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The Robust Diversity in West African River Fish

written by: •edited by: Jason C. Chavis•updated: 8/15/2011

The diverse fish population in West African rivers boasts fascinating species from the tiniest fish to the West African manatee. Between freshwater fish to the muddier river spots, the species change along with the watery environment. Hundreds of species can be found throughout West Africa.

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    West African Travels and Discovery

    From December 1894 to November of 1895, a European woman was the first explorer to travel into remote spots of Gabon in West Africa. Mary Henrietta Kingsley went on this exploratory trip to collect various fish and reptiles for use in the British Museum of Natural History in London and to understand fish diversity in the West African rivers.

    Traveling by steamer, she cruised up the Ogooue River to Lamberene, to Talagouga. By canoe, she paddled the rest of the way to the rapids at Ndjole. From there, travel by land took her from the Ogooue to the Remboue River where she boarded a boat to travel to Libreville.

    Hiking Mount Cameroon, a height of 14,435 feet, she finally ended her journey and returned to London. From this adventure, she wrote and published three books: Travels in West Africa, published in 1897; West African Study, published in 1899; and The Story of West Africa, published in 1899. All three books discussed her travels and the Fang people of Gabon. Upon completion, Mary Kingsley grew ill and passed away of typhoid in 1900 with the title of nurse in the Boer War. Kingsley was 38 years of age.

    Kingsley returned with 65 freshwater fish specimens from her exploration of West Africa. Eighteen of these fish were new to Gabon and 7 were new discoveries to science. Her work was incomplete, however she is famed for the contributions she made toward the understanding of the culture and religious customs of the African people.

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    Dominant Species

    After Kingsley passed away, Albert Gunther continued some of her unfinished work, such as recording and naming her found species. He resumed her work in 1896.

    Three species were named after Mary Kingsley. The Brycinus kingsleyae, the Brienomyrus kingsleyae, and the Ctenopoma kingsleyae were all categorized by Gunther in 1896.

    In the rivers of West Africa, especially in the Fatala and Gambia areas, the freshwater species that can be found are mormyrids, characids, featherbacks and the gobies that enjoy the muddy areas of the Fatala especially. Thriving in the West African estuaries and lagoon sections of rivers are the jacks, croakers and mullets.

    The estuaries and lagoons provide the most productive underwater environments due to the algal beds and coral reefs. With the abundance of algae and coral, higher populations of fish cling to the area for food sources. The more saline zones, such as the estuaries where salt water meets freshwater, both adults and fry thrive. The brackish waters attract several species and provide a healthy environment for breeding. Cluepids are dominant by numbers ranging from 61% to 85% in these areas.

    Found in the Sine-Saloum estuary, the dominant species is the Ethmalosa fimbriata. In Gambia, two species live in higher numbers, such as the Sardinella maderensis and the east fimbriata. The Fatala estuary in Guinea is the ilisha africana and the ethmalosa fimbriata and are higher in population.

    Senegalese estuaries house catfishes and croakers by the mouth of the river, replacing them with clupeids and mullets toward the center of the river, once again, as the environment of the river changes, so do the species.

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    Recent Studies

    In more recent years, a team of participants called the “Mary Kingsley Centennial Exploration of Gabon’s Freshwater Fish Biodiversity" group, traveled to West Africa to take a look at Kingsley’s findings.

    On the equator of the west coast of Africa, the territory is filled with dense rainforest left intact. This is especially true in the northeastern Gabon region. The Ogooue River is the main watershed and is the second largest river in Central West Africa. Fed by various important rivers, such as the Ivindo, it is home to numerous endemic species. As many as 30% of the freshwater species of fish are endemic to this province.

    The team studied the aquatic life in the area in 1998, capturing photographs, skin samples, fish samples and many net samples to find if the fish species were still thriving in the rivers just as Mary Kingsley located them in her time. They found the species named after the explorer of earlier years and examined many more while there.

    From the Ivindo river net samples, fish such as marcusenius conicephalus, marcusenius moorii, petrocephalus simus, pollimyrus marchei, and brienomyrus hopkinsi were existing in the environment with healthy looking samples caught in the net, all falling under the mormyrid family of fishes. The species of fish caught were toward the surface, rather than bottom feeders.

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    Specific River Species

    For a listing of specific rivers in West Africa and the fish that thrive in them, a compilation of listings can be found on Biotope Aquaria. The estuaries and further into the river's center lies a world of various fish species in West Africa. Like other rivers and estuaries around the world, they are falling prey to environmental changes and dangers. Studies and protection programs are in place to alleviate the problems that face the destruction of rivers in this region.

    Manatee looking at the camera Saving aquatic life in the rivers would ensure the safety of species such as the African Manatee, one of the four species of sirenians that is the least studied. The manatees live along coastlines, however are also found in fresh water systems. From the Senegal River to the southern Kwanza River in Angola, including areas of Gambia, Liberia, Guinea-Bissau, Guinea, Sierra Leone, Cote d’lvoire, Ghana, Mali, Nigeria, Cameroon, Gabon, Republic of the Congo and the Democratic Republic of the Congo.

    Manatees of West Africa will occasionally fall prey to crocodiles and sharks, although the biggest threat of diminishing numbers of this beautiful animal is from mankind. Poaching, their habitat loss due to construction and destruction, and various environmental impacts are decreasing the numbers of the rarely studied creature.

    The vegetarian manatee can grow to 14 feet, 9 inches in length and can weigh up to 790 pounds in adulthood. Manatees rely on the vegetation that is on the surface, or barely beneath the surface. Overhanging growth of plants from the banks of rivers make a perfect meal for manatees. In Sierra Leone, manatee tales of theft of fishes from nets and the consumption of rice in huge amounts lend hand to the “pest" title of the manatee. Shell remnants of mollusks have been found in the stomachs of manatees in the Senegal and Gambia areas.

    Hanging out in the coastal areas, estuarine lagoons, in large rivers that are brackish and freshwater, lakes and the farthest reaches of rivers above cataracts, the West African manatee population depends mostly upon the vegetation levels of the region.

    Manatees feed mostly in the night, traveling to and from various feeding spots during the late afternoon or night. Resting during the day, manatees find water that is only about 3 to 6 feet deep to take their naps. Creating very little water disturbance while swimming, the manatee remains one of the quietest of aquatic life in the rivers of the region.

    With very little knowledge about the manatee, the breeding periods of the mammal are unknown, however one calf is born each period. The shallow lagoons are the perfect birthing area. Manatees are usually solitary. Mothers and calves are the primary socialization, however they are found resting in pairs or up to six periodically.

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    Fish Species in West African Rivers

    Fish diversity in West African rivers is solely reliant on the environment and multiple water types that form in one river. With estuaries, brackish fish are found juxtaposed freshwater fish in the center and in the mud-filled, still water areas toward the inner land areas, we find a completely different species listing. Fishing is a large food source for the residents of West Africa, however the area is like every other; under the influences of environmental changes and mankind destruction. Species found in the region today will hopefully be in the waters of West Africa in the future.

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