Fishermen on the Nile, from our Apartment, Cairo, Egypt
Many varieties of fish are found in the Nile system. Notable among those found in the lower Nile system are the Nile perch (which may attain a weight of more than 175 pounds), the bolti (a species of Tilapia), the barbel, several species of catfish, the elephant-snout fish, and the tigerfish, or water leopard.
However, prospects for Nile fishermen are not promising. Many schools of fish that fed in the waters of the Nile in Egypt during the flood season have been reduced or have disappeared since the construction of the Aswan High Dam. Most of the species of the Nile fish were migrants, and the dam has prevented many from migrating to Lake Nasser. The diminution in the number of anchovies in the eastern Mediterranean has also been attributed to the serious reduction in the outflow of waterborne nutrients due to the dam.
Almost half of the Nile fish depicted in ancient reliefs are now extinct from Egyptian waters. Researchers comparing historic fish collection records estimate that as many as 35 of these fish species, including the elephant fish, Nile jewel cichlid, and African bony tongue, disappeared from the lower reaches of the Nile in the last 40 years. Dozens more are listed as threatened or endangered.
Justin Grubich, assistant professor of biology at the American University in Cairo, says Nile river fisheries suffered a catastrophic decline following the construction of the Aswan High Dam in the 1960s. The dam acts as a barrier, impeding the reproductive cycle and migratory routes of many fish species, and preventing millions of tonnes of silt and organic matter from reaching the lower Nile.
“The High Dam was built to control the flood season so as to have more consistent agriculture,” Grubich explains. “The dam helps regulate water better, but downstream there is no replenishment of soil and nutrients (to support aquatic life).”
The impact is felt over 1,200 kilometres downstream. Without sedimentation, the Nile delta is receding, in some areas by several metres a year.
The coastal erosion has allowed the sea to advance into a series of shallow lakes at the mouth of the Nile, killing freshwater species unable to tolerate the higher salinity. It has also allowed predatory marine fish to invade spawning and nursery areas, devastating fish stocks.
Research conducted in the 1970s found that aquatic biodiversity in the four Nile-fed Delta lakes in Egypt had decreased significantly. Surveys by the National Institute of Oceanography and Fisheries (NIOF) identified 34 species of fish in Lake Manzala, compared to more than 50 recorded half a century earlier. Similar patterns were found in nearby Lake Burullus, which had become exceedingly brackish.
And polluted. Over 4.5 million tonnes of industrial effluent, including 50,000 tonnes of hazardous contaminants, is poured into the lower Nile each year, according to the environment ministry. The pollution, which also includes agricultural runoff and untreated sewage, poisons aquatic life in the river and concentrates in the lakes at its mouth.
Juvenile fish are extremely susceptible to pollution, which can kill them directly, “or create a large volume of decaying organic matter that uses up all the dissolved oxygen that fish need to survive,” says Osman El-Rayis, professor of chemistry at Alexandria University.
Lethal levels of water toxins may have already extirpated the jewelfish, which once flourished in the Nile delta and northern lakes. Fishermen say the plump, bottom-scouring moon fish is now rarely seen in the river. And the once ubiquitous Nile minnow, which moved in large schools in the shallows, is now restricted to a few locations near Aswan.
Fishermen on the Nile, from our Apartment, Cairo, Egypt
Many varieties of fish are found in the Nile system. Notable among those found in the lower Nile system are the Nile perch (which may attain a weight of more than 175 pounds), the bolti (a species of Tilapia), the barbel, several species of catfish, the elephant-snout fish, and the tigerfish, or water leopard.
However, prospects for Nile fishermen are not promising. Many schools of fish that fed in the waters of the Nile in Egypt during the flood season have been reduced or have disappeared since the construction of the Aswan High Dam. Most of the species of the Nile fish were migrants, and the dam has prevented many from migrating to Lake Nasser. The diminution in the number of anchovies in the eastern Mediterranean has also been attributed to the serious reduction in the outflow of waterborne nutrients due to the dam.
Almost half of the Nile fish depicted in ancient reliefs are now extinct from Egyptian waters. Researchers comparing historic fish collection records estimate that as many as 35 of these fish species, including the elephant fish, Nile jewel cichlid, and African bony tongue, disappeared from the lower reaches of the Nile in the last 40 years. Dozens more are listed as threatened or endangered.
Justin Grubich, assistant professor of biology at the American University in Cairo, says Nile river fisheries suffered a catastrophic decline following the construction of the Aswan High Dam in the 1960s. The dam acts as a barrier, impeding the reproductive cycle and migratory routes of many fish species, and preventing millions of tonnes of silt and organic matter from reaching the lower Nile.
“The High Dam was built to control the flood season so as to have more consistent agriculture,” Grubich explains. “The dam helps regulate water better, but downstream there is no replenishment of soil and nutrients (to support aquatic life).”
The impact is felt over 1,200 kilometres downstream. Without sedimentation, the Nile delta is receding, in some areas by several metres a year.
The coastal erosion has allowed the sea to advance into a series of shallow lakes at the mouth of the Nile, killing freshwater species unable to tolerate the higher salinity. It has also allowed predatory marine fish to invade spawning and nursery areas, devastating fish stocks.
Research conducted in the 1970s found that aquatic biodiversity in the four Nile-fed Delta lakes in Egypt had decreased significantly. Surveys by the National Institute of Oceanography and Fisheries (NIOF) identified 34 species of fish in Lake Manzala, compared to more than 50 recorded half a century earlier. Similar patterns were found in nearby Lake Burullus, which had become exceedingly brackish.
And polluted. Over 4.5 million tonnes of industrial effluent, including 50,000 tonnes of hazardous contaminants, is poured into the lower Nile each year, according to the environment ministry. The pollution, which also includes agricultural runoff and untreated sewage, poisons aquatic life in the river and concentrates in the lakes at its mouth.
Juvenile fish are extremely susceptible to pollution, which can kill them directly, “or create a large volume of decaying organic matter that uses up all the dissolved oxygen that fish need to survive,” says Osman El-Rayis, professor of chemistry at Alexandria University.
Lethal levels of water toxins may have already extirpated the jewelfish, which once flourished in the Nile delta and northern lakes. Fishermen say the plump, bottom-scouring moon fish is now rarely seen in the river. And the once ubiquitous Nile minnow, which moved in large schools in the shallows, is now restricted to a few locations near Aswan.