish and crustraceans of commercial and cultural interest to Areas I and II, indicating the fishermen’s perception regarding their abundance or disappearance from those areas.
6.3. FISHING STRATEGIES Fishing strategy is defined as a combination of equipment, target species and location. It is also the set of decision criteria associating a certain fishing behavior to its respective objectives, benefits and adversities. These adversities and limitations are determined by the economic incentives system, in the form of the fishermen’s earnings, driven by market demands, to search always for bigger fish.
xxxix Chart 10. Fishermen’s perception in Areas II and III (Traipú, Pão de Açúcar and Piranhas), regarding fish abundance or reduction as a consequence of Xingó. fish and crustraceans Still exists Significantly Rare No longer found (popular names) reduced Shrimp X X Prawn X* Sorubim X X Pirá X X Xira or Curimatã X X Tubarana X X Anchovy X X Green piranha X X Cari X X Piau X Pacu X Pacman catfish X Pakamon X
* Mainly in Piranhas and Entremontes.
Historically, fishing in Brazil reflects our cultural roots. An analysis of the type of fish caught in the Lower São Francisco River indicated that many practices were inherited from the Indian, such as preparing the fish, arrows, harpoons, canoe/raft making and building fish traps (fences). From the Portuguese we inherited the fishhooks, fishing weights, casting/dragging nets. From the negroes, we inherited the diversity of baskets. In the Lower São Francisco, arrow fishing, known as batim, is currently extinct. Sea fishing is done close to the River’s mouth, where the fish enter with the tides. The fishermen wait for the right moment to lay their fishing equipment, according to the fish. Four decades ago, there was a type of night fishing, known as “ingarêia”, in the region of Piaçabuçu. The practice consisted of stretching out a white cloth across the canoe, with a nearby light. The fish would jump to the light, hit the cloth and fall into the canoe, being killed with a club. Today, this practice is alive only in the memory of the older fishermen. Similarly to what happened to the marinho and the lambuda, this practice was considered as predatory, by the fishermen. 6.3.1. The Fish The use of fish traps was classified, by fishermen from Penedo, as extinct in the past years. In their account, it was noticed that there were, in the old days, many types of fish traps, made out of
xl several plants (quince tree and bamboo sticks), including a specific trap for catching the woodcatfish (Parauchenipterus galeatus), known as cumbazeiro. Associated to the strategies, there is a whole set of knowledge about fish behavior, fishing areas and type of fishing, as well as on sharing the catches. This accumulated knowledge might be used as subsidy for alternate management projects. With the disappearance of several fish species of the San Francisco River, that is lost too. Anchovy fishing was practiced i the entire Lower São Francisco, but has disappeared almost completely, after the construction of the Xingó Reservoir. There still is some fishing in Traipú, but in really small scale. In Piaçabuçu it still exists, even though all the interviewed fishermen were unanimous to say that fishing production has declined. Fishing with a net across the river is still used, requiring the help of a second man. The casting net is one of the preferred equipment. Some fishermen rather use a bowline plank as a guide, instead of having somebody else helping him in the fishing. To many, this behavior indicates selfishness, implying lack of friendship and cooperation. In the same manner, having a “pigsty”, a kind of corral used by some fishermen in the islands by the river’s mouth, means being the sole owner of the catches. The device known as cuvu, restricted to the reach between Porto Real do Colégio and the estuary, is almost out of use. Some fishing equipment and the fish they are meant for are listed in Da mesma forma, possuir um “chiqueiro”, tipo de corral usado por alguns pescadores das ilhas próximas à foz, significa ser o único dono da produção. Já o apetrecho conhecido como “cuvu”, restrito ao trecho de Porto Real do Colégio até a foz, está quase em desuso. Os apetrechos de pesca e os peixes a que se destinam constam do Chart 11.
Chart 11. Fishing devices and their target fish Devices / practices Fish and crustraceans Hand line Fat snook Hook Wolf-fish, Piau, Fat snook Fishing net tied to boats Mojarra, cambiru, robalo, mullet, piau Fish trap Shrimp, prawn Corral - Cuvú Tiger fish, piranha, piau Bare hands Piau Paternoster line Cavalla Long fishing line - Fishing rod Piau Long handed hoop (puçá) Soft crab Lambuda Extinct
xli Boat pounding (fish All kinds of fish herding technique) Pituca Soft crab Net Bambá, mullet Dragging net Green piranha,mojarra, piau, tarpon snook, pacu, tetra Anchovy net Anchovy Plastic net (dry nylon) Mojarra, cambiru, robalo, mullet Transverse net Piau Tucum net Extinct Casting net Fat snook, cari, bambá
6.3.2. Shrimp and/or Prawn Fresh-water shrimp (Macrobrachium acanthurus) fishing occurs mainly in the Municipalities of Piaçabuçu, Traipú, Pão de Açúcar and Belo Monte. In other stretches, there is more of prawn (Macrobrachium carcinus) fishing is more intense. Fish traps (Picture 20 A) are used for both of them, but, in the old days, long handed hoops (Picture 20 B) were also used. It is still used for the saburica, a small shrimp of the genus Macrobrachium.
