Crayfish introduction to the Nile Delta and its effects

Crayfish are fresh water crustacean that look like a tiny lobster, to which they are closely related. Out of 250 species in the South-East United States, the species Procambarus clarkii, known as Louisiana red swamp crayfish, is the most well known.In places like Louisiana it is farmed commercially and consumed in various dishes.

This species is very invasive and takes over any place it has been introduced into, such as in Washington State, Spain, and elsewhere.

Crayfish introduced into the Nile

Crayfish has found its way to the Nile via an unfortunate mishap. Someone who has a shrimp farm in Al-Qanater imported the crayfish from the USA, thinking they are a kind of prawn. However, they ate their way through the mud paritions, destroying all the other tanks. What does the shrimp farm owner do? He gets rid of the pests by releasing them into the Nile!

Distribution of Crayfish in the Nile

A recent study has shown that the entire delta is infested with crayfish after the above mishap. The crayfish have not yet made its way south of the delta, stopping at Bani Sweif.

Safety for human consumption

Crayfish is a cheap source of protein and seafood. Similar to the much more expensive shrimp and lobster, but much less in price compared to them. Due to their relatively short life span, and the fact that they lose the accumulated heavy metal and chemicals when the moult, they are relatively pollutant free.

However, a study by two Egyptians have found an alarming percentage (46%) was not suitable for human consumption, due to Enterobacters, and E. coli.

When I ate crayfish in Alexandria, I noticed that they did not taste as good as shrimp or crabs, as I expected them.

Possible cure for Schistosoma/Bilharzia

Due to the predatory nature of crayfish, and their voracious appetite, they have been introduced in some places (e.g. Kenya) to limit the number of snails that act as an intermediate host for Schistosoma, a disease that afflicts some 12 million Egyptians, and claiming the lives of many.

There are hopes that this accidental introduction may be a mixed blessing for Egyptians, and would be a safer means of controlling snails, in lieu of copper sulfate or other chemical agents.

Pictures of Crayfish

The following set of pictures are of crayfish from various countries.

This is a female crayfish from Belwood Lake, in Ontario, Canada. Notice how she is bending its tail to protect its soft eggs.

This is a frontal view of the same female crayfish from Belwood Lake, Ontario, Canada.

This is a crayfish swimming in Bahr Mouweiss, a canal in Zagazig, El Sharqeyya, Egypt.

Another picture in Bahr Mouweiss of a crayfish. Note the burrow on the left.

These are crayfish for sale in El Meidan market in old Alexandria. They are quite cheap, and not much in demand it seems.

This is some of the above crayfish from El Meidan market after being cooked in traditional Alexandine Egyptian style.

A closeup of cooked crayfish.

Another closeup of cooked crayfish.

A closeup of a large cooked crayfish.

Links and Resources

• Procambarus clarkii, Louisiana red swamp crayfish.
• Al Ahram Weekly: Issue 659, 9-15 October 2003: Not just ugly.
• Al Ahram Weekly: Issue 780, 2-8 February 2006: Small Jaws.
• A paper by Elmossalmai and Emara on Safety and quality of freshwater crayfish Procambarus clarkii in the river Nile.
• A paper on the distribution of crayfish in the Nile delta.
• A paper on the Impact of the crayfish Procambarus clarkii on Schistosoma haematobium transmission in Kenya.
• A paper on the Assessment of Cadmium and Lead in water, sediment and different organs of Procambarus clarkii in the River Nile.