Slide 1Minho River
Centre for Marine and Environmental Research (CIIMAR) –University of Porto
MINHO RIVER BASIN 1st Seminar INDICANG, Rochefort, 18/05/2005
Geographical location
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
Minho River Basin: Physical caracteristics
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)
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
Estuary length: 30 Km
Temperature: 9.6ºC (Jan.) – 20.4ºC(Aug.)
Salinity: 0.1ups – 34.64 ups
Border
Melhorar estes dados: dados cronológicos; introduzir novo slide com estes dados de caudais;
MINHO RIVER BASIN 1st Seminar INDICANG, Rochefort, 18/05/2005
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.
Minho River Basin: Main tributaries
Spain
Images
Dams
ENVIRONMENTAL CONSTRAINTS
Bassin Limit
Dams
Point source pollution
Norton, R., 1998
Exotic species
Corbicula fluminea
Gobio gobio
Micropterus salmoides
Cyprinus carpio
Corbicula fluminea
Basin limit
Parasite
Number of fishing licences
In 1984: 1744
In 1989: 820
In 2004: 800 from which 250 were also for glass eel
Fishery data declared : 50% of the fishermen
SPAIN
EEL EXPLOITATION
Fishing gears
Use of an illegal stow net called - “tela de saco”
NOT ALLOWED IN OTHER NATIONAL RIVERS
Yellow eel fishery
Fishing gear (glass eel) - “Tela”(stow net)
Length of floatline = 10 m; Depth = 8 m; Leadline = 15 m; Meshsize = 1-2 mm
EEL EXPLOITATION
Fishing gear (glass eel) - “Tela”(stow net)
EEL EXPLOITATION
MINHO RIVER BASIN 1st Seminar INDICANG, Rochefort, 18/05/2005
Length of floatline = 14 m; Length of the bag = 10 m; Meshsize = 1-2 mm
Illegal fishing gear (glass eel) - “Tela de saco”(stow net with bag)
EEL EXPLOITATION
Fishing gears (yellow eel) - Fyke-nets
EEL EXPLOITATION
Fishing regulation
GLASS EELS
Hand dip net: 01 Out. – 30 April
YELLOW EELS
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.
The data are underestimated.
OFFICIAL DATA OF YELLOW EEL CATCHES FROM PORTUGAL IN THE MINHO RIVER (1983-2003)
EEL EXPLOITATION
Area of colonization
Accessible and “lost” areas
"lost" substituir por inacessível
BIOLOGICAL STUDIES
Biometric data and pigmentation stages
1981-1983; 1987-1989; 1991-1993; 2000-2001
By-catch analyses
1988-1991
ICBAS
Estuary
Abundance and distribution of yellow eels, biometric and food regime data
1987-1989
ICBAS
1991-1993
ICBAS
Estuary
Experimental glass eel fishery
outro tipo de gráfico; valor médio por época de pesca;
MINHO RIVER BASIN 1st Seminar INDICANG, Rochefort, 18/05/2005
Biometric data and pigmentation stages
Average length / weight range:
Year : 2000
BIOLOGICAL STUDIES
1 Kg of glass eels = 2800 glass eels
Gráfico1
By-catch analyses
BIOLOGICAL STUDIES
MINHO RIVER BASIN 1st Seminar INDICANG, Rochefort, 18/05/2005
BIOLOGICAL STUDIES
By-catch analyses
Pisces – 20 species
refª cs po sc
Yellow eels (1988)
2 ind./m2 – 78.6 g/m2
0,2 ind./m2 – 8.8 g/m2
Parasites
87.5%
15%
BIOLOGICAL STUDIES
Time migration from Sargasso Sea to Minho River
22 – 26 months ?
366.bin
* Fishing licences number control
Lost of habitat
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
MINHO RIVER BASIN 1st Seminar INDICANG, Rochefort, 18/05/2005
Presences (nº of months)
# 2 species 9 5 9
Isopoda Gnathiidae
Paragnathia formica
Jassa falcata
# 2 species 1 0 1
# 3 species 1 1 1
Crangonidae