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Minho River PORTUGAL

Minho River PORTUGAL. Carlos Antunes, Alfredo Oliveira, Sérgia Costa Dias Centre for Marine and Environmental Research (CIIMAR) –University of Porto. Geographical location. International river: Spain and Portugal River spring: Spain, at “serra de Meira”, 750 m altitude.

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Minho River PORTUGAL

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  1. Minho River PORTUGAL Carlos Antunes, Alfredo Oliveira, Sérgia Costa Dias Centre for Marine and Environmental Research (CIIMAR) –University of Porto

  2. Geographical location International river: Spain and Portugal River spring: Spain, at “serra de Meira”, 750 m altitude. Course: 300 km, the first 230 km in Spain. The final 70 km are the border between Portugal and Spain. Basin limit Border

  3. Basin limit Border Minho River Basin: Physical caracteristics Catchment area (total): 17 080 km2 International sub-basin area: 1 934 km2 Catchment area in Spain: 16 250 km2 Catchment area in Portugal: 800 km2 Total surface water area: 800 km2 Min. monthly discharge (August 1976): 31 260 dam3 Max. yearly discharge (January 2001): 5 673 972 dam3 Mean monthly discharge (Oct.1973-April 04): 834 615 dam3 (50 Km upstream the mouth of the river) Estuary length: 30 Km Temperature: 9.6ºC (Jan.) – 20.4ºC(Aug.) Salinity: 0.1ups – 34.64 ups (Year reference: 2000)

  4. 8 7 3 6 1 5 2 4 9 10 Minho River Basin: Main tributaries The Minho catchment's area is characterized by the existence of two main rivers, the Minho river and his main tributary, the Sil river. The source of the Sil river is located at 1500 m of altitude in “serra de Jistreda”, in the Cantabrian Mountains. The Sil flows through 226 km, and joins Minho river at 70 km before the beginning of the international stretch. The Sil sub-basin covers an area of 8 000 km², i.e., about 50% of the total of Minho‘s drainage basin.

  5. Minho River Basin Images Basin limit Border

  6. ENVIRONMENTAL CONSTRAINTS Dams Dam locations in Minho catchment area Basin limit Border

  7. ENVIRONMENTAL CONSTRAINTS Dams Dams affecting upstream migration Basin limit Border Basin limit Border

  8. ENVIRONMENTAL CONSTRAINTS Point source pollution Non-point source pollution LugoUrban PonferradaIndustrial and Urban OrenseUrban Rio BarbañaIndustrial Rio LouroIndustrial Basin limit Border VN CerveiraIndustrial In: Antello et al., 1998 Norton, R., 1998

  9. FISHES INTRODUCTION Onchorhynchus mykiss old Micropterus salmoides old Gambusia affinis holbrooki old Carassius auratus old Cobitis calderoni recent Tinca tinca recent Cyprinus carpio recent Gobo gobio recent CRUSTACEA Prochambarus clarkii recent MOLLUSCA recent ENVIRONMENTAL CONSTRAINTS Exotic species Corbicula fluminea Border Basin limit Gobio gobio Micropterus salmoides Cyprinus carpio Prochambarus clarkii Corbicula fluminea

  10. ENVIRONMENTAL CONSTRAINTS ParasiteAnguillicola crassus Basin limit Border

  11. EEL EXPLOITATION Number of fishing licences PORTUGAL In 1984: 1744 In 1989: 820 In 2004: 800 from which 250 were also for glass eel Fishery data declared : 50% of the fishermen Photograph by Eliseo Alonso SPAIN Number of licences : 430 Fishery data declared : 60% of the fishermen

  12. Fishing gears EEL EXPLOITATION Glass eel fishery • Hand-held dip net -“rapeta” • Stow net - “tela” • Use of an illegal stow net called - “tela de saco” NOT ALLOWED IN OTHER NATIONAL RIVERS Yellow eel fishery • Fyke-nets -“nassa” • Baited hooks