Picture 20. Shrimp fishing devices: (A) bamboo fish traps; (B) Long handed hoop.
For shrimp fishing, the strategy is to use a long shafted hoop, with the hoop, tied to a shaft, deposited at the bottom of the river. Some fishermen leave the shaft exposed, to indicate the fishing sites. Other sink them, keeping the site in the memory, as an strategy to prevent theft or removal by other fishermen, which has raised some conflicts in the area. According to the fishermen, shrimp like scents, requiring a different bait than the used for prawn.
xlii Preparing rice powder and potato mass lures is usually a task for the children. Afterwards, the little cakes are baked in a firewood oven. The children, sons of the fishermen, participate, along with their mothers, in the cleaning of the shrimp, taking off the heads and removing the mud. After these procedures, the shrimp is boiled in water with salt and sold, by the liter, in markets, for around US$0,30 a liter.
6.4. CONNECTIVE BASES To understand how the fishermen relate to the environment, it is necessary to understand the relations in the past and follow the environmental changes. According to Marques (1995), 10 years ago the fishermen in the Marituba do Peixe Floodplains used more vegetal by- products in the fishing. The connections between fishermen and botanical components were diversified, not restricted to fishing devices, but also related to recreation, cure, handcrafts and food. Currently, the use of plants in the handcraft fishing is being replaced by nylon meshes and PVC pipes. The oldest fishermen say that the bamboo stick fish traps (poaceae) were the most used in the entire Lower São Francisco, given the availability of the raw material. By the end of 2002, the River’s situation, without floods, kept the waters “clear”, what, in their perception, resulted in losses, with great damages to the fish traps, caused by three-spotted piaus (Leporinus sp.), land turtles (Phrynops sp.) and otters (Lontra longicaudis). The problem is being investigated, to assess the “innovations” brought by the environmental changes. It is exactly the combination of the type of strategy with the type of environment (clear or muddy waters), used both for shrimp and for fish, that drives the fisherman to maximize the prawn catches. In that manner, it wws verified a replacement of the bamboo fish traps by those with screens (Areas I and II) or made with PVC (Area III). In Piranhas and Entremontes, the manufacturing of PVC fish traps is well established, reflecting an individual action initiated almost 10 years Aug.
6.5. FISHING IN 2002 The handcraft fishing, source of food and support to many fishermen populations, is far from becoming a sustainable practice. It is under many and multiple economic, ecological and cultural pressures, which affects its continuation. The fishing activity in the Lower São Francisco is declining, due to the insufficient rainfalls, to the damming of marginal lagoons, to the pollution from agricultural activities and to the operation of the reservoirs. This situation, aggravated by the adverse conditions of life of the fishermen, has lead to an inadequate exploitation of the fish, compromising the already vulnerable stocks. In the perception of the fishermen, the lack of floods and floodplains is the main cause of the disappearance and appearance of species in the River. They explain, in simple language, the changes verified with the construction of dams. Many of these phenomena should be further studied, to a better understanding of the fishing.
xliii The time of “clear waters” is associated to a lower flow, leaving many uncovered areas, thus reducing the fish and shrimp habitats. The dams impose a negative impact in the aquatic fauna, particularly on the ichthyofauna, reducing the fishing commercially valuable stocks of migratory autochthon species. For this reason, the preservation of the resources demands more intense management programs. In order to overcome the problem, the responsible agencies recommend the incorporation of aquiculture to the existing activities of the handicraft fishermen, turning them into fishermen- aquiculturists. However. Aquiculture is not part of their traditional culture, requiring skills and knowledge beyond those in which fishing is contained. Besides, the current status of social disorganization of the colonies would not contribute to an activity requiring a well structured associativism. But, what to do in face of the “time of ecotourism” and of the “time of fish-tanks”? The environmental issue requires an integration of different knowledge and concepts, because interaction between society and nature are not dissociable from the relation that men have with each other. Ecological facts are also non-dissociable from social facts. The urgency for a participative planning to meet the needs of the several social segments, especially of those most marginalized in the natural resources degradation processes, requires the valorization of cultural and natural heritage, in addition to a re-orientation of the development model.
7. FIHING PRODICTION IN THE LOWER SÃO FRANCISCO Fishing resources management assumes an ample understanding of all components of the system, including fish, organisms, the environment and the involved people. Information on the disembarked fish and on fishing activities in the Lower São Francisco are scarce, dispersed and lack consistency, as in other regions of the basin. Available statistics do not cover long series, making it difficult to diagnose fishing in the region. Estimates for the São Francisco indicate a total annual catch of 2,500 tons. Other statistics and inferences on fishing production are found in woks covering 29 riverine communities, estimating the production in 2,534.4 and 1,790.7 tons, for 1951 and 1954, respectively (Menezes, 1956). Travassos (1958) and Braga (1964) estimate a production of 3,500 tons, for 1958. Integrating information for all areas of the São Francisco Basin, it is concluded that, in 1996, fishing production was approximately 15,000 ton/year, with 9,000 tons coming from the power plant reservoirs. The Lower São Francisco contributes with around 8.34% of the total catches in the River and tributaries. Fish disembarkment control provides information on the production, fishing efforts and number of fishermen, among other, being fundamental for the assessment of River reclamation. Fishing might be considered an important indicator of the Basin’s environmental quality, as the availability of fishing resources, qualitative and quantitatively, reflect the conditions for occupancy and use in the Basin.
