INLAND FISHERIES: PAST, PRESENT AND FUTURE.
1950 1953 1956 1959 1962 1965 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004 2007 2010 Catch (tonnes 10 6 ) Inland fish catch by year 1950 2012 Based on FAO Statistics 14 12 10 8 6 4 2 Quantity (tonnes) Asia - Inland waters Africa - Inland waters America, South - Inland waters Europe - Inland waters America, North - Inland waters Oceania - Inland waters Former USSR area - Inland waters 0 Year
Recreational fisheries Recreational fishermen Match fishermen Specimen fishermen Removal fisheries Catch and return Put and take fisheries Changing patterns away from rural fishing to urban put and take 6 billion UK 25 billion Europe (2004) $ Canada 8.3 billion $ 34 billion USA Concealed subsistence fisheries Growing importance in countries such as Brazil, Argentine, South Africa
The Capitoline sturgeon
Mills and fisheries listed in the UK Domesday Book 1086 River Thames
If you take a stick and stir well The good old River Irwell Sick of this occupation you will very soon become Cos foetid bubbles rise and burst And really this is not the worst For little birds can hop about dry footed on the scum
Eutrophication oligotrophic mesotrophic eutrophic hypereutrophic P concentration 10-12 12-24 24-96 96 Increased biomass of phytoplankton Toxic or inedible phytoplankton species Increases in blooms of gelatinous zooplankton Increased biomass of benthic and epiphytic algae Changes in macrophyte Decreases in water transparency (increased turbidity) Colour, smell, and water treatment problems Dissolved oxygen depletion Increased incidences of fish kills Loss of desirable fish species Reductions in harvestable fish and shellfish Decreases in perceived aesthetic value of the water body or river Eutrophication downstream occurs as part of the natural processes in rivers
Historical changes to the Rhine 1828 1872 1963
Location of international and bilateral inland fisheries projects in Africa 1970-1990 Niger Central Delta Senegal R. Gambia R. Niger R. Niger L. Kossou Volta L. Oueme R. L. Kainji L. Chad Chari Logone R. L. Nasser/Nubia L. Victoria Rivers L. Victoria L. Kivu L. Tanganyika L. Mweru/ L. Bangweulu L. Malawi Kafue R. L. Kariba Barotse floodplains
Migration patterns of river fish A Longitudinal migration in river channel with downstream drift of fry (whitefish pattern) B Lateral migration of adults and fry to floodplain C Migrations of adult fish into and out of tributaries D Lateral migrations between main river channel and floodplain lakes E Lateral migrations from floodplain lakes onto floodplain (blackfish pattern) F Migrations of adult to spawn at river margin with movements of fry onto floodplain and return movement of young-of-the-year to main channel (grey fish pattern) G Internal movements within lakes H Anadromous/catadromous migrations into system from the sea
Catch (t) Indexes of catch Lakes Mei = Conductivity/mean depth Rivers Basin area main channel length 90000 80000 70000 60000 50000 40000 30000 20000 10000 0 0 1000000 2000000 3000000 4000000 5000000 Basin area (km2)
Relationship between area of floodplain area flooded and catch. Catch of fish in same year or following years depending on size and age of fish caught Area of floodplain flooded
River continuum and flood pulse concepts River continuum Serial degradation of organic material entering system upstream by invertebrates as matter moves downstream Coarse organic matter Fine particulate organic matter Very fine particulate organic matter Flood pulse River channel Floodplain Ultrafine particulate organic matter Mobilisation of nutrients during flood events creates rich environment on floodplain
Catch The fishing down process Large, long-lived species and individual fish Small, short-lived species and individual fish Effort
Number of species Number of species recorded as being caught in FAO statistics 1950-2012 450 400 350 300 250 200 150 100 50 0 Year
Yield (kg/ha) Yield from stocked reservoirs of different areas 400.00 350.00 300.00 250.00 Mexican reservoirs Y = 131664D -0.7475 r 2 = 0.3769 200.00 150.00 100.00 50.00 1400 1200 1000 800 600 400 200 0 S.E Asia - Thailand and Vietnam y = 2210.5x -0.496 R² = 0.7363 0 10000 20000 30000 40000 50000 Area (ha) 0.00 0 20000 40000 60000 80000 100000 120000 140000 Area (Ha) 1800 Chinese reservoirs 1600 Y = 4188.1D -0.3746 1400 r 2 = 0.9562 1200 1000 800 600 400 200 0 0 5000 10000 15000 20000 25000 30000 35000 40000 Area (ha) 120 100 80 60 Sri Lankan reservoirs Y = 10329D -1.0251 r 2 = 0.3016 40 20 0 0 1000 2000 3000 4000 5000 6000 7000 Area (ha)
Functions for governance at various administrative levels Fishermen groups, landing committees, lake management committees District authorities; lake or river management committees Regulate access, effort, closed seasons, permissible gear. Collect catch data Set local objectives for river or lake. Negotiate environmental conditions Set up local reserves Central Government Devolve authority and supervise day-to-day management Set overall objectives for fisheries Negotiate agreements on water quality and quantity between users Fisheries Research Interpret and report national statistics. Establish and oversee national parks and reserves. International lake or river International conservation agreements basin commissions International conservation International collaboration. organizations International conservation agreements
Ln Species richness (No of species) Ln Species richness (No of species) Number of species by river and lake basin area 6 (a) 4 Ln River basin area (Km 2) 2 0 3 6 9 12 Ln Lake area (Km 2 )
1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 yield (tones x 10 6 ) Inland and brackish water aquaculture production 1950-2012 50 45 40 35 30 25 20 15 10 5 0 Brackishwater Freshwater TOTAL year
Intensity of human inputs Yields from various types of culture and enhancement Raceways Cages Completely fed and aerated ponds Fertilized and fed ponds Fertilized ponds Brush parks and pens Heavily stocked fertilized(2000-3000/ha) Extensive stocked unfertilized (500-2000/ha) Natural production with stocking (<500/ha) Natural production with removal of predators Tropical natural production Warm temperate natural production Cold temperate natural production 1 10 1 10 2 10 3 10 4 10 5 10 6 Yield kg/ha/y