General Article: Lake Victoria & Area

Domino Effect Disaster

by Brad Harrison

Lake Victoria a.k.a. Lake Nyanza is the second largest body of freshwater in the entire world. It covers 26,828 square miles (69,484 square kilometers). Eastern African countries of Kenya, Tanzania, and Uganda border it.

For quite some time now scientists and ecologists have flocked to study the endemic cichlids for their evolutionary capabilities. It is believed that as little as 14,000 years more than 400 species of cichlids have evolved from only 5 species of ancestors. This evolutionary process would probably stagger the mind of the well-known evolutionist Charles Darwin.

Unfortunately this wondrous body of water that was once filled with some of the most beautifully colored freshwater species on the planet, described as Darwin?s Dreampond, is now highly threatened by the inevitable tinkering of man and his by-products.

From my research ascertained during extensive web and print related reading, I must conclude that the beginning of this catastrophe came shortly after John Speke, a British explorer, discovered the lake in 1858. He then aptly named the lake after Queen Victoria.

The Agricultural Threat

Only a few decades later the exploitation began. Early settlers promptly began clearing the natural vegetation and draining the surrounding swamps in order to farm cash crops such as coffee, tea, and sugar. Over the years these plantations have grown in size and numbers. Agricultural chemicals such as fertilizers began draining into the lake during the rainy seasons, which have caused an explosion of algae blooms and overgrowths of water hyacinth. This has in turn decreased oxygen levels in the lake to dangerous life-threatening levels.

The Population Pressures

The boom in agriculture soon attracted masses of migrant workers to work the fields. These workers quickly settled into areas surrounding the lake and can now be considered the forefathers of what is now considered to be one of the fastest growing populations in the world. An estimated 25 million people now call the three surrounding countries home.

Of course with any population this large there must be an infrastructure of industry to support it. Soon industries such as paper mills, breweries, textile mills, and leather tanning began dumping their waste into the once pristine waters. Untreated sewage is also being dumped. In fact one source that I read charged one of the surrounding countries (Tanzania) with dumping two million liters of untreated sewage daily.

The Over Fishing

For such a large population a viable food source must be found. For this they soon turned towards the abundant (or so they thought) populations of cichlids.

These once abundant cichlids proved to be a good source of protein-rich food for the surrounding populations, and were easily caught using crude and inexpensive fishing methods. Unfortunately by the early 1950s, most of the most popular food species such as the Oreochromis esculentus rapidly decreased in numbers.

The Species Introduction

In order to combat the coming food shortage, the British officials charged with the care-taking of their budding colonies unleashed one of the biggest ecological disasters of our time.

It was decided that they should introduce two species of fishes in order to offset the depletion of the endemic cichlids. One was to be the Nile tilapia (Oreochromis niloticus). Due to its relatively small size of 10 to 20 pounds it was immediately sought as a food source as it required little more than the normal crude equipment to catch and prepare. The second species introduced proved to be disastrous.

The Nile perch (Lates niloticus), at a maximum size of 600 pounds, was initially thought to be an extremely viable food source. But as fate would have it the local fishermen paid it little attention, as it required much more expensive fishing equipment and larger boats to haul in this behemoth from the much deeper waters that it preferred.

The Nile perch, with its gigantic size and voracious appetite to match, soon began to decimate the already threatened populations of cichlids and their food sources. With no natural predator to control the populations besides man, they even began feeding upon smaller examples of their own species.

The Numbers

The latest numbers available to me demonstrate the crushing blow of man's impact on Lake Victoria. The once richly diverse population of more than 400 species has been cut down to roughly 200 due in large part to the Nile perch. In fact it is believed that there were several species made extinct before classification was possible.

When introduced, the Nile perch made up a minute percentage of the biomass of Lake Victoria, but in 1980 a study produced shocking results. The scales had been tipped to indigenous cichlid species making up only 1% of biomass while the Nile perch had jumped to an alarming 80%.

In Conclusion

Although I had knowledge of the problems of Lake Victoria when I started to write this article, I was truly shocked when I started reading all of the sources of hard data I had read in order to give what I hope to a simplified yet informative article on the plight of the home waters to my beloved Viccies. I'm in fact more determined than ever to keep my strains true, not only to species type but region if at all possible. I hope that after reading this you will try to do the same. The day may come that some of these special cichlids that we keep in our homes and public aquariums will be the last examples available.

Article and Images Copyright ©2000 by Brad Harrison, all rights reserved.

 



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