xliv Chart 12 Fishing production in Penedo (AL), in a 6-year period. Year Production (kg) 1949 119,045 1950 142,857 1951 60,006 1952 59,837 1953 93,491 1954 40,748
Other information on the fishing production in the Lower São Francisco are found in publications on the Fishing Statistics of the State of Alagoas, produced by the Agreement between the Superintendence of the Northeastern Development (SUDENE) and the Federal University of Alagoas (UFAL), in the Municipalities of Penedo, Piaçabuçú and Traipú, for 1973, 1974 and 1975 (Chart 13).
Chart 13. Fishing production (kg) in Penedo, Piaçabuçú and Traipú (1973/74/75). Production (kg) year Traipú Penedo Piaçabuçú 1973 ------149,375 137,309 1974 96,317 167,671 246,919 1975 70,540 85,408 218,945
At the end of the 90’s, the UFAL and the Fishing Enterprise of Alagoas, in partnership with CHESF, carried out a survey of the fishing activities in the stretch between the Xingó Reservoir and the mouth of the São Francisco. The disembarkment control covered seven Municipalities plus a location in the States of Alagoas and Sergipe: Piranhas (AL), Entremontes (AL), Traipú (AL), São Brás (AL), Penedo (AL), Piaçabuçu (AL), Propriá (SE) and Neópolis (SE). The information collected included production, per species, type of boat, number of fishermen, number and kind of fishing equipment, fishing sites, fishing durations and price of sale of the fish, by the fisherman. The results of fishing monitoring in 1999 are shown in the charts and figures ahead. A comparative analysis is made, considering the year of 1998 and previous years, particularly for the Municipality of Traipú (only location in which it was possible to establish the comparisons).
Chart 14. Total production and contribution (%) per Municipality/location (1999)
xlv Municipality/location Production (kg) contribution (%) Piranhas 18,720.4 10.76 Entremontes 14,713.3 8.46 Traipú 14,937,4 8.59 São Brás 6,828.3 3.92 Própria 20,395.2 11.73 Penedo 20,801.1 12.00 Neópolis 16,008.4 9.21 Piaçabuçu 61,416.0 35.33 TOTAL 173,820.1 100
Chart 15. Monthly production (kg) per Municipality/location -1999.
Entre - Meses Piranhas Traipú S. Brás Propriá Penedo Neópolis Piaçabuçu TOTAL Montes Jan. 1,140.2 1,392.4 803.6 873.2 2,462.8 2,299.3 2,088.4 5,907.0 16,966.9 Feb. 1,132.1 1,207.0 703.7 324.2 1,271.5 1,848.4 1,292.6 5,122.0 12,901.5 Mar. 2,330.5 1,669.4 1,227.2 464.5 1,346.8 1,768.7 822.8 4,433.0 14,062.9 Apr. 2,266.1 248.9 1,245.1 390.7 1,180.6 1,812.4 899.5 4,594.0 12,637.3 May 1,474.0 1,251.2 1,437.4 421.0 1,301.8 2,086.7 1,635.1 4,575.0 14,182,2 Jun. 1,268,0 1,214.0 1,478.4 391.8 1,165.1 1,567.7 1,450.1 6,080.0 14,615.1 Jul. 1,478.4 1,169.2 1,625.4 411.5 1,313.9 2,151.3 1,898.6 8,104.0 18,152.3 Aug. 1,173.3 1,044.7 1,462.0 497.5 1,306.6 1,135.1 1,347.7 8,488.0 16,454.9 Sep. 1,195.4 1,292.2 1,207.8 335.2 1,648.6 1,648.2 1,355.5 6,872.0 15,554.9 Oct. 1,260.0 1,140.2 1,449.1 678.0 2,149.5 1,701.9 1,309.9 7,241.0 16,929.6 Nov. 1,952.4 1,827.2 1,293.7 942.0 2,207.0 1,613.0 963.2 ----- 10,798.5 Dec. 2,050.0 1,256.9 1,004.0 1,098.7 3,041.0 1,168.4 945.0 ----- 10,564.0 TOTAL 18,720.4 14,713.3 14,937.4 6,828.3 20,395.2 20,801.1 16,008.4 61,416.0 173,820.1
Total 1999 production (Chart 14) shows a reduction in the order of 12.8%, with reference to 1998 (Chart 16 and Figure 21). The Municipalities of São Brás, Propriá, Penedo and Piaçabuçu presented a reduction in the volume of catches (Piaçabuçu with the most expressive falloff).
