Pollution and overfishing have decimated Nile fish stocks.
The vast majority of Egypt’s 80 million inhabitants live along the banks of the Nile. The river, which enters the country near the southern city of Aswan, flows 1,300 kilometres before emptying into the Mediterranean Sea near Alexandria.
“You can drink the Nile near Aswan, but by the time the water reaches Cairo it is heavily polluted,” says Sherif Sadek, a former fisheries official. “Some species could not tolerate the polluted water and are no longer found in the river.”
A report issued by Egypt’s environment ministry in September [2009] identified three main sources of Nile pollution as untreated sewage, agricultural drainage, and industrial effluents. It said the country produces an estimated 12 million cubic metres of wastewater a day, of which a large portion is discharged into the Nile.
“Domestic wastewater collected from approximately 5,000 basins in small remote villages (is) directly discharged into agricultural drains without treatment, in addition to the untreated or secondary treated sewage from sanitation networks of major cities,” the report says.
Agricultural run-off, including an unspecified amount of fertilisers and pesticides, enters the Nile through 75 major drainages, according to the report. Over 100 industrial complexes discharge a total of four billion cubic metres of effluents into the river each year. Other sources of pollution include houseboats and thousands of motorised river vessels.
While authorities who monitor the river insist that pollution levels are within permissible limits, many Egyptians are concerned about the effect of contaminants on the river’s fish.
“The river is basically Egypt’s sewer and I wouldn’t eat anything living in it,” says Mona Radwan, a marketing agent who lives in an upscale Cairo neighbourhood. “Many Egyptians eat fish from the Nile because they are too poor to afford meat or chicken.”
Experts say it is important to differentiate between organic and inorganic pollutants.
“With human waste, the principal concern is parasite and disease cycles, but I don’t think there’s much evidence to show that fish feeding (on sewage) pose a risk to human health, particularly if the fish are cooked properly before they are eaten,” says Malcolm Beveridge of the Malaysia-based WorldFish Centre. “A bigger concern might be industrial and agricultural wastes, especially heavy metals and toxic pesticides.”
Among the highest at risk are the 15,000 fishermen who drink, bathe in, and eat fish from the Nile. Many suffer from kidney problems, skin irritations and bilharzia, a water-borne parasite.
The consensus among fishermen is that the Nile’s fish stocks are declining. Officials, however, insist the river’s productivity is higher than ever. They argue that the perception of a declining fish population is due to the increasing number of fishers competing for resources, and localised pockets of overfishing near urban centres.
Beveridge says the Nile’s fish population declined sharply after completion of the Aswan High Dam in the 1960s, but has rebounded in recent years.
“Studies have shown that fish production collapsed in the second half of the 1960s, because the dam trapped organically rich sediment that the delta, and indeed large areas of the eastern Mediterranean, were dependent upon for fish productivity,” he told IPS.
“But then something very peculiar happened. In the 1980s fish production began to increase again, and today yields are higher than they were before the high dam’s construction.”
A team of U.S. and Egyptian researchers found that the massive dumping of sewage and fertilisers into the river had increased concentrations of nitrogen and phosphorous in the water, stimulating fish growth. In a study published last January in the Proceedings of the National Academy of Sciences, they concluded that these anthropogenic nutrients had offset the river’s organic nutrient loss, contributing to a three-fold increase in fish landings over pre- dam levels.
While the research was based on fisheries of the Nile delta’s coastal waters, its conclusions have been extrapolated to the river itself. Artificial nutrient enrichment may have inadvertently reversed declining fish stocks, but the study’s authors warn that pollution is not a solution.
“Some preliminary evidence indicates that increasing nutrient loads may stimulate (fish) landings up to a point, beyond which the fisheries decline due to poor water quality or overfishing,” they say.
Source: Cam McGrath, IPS, 31 Dec 2009
