Reconciling Human Needs and Conserving Biodiversity: Large Landscapes as a New Conservation Paradigm by Bila-Isia Inogwabini

Author:Bila-Isia Inogwabini
Language: eng
Format: epub
ISBN: 9783030387280
Publisher: Springer International Publishing

16.3 Fish Species Diversity in the Rivers and Lakes of the Lake Tumba Landscape

Characteristic species of the area of the Mid-Congo River include Protopterus dolloi, Hydrocyon vittiger, Hydrocyon goliath, Hydrocyon vittatus, Phractolaemus ansorgii, Ctenopoma fasciolata, Channa obscurus, Lates niloticus, Claria buthupogon, Synodontis nigriventris, Auchenogianus punctatus, Schilbe marmoratus, etc. (Banister 1986; Chapman 2001). The fish diversity in the Lake Tumba, as it the case for many water bodies in the Democratic Republic of Congo, is still subject to variations. Past research documentations have been quoting different figures, varying from 67 species (Marlier 1958) of 86 fish species (e.g. Aveling et al. 2003) present in the Lake Tumba Landscape but that has been reduced down to 30 species (Inogwabini and Lingopa 2006). Reasons for these reductions are difficult to ascertain for the time being because of some changes in the nomenclatures of species, which have been changing over years. Also, despite some species previously not being currently observed, it would be difficult to conclude their local extinction since proof of extinction would take dozens of years to be confirmed. Indeed, some species were collapsed into families and species from which they were previously distinguished. This reality is not singular to Lake Tumba, however; it does emphasize the need for more updated research in the region as well as in the country. Despite these changes, however, most common species of the Lake Tumba, which remain constant over different reporting periods, are: Auchenoglianis occidentalis, Clarotes laticeps, Gephyloglianis congicus, Claria buthopogon, Distichodus, Channa obscurus etc. (Corsi 1984b).

The figure of 41 fish species has been quoted by Corsi (1984b) for Lake Maindombe, of which three endemics but, as it is the case for many areas in this zone that is characterized by being poorly known (Schliewen and Stiassny 2006), Kutshukina and Micha (2013) reported more than fifty fish species in a market study from the same lake. Apart from the widely spread species of Clariidae (Clarias angolensis, Clarias gabonensis, etc.), other frequently encountered species that were listed by Kutshukina and Micha (2013) include Auchenoglanis occidentalis, Gephyroglanis congicus, Synodontis ornatipinnis, Distichodus fasciolatus, and Mormyrops nigricans. As it was the case for Lake Tumba and as it discussed in the section of threats to freshwater in this chapter, reports are that fish stocks have decreased over the last decades. Decreasing fish stocks can be captured from surrogate methods; in the case of Lake Maindombe, the situation can be depicted by the fact that nets with smaller mesh sizes are wildly and widely used. Indeed, Kutshukina and Micha (2013) found that nets of greater than or equal to 2 mm and 2–2.5 mm mesh sizes had been used in higher frequencies (respectively 32% and 38%). Nets of small mesh sizes, particularly of the range 1–2.0 mm, are often used when catches per unit effort are low and cause depletion in fish stocks as they would literally comb any species regardless of the age and the size of the fish.

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