Chart 16. Total production and contribution (%) per Municipality/location (1998)
xlvi Municipality/location Production (kg) contribution (%) Piranhas 14,188.8 7.12 Entremontes 10,191.1 5.11 Traipú 11,560.4 5.80 São Brás 7,103.8 3.56 Própria 21,103.9 10.58 Penedo 24,583.5 12.33 Neópolis 14,514.8 7.27 Piaçabuçú 96,185.5 48.23 TOTAL 199,431.8 100.00
Figure 21. Production per Municipality/Location (1998 – 99). All locations, except for Penedo and Piaçabuçú, increased their share in the total fishing production, in comparison with 1998 (Figure 22).
Figure 22. Contribution to the total (%), per Municipality/Location (1998 -99).
xlvii Chart 17. Monthly production(kg), per Municipality/Location (1998)
Entre- Meses Piranhas Traipú S. Brás Propriá Penedo Neópolis Piaçabuçu TOTAL montes
Jan. 1,277.2 836.4 965.1 779.9 2,039.5 2,710.1 1,894.1 10,735.0 21,237.3
Feb. 1,127.9 796.0 766.7 503.1 1,353.3 1,457.8 1,405.0 8,637.0 16,046.8
Mar. 1,405.6 1,598.8 1,024.4 752.9 1,430.0 2,080.1 1,478.5 12,829.0 22,599.3
Apr. 1,026.1 633.5 672.5 571.8 1,447.3 1,790.2 854.2 9,542.5 16,538.1
May 1,418.8 764.1 1,323.1 756.4 1,410.0 2,356.7 1,104.1 10,006.0 19,139.2
Jun. 1,310.5 602.0 1,130.7 746.8 1,472.0 1,713.0 862.5 10,281.0 18,118.5
Jul. 1,213.7 895.6 1,488.4 723.7 1,400.1 1,980.6 1,113.8 8,410.0 17,225.9
Aug. 1,181.3 1,012.7 1,236.8 418.4 2,633.0 2,368.0 992.5 7,236.0 17,078.7
Sep. 974.8 1,012.8 922.6 512.9 1,855.6 1,721.4 820.3 7,056.0 14,876.4
Oct. 993.2 990.7 907.6 503.0 2,740.1 1,957.2 1,055.8 2,819.0 11,966.6
Nov. 1,180.5 531.7 520.1 482.5 2,082.7 1,614.6 1,249.9 4,726.0 12,388.0
Dec. 1,079.2 516.8 602.4 352.4 1,240.3 2,833.8 1,684.1 3,908.0 12,217.0
TOTAL 14,188.8 10,191.1 11,560.4 7,103.8 21,103.9 24,583.5 14,514.8 96,185.5 199,431.8
Traipú is the only disembarkment location with records from previous years, as shown in Chart 18 (Source: Fishing Statistics of the State of Alagoas, labmar/ufal, Issues number 02 and 03, 1974-75 data).
Chart 18. Production in Traipú (1974, 75, 98 and 99). Year Production (kg) 1974 96,317.0 1975 70,540.0 1998 11,560.4 1999 14,937.4
Ichthyofauna in the Lower São Francisco is represented by marine and estuarine species, with expressive participation in the disembarkments at Piaçabuçu and Penedo, especially the Carangidae Family (anchovy = palombeta) and typical freshwater species. The latter include exotic species of the Cichlidae (peacock bass and tilapia), Cyprinidae (carp) and Characidae (black pacu) Families. The presence of a hybrid was verified: the tambacu, resulting from the cross-breeding of the pacu and the black pacu.
xlviii Identification of the individual species shows that the marine and estuarine ichthyofauna disembarked in the eight sampling sites is represented by seven and six main families, respectively. The relative participation of these families is displayed in Figures 23 and 24.
Figure 23. Relative participation of the main families in the freshwater ichthyofauna of the Lower São Francisco (1998 / 1999).
Figure 24. Relative participation of the main families in the marine and estuarine ichthyofauna of the Lower São Francisco (1998 / 1999).
The relative participation of the introduced species, in the disembarkment, was 18.7%, in 1998, and 22.4 e%, in 1999. The peacock bass (Cichla sp.) was the most frequent species, reaching a 6.2 tons production, in 1998, and 10.5 tons in 1999. The second most frequent was the tilapia (Oreochromis sp.), with productions of 2.1 and 1,7 tons, in 1998 and 199, respectively. The reophylic species with a high commercial value, such as the sorubim (Pseudoplatystoma coruscans) and the dourado (Salminus brasiliensis), had inexpressive participation in the disembarkment, with a maximum of one ton, in 1999. General aspects of the fishing in the Lower São Francisco, regarding fishing devices, boat kinds and fish trade, are illustrate by the sequence of pictures which constitute the Documentary on the Ichthyofauna and Fishing on the Alagoan São Francisco (Costa,2003).
xlix
Picture 21. Making fish traps. Picture 22. Wood (A) e PVC (B) fish traps.
Picture 23. Fisherman’s house, by the Picture 24. Sea fishing boat. River’s mouth.