  13. EEL EXPLOITATION Fishing gear (glass eel) - “Tela”(stow net) Length of floatline = 10 m; Depth = 8 m; Leadline = 15 m; Meshsize = 1-2 mm

  14. EEL EXPLOITATION Fishing gear (glass eel) - “Tela”(stow net)

  15. EEL EXPLOITATION Illegal fishing gear (glass eel) - “Tela de saco”(stow net with bag) Length of floatline = 14 m; Length of the bag = 10 m; Meshsize = 1-2 mm

  16. EEL EXPLOITATION Fishing gears (yellow eel) - Fyke-nets

  17. GLASS EELS Stow net: O1 Nov. – 30 April Hand dip net: 01 Out. – 30 April EEL EXPLOITATION Fishing regulation YELLOW EELS Fyke-net: 01 Sept.-30 Nov. Baited hooks: All year Length > 20 cm

  18. EEL EXPLOITATION Historical evolution of catches OFFICIAL DATA OF GLASS EEL CATCHES FROM PORTUGAL (P) AND SPAIN (SP) IN THE MINHO RIVER (1974-2003) The data are underestimated.

  19. EEL EXPLOITATION Historical evolution of catches OFFICIAL DATA OF YELLOW EEL CATCHES FROM PORTUGAL IN THE MINHO RIVER (1983-2003) The data are underestimated.

  20. EEL STATUS Area of colonization Basin limit Border In: Hervella & Caballero, 1999

  21. EEL STATUS Accessible and “lost” areas Accessible area 1 934 km2 11% of total catchment area Basin limit Border “Lost” area: 16 250 km2

  22. BIOLOGICAL STUDIES

  23. BIOLOGICAL STUDIES Experimental glass eel fishery

  24. BIOLOGICAL STUDIES Biometric data and pigmentation stages Average length / weight range: 6.3 cm (Jun.) and 7.4cm (Sept.) / 0.17g (Aug.) and 0.380 g (Sept.) Year : 2000 In average in the season fishing: 1 Kg of glass eels = 2800 glass eels

  25. BIOLOGICAL STUDIES By-catch analyses Dias CS & Antunes C, 2004

  26. BIOLOGICAL STUDIES By-catch analyses Dias CS & Antunes C, 2004 • Pisces – 20 species • Crustacea – 20 taxonomic groups • Mollusca – 7 species • Annelida – 1 species • Echinodermata – 1 species Dias CS & Antunes C, 2004

  27. BIOLOGICAL STUDIES Yellow eels (1988) Fyke-nets 0,9 eels/fyke-net/night 4,5 eels/fyke-net/night Basin limit Border 0,2 ind./m2 – 8.8 g/m2 2 ind./m2 – 78.6 g/m2 Electric fishery in small tributaries

  28. BIOLOGICAL STUDIES Parasites Prevalence of Anguillicola crassus (1995/96) 15% 87.5% Basin limit Border

  29. BIOLOGICAL STUDIES Glass eels and leptocephali - otolith microstructure analyses(1991 -1993) Time migration from Sargasso Sea to Minho River 22 – 26 months ? Age estimation dificulty: Difuse Zone LI LII LIII Antunes C & Tesch FW, 1997

  30. ►Management plan adapted to the new local reality: * Fishing licences number control * Fishing period * Fishing area CONSTRAINTS ON THE EVOLUTION OF EEL STOCK ► Lost of habitat► Absence of re-stocking programmes► Habitat quality (?)► Parasites (?)

  31. WORK CARRIED OUT IN 2004/05 • monthly experimental glass eel fishery • biometric and pigmentation stage of glass eels data were registered; environmental data monitoring • analysis of yellow eel abundance by electric fishing in several tributaries of the Portuguese catchment area; we are waiting for permission from the Spanish authorities to sample in up dam areas • sediment quality analysis concerning heavy metals in Minho river estuary • database organization using a Geographical Information System (GIS) to map the Minho river catchment area

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