Picture 25. Fishing canoes (Piaçabuçú). Picture 26. Fishing sail-boat.
l
Picture 27. Rowing Pesca em canoa a remo. Picture 28. Taking off the macrophytes from the net, after fishing.
Picture 29. Fishing canoe (Traipú). Picture 30. Boats in Piaçabuçú.
Picture 36. Free market in Piranhas. Picture 38. Fish market in Penedo.
li 8. RE-POPULATING THE XINGÓ RESERVOIR In the case of the Xingó Reservoir, studies on the structure of fish populations, under the new situation, are scarce. It is imperative to carry them out, at once, to provide the necessary information to assess the stocks. The lack of information regarding other issues, such as zoning of eggs and fish larvae concentration areas, turned impossible any attempts to re-populate the Reservoir. However, this management alternative (re-populating) must be pursued, in the Xingó case, as there are no long free stretches upstream. In this direction, Activity 1.3 began the first surveys, aiming at characterizing the composition, the ichthyofauna’s diversity and the fishing production in the ecosystem. It proceeded with the identification and selection of areas passible of stocking, carrying out ywo limnologic campaigns in the pre-selected areas.
8.1. RE-POPULATING AREAS 8.1.1. IdentificaTION AND Selection of Re-Populating Sites The decision about the stocking areas is one of the premises for the success of a re-populating program. With that in mind, the Activity’s technical team ran all the extension of the Reservoir, in an attempt to identify, characterize and select the re-populating sites. The nine identified areas are shown in Figure 25. All of them are close to the confluence of streams, as there are no permanent tributaries in the stretches upstream of the Xingó Power Plant. 8.1.2. Physical, Chemical and Biological Parameters of the Re-Populating Areas Previously, a limnologic campaign was carried out in the Reservoir, in order to verify the spatial variation (channel and reentrances) and the diverse physical, chemical and biologicaç parmeters. He sample collection stations are listed in Chart 36.
Chart 36. Preliminary Collection Stations (Mar.2002)
Stations UTM Coordinates (24L)
1. Pau de Arara Stream 0632230 E / 8937469 N 2. Near the dam 0631640 E / 8937087 N 3. Reentrance upstream from the Pau de Arara Stream 0631343 E / 8937805 N 4. Reentrance downstream from Luiz Xavier’s farm 0631277 E / 8938563 N 5. Fish-tank modules (Luiz Xavier’s farm) 0629923 E / 8939772 N 6. Talhado Stream 0621453 E / 8950159 N
lii
lv
Figure 25. Re-populating areas in the Xingó Reservoir.
Water samples were colected in a Van Dorn type of bottle, with 2.2 liter capacity, at two depths (surface and bottom), in five of the six Stations (Chart 37), after measurementof the maximum depth. The vertical profiles were determined for the six Stations, with direct measurement of temperature and dissolved oxygen, with the help of a portable measuring device (Oxymeter WTW – OXI 197).
Chart 37. Physical, Chemical and Biological Parameters in the Xingó Reservoir (Mar.2002)
Secchi O2 saturation Nitrate Turbidity Stations - (m) (%) N.NO3 (mg/l) (NTU) S 68.2 0.054 12.0 Pau de Arara Stream 1.0 B 51.0 0.075 12.0 S 69.0 0.044 13.0 Near the dam 1.5 B 35.8 0.047 2.0 Reentrance upstream S 79.7 0.029 6.7 from the Pau de Arara 1.5 B 64.3 0.052 8.2 Stream. S 74.9 0.081 9.5 Reentrance downstream 1.0 from Luiz Xavier’s farm. B S 66.8 0.045 8.5 Fish-tank modules (Luiz 1.0 Xavier’s farm). B 54.6 0.041 6.5 Total Ammonia Dissolved Chlorophyll phosphor (mg/l) phosphor (mg/l) (µg/l) (mg/l) S 0.04 0.128 0.049 3.47 Pau de Arara Stream B 0.06 0.155 0.098 S 0.04 0.108 0.065 3.21 Near the dam B 0.02 0.074 0.049 Reentrance upstream S 0.02 0.094 0.065 4.28 from the Pau de Arara B 0.05 0.128 0.082 Stream. Reentrance downstream S 0.02 0.141 0.114 4.54 from Luiz Xavier’s farm. B S 0.03 0.121 0.065 3.68 Fish-tank modules (Luiz Xavier’s farm). B 0.02 0.128 0.049
Note: S-Surface/B-bottom
liv The water temperature profiles show stratification in some stations, with emphasis on Station 5 (see Figure 26).
Figure 26. Water temperature profiles in the Xingó Reservoir (Mar. 2002)
The dissolved oxygen profiles did not present strong variations in the stations, except for Station 6 (Talhado Stream), which presented a significant stratification, with dissolved oxygen levels reaching zero mg/l, after a 10 m depth (Figure 27).
Figure 27 Dissolved oxygen profiles in the Xingó Reservoir (Mar. 2002)
Based on historic and current data, nine areas with favorable characteristics for stocking native species were identified and selected (vide Chart 38).
lv Chart 38. Re-Populating Areas (Aug./2002)
Selected sites in the Reservoir UTM Coordinates (24L)
1 . Pau de Arara Stream 0632206 E / 8937468 N 2 . Curituba Stream 0623921 E / 8938623 N 3 . Uruçu Stream 0627219 E / 8942673 N 4 . Poço da Cachoeira Stream 0623984 E / 8941132 N 5 . Águas Mortas Stream 0623540 E / 8947216 N 6. Olho d’Água Stream 0619177 E / 8946389 N 7. Grande Xingó Stream 0609391 E / 8947482 N 8. Mandu Stream 0606655 E / 8950790 N 9. Baixa da Velha Stream 0606097 E / 8951223 N
Some physico-chemical parameters were measured in situ at the selected re-populating sites, at the surface, with the help of portable measuring devices (Chart 39).
Chart 39. Physico-Chemical Parameters of Water in theSelected areas (Aug./2002)
Electrical Dissolved Oxygen Max. Temperature Station pH Condutivity oxygen Saturation depth (m) (°C) (µS/cm) (mg/l) (%)
1 - Pau de Arara Stream 34.0 8.15 24.7 75.5 7.56 97.0
2 - Curituba Stream 8.5 8.67 26.7 79.9 7.87 97.3
3 - Uruçu Stream 7.0 8.37 25.6 78.3 7.63 98.4
4 - Poço da Cachoeira 25.5 8.42 25.3 71.4 7.81 91.2 Stream
5 - Águas Mortas Stream 54.0 8.92 25.3 84.8 8.62 81.4
6 - Olho d’Água Stream 9.5 9.59 26.4 80.5 8.40 105.6
7 - Grande Xingó Stream 6.5 8.41 25.7 111.1 6.88 150.2
8 - Stream do Mandu 13.0 8.15 26.9 127.5 8.09 100.0
9 - Stream Baixa da Velha 11.0 7.80 27.3 129.0 7.88 94.3
lvi 8.2. PRODUCTION AND STOCKING OF THE YOUNG FISH Until the early 80’s, only two native species of the São Francisco Basin were artificially hatched: produced: The curimatã-pacu (Prochilodus marggravi) and the “true” piau (Leporinus elongatus). With the research done at CODEVASF’s Piscuculture Station, it was also possible to produce, regularly, young fish of 14 other species, with emphasis to the sorubim (Pseudoplatystoma coruscans), the dourado (Salminus brasiliensis), the pirá (Conorhyncus conirostris), the yellow mandí (Pimelodus maculatus) and the matrinchã (Brycon lundii). In 1977, CODEVASF implemented the “Live Fish Project”, near the Marituba do Peixe Village (Municipality of Penedo), in the Lower São Francisco, in partnership with the fishermen community. This Project consists of raising young fish of native species, such as the true piau (Leporinus elongatus) and the curimatã-pacu (Prochilodus marggravi), in cages installed into the Marituba River, until they reach 12 to 15 cm, when they are to be released into the natural environment. The Pisciculture Station of the São Francisco Hydroelectric Power Company, located in the Municipality of Paulo Afonso (BA), maintains pure bred breeding stocks of the following native species: curimatã-pacu (Prochilodus argentus), dourado (Salminus brasiliensis), pacman catfish (Lophiosilurus alexandri), oremon catfish (Pseudopimelodus fowleri), two-spot tetra (Astyanax bimaculatus), true piau verdadeiro (Leporinus elongatus), sorubim(Pseudoplatystoma coruscans) and cari (Pterygoplichthys etentaculatus). In its almost 30 years of operation, the Pisciculture Station has been producing young fish of native species, specially curimatãs, piaus and pacman catfish, in order to re-populate CHESF’s lakes and reservoirs. The available information on the production of post-larvae and young fish of native species indicate that the current production is adequate to meet the re-populating demands. Even though some re-populating has been done in the Lower São Francisco, no posterior monitoring was carried out, which impedes the evaluation of those actions.
9. CONCLUSÕES Characterization of the San Francisco Basin • The Lower São Francisco’s ichthyofauna is little studied, what is proven by the small number of works on the regional fish. This fact exposes taxonomic abd ecologic doubts. • Some important fish species disappeared almos completely, as it happened to the pirá (Conorhynchus conirostris), without any signs for the past 20 years. • The big migratory fish, such as the sorubim(Pseudoplatystoma coruscans) and the dourado (Salminus brasiliensis), had their population extremely reduced. The insertion of the Xingó Power Plant Reservoir in the San Francisco Basin • No diagnosis of the ichthyofauna has been made, after the formation of the Xingó Reservoir.
lvii • Studies about the structure of fish populations are scarce, turning imperative their immediate implementation, to provide subsidies for sizing the stocks, and for efficient procedures viewing the management and protection of fishing resources. • Fish breeding in cages is an activity which has been consolidating in the Region, particularly in the Xingó Reservoir. Limnology of the Xingó Reservoir and downstream reaches • The oligotrophical characteristics and the high transparency of the water column favor the development of submersed macrophytes in the floodplains. Phyto/Zooplanktonic Communities in the Xingó Reservoir • The Xingó Power Plant Reservoir might be considered one with “clear” waters, given the diversity values of the phytoplanktonic communities. • The dominance of the Notodiaptomus cearensis species suggests an oligomesotrophic environment for the Reservoir. The Lower São Francisco’s Ichthyofauna • The Lower São Francisco’s ichthyofauna is not well studied, if compared to other Basins. • There is a significative occurrence of introduced species, from other basins and regions. • The impacts of anthropic actions on the structure and behavior of the fragile and rich ecosystems of the Lower São Francisco affect not only the big migratory fish, but the sedentary species as well. Fishing Cultural Evolution in the Lower São Francisco, in Alagoas: Ethnoecological Approach with Emphasis on Fishing Strategies • The ecologic knowledge of the fishermen, being an important source of information for fishing management, should be used as an strategy for occupying new spaces in the exchange of experiences and learning, among the diverse users, knowledge developers and public administrators. • The environmental changes caused by the construction of the Power Plant were determinant in the changes in the raw materials used for making fish traps in the Lower São Francisco. Fish Production in the Lower São Francisco Based on the analysis of the fishing activities along the São Francisco, it is possible to highlight the following: • The drop in fishing production disembarked in the eight control points, in the period of study (1998/99);
lviii • The freshwater species presenting the greatest volume of catch is the curimatã (Prochilodus sp.), probably due to the stocking practice implemented in the Region by the ichthyofauna re-populating programs; • The significative presence of introduced species, particularly the peacock bass (Cichla ocellaris) and the tila Oreochromis niloticus); • The little participation, in the disembarkments, of migratory species such as the sorubim and the dourado, whose spawning coincide with the rainy season; • Besides the rational monitoring of the fishing, which should not be limited to the temporary suspension of fishing, it is necessary to extend the control to other anthropic actions (changes in river stages due to upstream reservoirs operation, degradation of spawning sites and natural hatcheries, contamination, etc.); • Lack of monitoring during the gonadal cycle of the species, in view of the changes imposed to the River, which demands an evaluation of the legislation adopted for the Lower São Francisco. Re-populating the Xingó Power Plant Reservoir • Implementation of the ichthyofauna recomposition program requires additional information on the zoning of eggs and fish larvae and an ichthyofauna survey of the A implementação do programa de recomposição da ichthyofauna exige informações adicionais sobre o zoneamento de ovos e larvas de peixes e do levantamento da fauna ictiológica do reservatório da UHE de Xingó.
10. RECOMMENDATIONS 10.1. IMPLEMENTATION OF A PERMANENT RE-POPOPULATING AND FISH DISEMBARKMENT CONTROL PROGRAM IN THE LOWER SÃO FRANCISCO Analysis of the historic data obtained by the Activity indicate that fishing activities in the Lower São Francisco are in evident decline, due to several problems, amog which are the following: • Barriers to the reproduction and feeding migrations of the fish; • Reduction in fish spawnig habitats; • River flow regulation, due to reservoir operation; • Increase in predatory fishing; • Sediment deposition in river channels; • Lack of governmental support for administrative capacitation of the fishermen, viewing a participative management. The whole situation, aggravated buy the fishermen’s low conditions of life, has been the cause for inadequate fish exploitation, compromising the already vulnerable stocks. Record of production and fishing activities do not include historical series of data, making control even more difficult.
lix With the environmental changes and the impacts on the aquatic fauna, the fishing legislation, originally focused on the migratory species, became obsolete. The current defense period, which determines the temporary suspension of fishing activities, for example, is totally contested by fishermen and by segments of the organized society. The current local structure, which received support from the GEF São Francisco Project, for its consolidation, corresponds only to part of the required infrastructure for implementing the ichthyofauna reconstitution program. It is necessary further suport, so that the involved institutions, particularly the IBAMA, take over the continuity of the actions, assuring its sustainability. Two strategic actions are recommended here, aiming at rationalization of the fishing and preservation of the biodiversity. Those actions are planned for a 3-year period.
Action I – Re-populating (stocking native species, from laboratory reproduction and/or acquisition of young fish, from other institutions) Methodology: • Forming a breeding stock and acquisition of young fish of native species; • Identifying and selecting re-populating sites; • Limnologic monitoring; • A dissemination program for the riverine communities and fishermen colonies/associations; • Re-populating; • Monitoring of fish disembarkment.
Action II – Implementing a Fish Disembarkment Control System. Methodology: • Reconnoissance of the Municipalities/Locations; • Meeting with local leaders; • Selecting the sites for continuous data collection on fish disembarkment; • Selection of data collection personnel, among the local guides; • Preparing Structural Census Forms; • Preparing Disembarkment Control Forms; • Data coding, typing and processing; • Spreading out the results.
lx Total Cost of the Program
Discrimination total (US$)
Estimated costs for the donor institution 214,100
Institution’s counterpart 470,500
Global Cost 684,600
10.2. AQUICULTURE INCENTIVE PROGRAM Fishing production in the Lower São Francisco has been decreasing in the past years. The total production disembarked in eight Municipalities, in 1999, presented a 12.8% reduction, in comparison with 1998. The fishermen perceive, for at least a decade, the “time of the river” is no longer associated or marked by the great floods that regulate fishing. Handcraft fishing, considered as a source of food and support for the fishermen, is far from representing a sustainable future. There are diverse and multiple economic, ecological and cultural pressures on the activity, what affects enormously its maintainance. The resulting adverse impacts, mainly due to the dams, particularly on the ichthyofauna, has been cutting on the fishing stocks of authoctone migratory species of commercial value. For this reason, preservation of the resources demands the adoption of more intense management programs. And, to overcome the problem, several innitiatives have been presented, with especial emphasis to the incorporation of aquiculture to the activities of the handcraft fisherman, which would turn him into an aquicultor. The Xingó Technologic and Scientific Development Institute, in partnership with CODEVASF, has been developing works in several communities, to promote the use of fish tanks in pisciculture. Financial complementary support will permit the incorporation of skills and meanings that are still away from the traditional fisherman’s culture. Additionally, it will strengthen initiatives related to social organization and to a better structures associativism.
Methodology • Setting up aquiculture production demonstrative units, as tools for validating the production process and spreading out the technology; • Preparing and offering courses on fish production in cages, on quality principles, and on the control of fish processing, transportation and trade, as well as on associativism and cooperativism. • Preparing guidelines for training the handcraft fishermen on the use of fish cages.
lxi Total Cost of the Program
discrimination TOTAL (US$)
Estimated costs for the donor institution 49,000
Institution’s counterpart 470,500
Global cost 519,500
10.3. CREATION OF TWO SUPPORT CENTERS FOR THE FISHERMEN (PENEDO AND PRÓPRIA) Objectives • Centralize all information necessary for the sustainable management of the fishing (creation of many Help Boxes for the fishermen: INSS, IBAMA, Ministry of Agriculture, Ministry of Justice, Navy). • Creating an space for a permanent participative management forum, where universities, Federal, State and Municipal agencies may discuss, jointly, and contribute to the solution of existing problems. • Creation of an information center, for training the sons of fishermen and capacitating the colonies in the use of computer data. • Setting up permanent public fishing expositions (fish, fishing strategies, innovations, etc.) and other activities (bring fishermen to give out lectures, for example). • Setting up exhibition rooms for artcrafts produced by the fishermen’s women (laces, pottery, etc.). • Implementing workshops related to the making of fishing equipment, where the Elder would teach the younger fishermen. Proposal of Activities • Implementation of workshops and trainings on Participative Research Methodology and on Community Planning. UFAL is a co-proponent of the Brazil-Canada bi-lateral Project on “Interior Fishing in Brazil: Conservation and Participative Management”. • 20-hour course for capacitating communities to participate in the management process. • Preparing a didactic book on fishing in the Lower São Francisco, aiming at adding value to the fishermen’s culture in the educational network, at elementary level.
Estimated Costs for Creating the two Fishermen’s Support Centers
lxii The creation of the two centers requires partnership with the local Prefectures (Penedo e Piranhas), that might donate the area for the construction.
Estimated Costs for Building the two Centers:
discrimination total (US$)
Estimated costs for the donor institution 60,000
Institution’s counterpart 200,000
Global costs 260,000
10.4. PREPARING THE DIDACTIC BOOK FOR THE EDUCATIONAL NETWORK Objective • Transform the results of published works on the fishing on the Lower São Francisco, in diverse áreas (socio-economical, ethnological, ecological, geological, etc.), into texts aimed at each level of the elementary schools. The objective is to insert “fishhing in the São Francisco” as a transversal topic, up for discussion in all disciplines. Proposal of Activities • Survey of existing publications and creation of a data base; • 2-month course on “Fishermen’s Right”, aimed at students (Biology, Law, Sociology, Pedagogy, etc.). • Preparation of the didactic book, compliant with the National Curriculum Parameters, including discussions of the texts with a pedagogue. • Scheduling meetings with the Fishermen Colonies, teaching establishments in the Lower São Francisco and those with interests on the work. • Training local instructors, for reading the texts, making suggestions and reviewing documents. • Organizing the tests and using the material in a pilot school (500 copies). • Publishing a preliminary version of the books.
Estimated Costs of the Book for the Elementary Educational Network The idea is to add value to the fishermen‘s culture, restoring their ethnoecological knowledge about fish, crustaceans and the environment, and use it in association with a scientific understanding, in the elementary school disciplines.
lxiii With a vast material already collected, the book would be prepared by a multidisciplinary team, composed of students of pedagogy, biology and social sciences, with scholarships. The Project is to be implemented in six months.
Estimated Costs for Preparing the Book:
Discrimination Total (US$)
Estimated costs for the donor institution 36,500
Institution’s counterpart 200,000
Global cost 236,500
lxiv