The present study on the fish fauna of Bioko reports a total of 43 species of 21 families; 18 of which are new records for the island. Bioko's icthyofauna is made up of 17 freshwater and 26 saltwater and brackish water species. Freshwater fishes are primarily restricted to a narrow belt along the north and west of the island, similar to the adjacent volcanic region around Mount Cameroon. The rest of the island, however, is inhabited by salt tolerant fishes, as found in São Tomé, Príncipe and Annobón. Fish communities also vary according to elevation since rivers on Bioko are characterized by steep gradients from source to sea. Pressures on Bioko's river systems are not alarmingly high but may increase in the future because of the use of toxic products (lime and insecticides) for fishing. There is no doubt that this is having a significant effect on northern and western rivers which are precisely the most species-rich. Aphyosemion oeseri, which is endemic to Bioko, and which has a distribution restricted to the small northern rivers is in great danger of extinction. P. monkei is in a similarly precarious situation, given that it is extremely rare and will probably disappear altogether in a few years from the island's rivers. Before the situation becomes irreversible urgent measures must be taken to improve matters through educational campaigns as well as through cleaning up heavily-polluted rivers and re-stocking them with fish species from neighbouring river basins.
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References
Bauchot, M.L. and Daget, J. (1987) Les Lutjanus des cotes occidentales d'Afrique. Rehabilitation de L. endecacanthus Bleeker 1863 (Peciformes). Bull. Mus. natn. Hist. nat. Paris 39, 260–4.
Bigorne, R. (1989) Les gensres Brienomyrus et Isichthys (Pisces, Mormyridae) en Afrique de l'Ouest. Rev. Hydrobiol. trop. 22 (4), 317–38.
Birdsong, R.S., Murdy, E.O. and Pezold, F.L. (1988) A study of the vertebral column and median fin osteology in gobioid fishes with comments on gobioid relationships. Bull. Mar. Sci. 42, 174–214.
Daget, J. (1954) Les poissons du Niger superieur. Mem. IFAN 36, 1–391.
Daget, J. (1979) Contribution a la fauna de la Republique Unie du Cameroun. Poissons de l'Ayina, du Dja et du Bas Sanaga. Cybium, 3 (6), 55–64.
Daget, J., Gosse, J.P., Teugels, G.G. and Thys van den Audenaerde, D.F.E. (1991) CLOFFA 4. Check-list of the freshwater fishes of Africa. Tervuren-Paris: ISNB-MRAC-ORSTOM.
Daget, J., Gosse, J.P. and Thys van den Audenaerde, D.F.E. (1984) CLOFFA 1. Check-list of the freshwater fishes of Africa. Tervuren-Paris: MRAC-ORSTOM.
Eisentraut, M. (1973) Beitrang zur vogelfauna von Fernando Poo und West Kamerun. Bonner Zoologische Monographien 3, 1–430.
Fa, J.E. (1991) Conservación de los Ecosistemas Forestales en Guinea Ecuatorial. Cambridge and Gland: IUCN.
Harrison, I.J. (1990) A revised synomy of Nematogobius maindroni (Sauvage, 1880) (Teleotei, Gobiidae). Cybium 14, 27–35.
Hugueny, B. (1990) Biogeographie et structure des peuplements de poissons d'eau duouce de l'Afrique de l'Ouest: approches quantitatives. ORSTOM. Travaux et Documents Microédités, 65, 1–300.
Leveque, C., Guegan, J.F. (1990) Les grands Barbus (Pisces, Cyprinidae) d'Afrique de l'Ouest: revision systematique et parasitofaune branchiale. Rev. Hydrobiol. trop., 23, 41–65.
Leveque, C., Paugy, D. and Teugels, G. (1990) Faune des poissons d'eaux douces et saumatres d'Afrique de l'Ouest. Paris-Tervuren: ORSTOM-MRAC.
Leveque, C., Paugy, D. and Teugels, G. (1992). Faune des poissons d'eaux douces et saumatres d'Afrique de l'Ouest. Paris-Tervuren: ORSTOM-MRAC.
McDowell, R.M. (1988) Diadromy in Fishes, Migrations between Freshwater and Marine Environments. London: Croom Helm.
Miller, P.J., Smith, R.McK. (1989) The West African species of the Bathygobius (Teleostei: Gobiidae) and their affinities. J. Zool., Lond. 218, 277–318.
Murdy, E.O. (1989) A taxonomic revision and cladistic analysis of the Oxudercine Gobies (Gobiidae: Oxudercine). Rec. Austr. Mus. 11, 1–93.
Myers, G.S. (1949) Salt tolerance of Freshwater Fish Groups in relation to zoogeographical problems. Bijdr. Dierk 28, 315–22.
Osorio, B. (1898) Da distribuçao geographica dos peixes e crustaceos colhidos nas possessoes Portuguesas d'Africa Occidental e existentes no Museu Nacional de Lisboa. J. Sc. Acad. Sc. Lisboa, (2° ser., TV) XIX, 185–202.
Quero, J.C., Hureau, J.C., Karrer, C., Post, A. and Saldanha, L. (1990) CLOFETA I-II-III. Check-list of the fishes of the eastern tropical Atlantic. JNICT-Portugal: UNESCO, SEI.
Radda, A. and Purzl, E. (1987) Colour Atlas of Cyprinodonts of the Rain Forests of Tropical Africa. Wien: O. Hofmann-Verlag.
Risch, L. and Thys van den Audenaerde, D.F.E. (1979). On the West African species of the genera Sycidium C.V. and Lentipes Gthr. Rev. Zool. afr. 93, 891–900.
Roberts, T.R. (1975) Geographical distribution of African freshwater fishes. Zool. J. Linn. Soc. 57, 249–319.
Róman, B. (1971) Peces de Rio Muni. Guinea Ecuatorial (Aguas dulces y salobres). Barcelona: Roman.
Scheel, J.J. (1968a) A new species of Aphyosemion (Cyprinodontidae, Pisces) from Fernando Poo. Rev. Zool. Bot. afr. 78, 332–42.
Scheel, J.J. (1968b) A review of Aplocheilichthys macrophthalmus Meinken, 1932 (Teleostomi, Cyprinodontidae, Procatopodinae). J. Am. Killifish Ass. 5, 14–23.
Schneider, W. (1990) Field Guide to the Commercial Marine Resources of the Gulf of Guinea. Rome: FAO Species Identification Sheets for Fishery Purposes, Food and Agriculture Organization.
Seret, B. and Opic, P. (1981) Poissons de mer de l'Ouest africain tropical. ORSTOM. Initiations-Documentations tecniques, 49, 1–416.
Teugels, G.G. (1986) A systematic revision of the African species of the genus Clarias (Pisces, Claridae). Annl. Mus. r. Afr. cent. 249, 1–199.
Teugels, G.G., Risch, L., DeVos, L. and Thys van den Audenaerde, D.F.E. (1991) Generic review of the African bagrid genera Auchenoglanis and Parauchenoglanis with description of a new genus. J. nat. Hist. 25, 499–517.
Teugels, G.G., Reid, G.McG. and King, R.P. (1992) Fishes of the Cross river basin (Cameroon-Nigeria). Taxonomy, Zoogeography, Ecology and Conservation. Ann. Mus. r. Afr. cent. 266, 1–132.
Thys van den Audenaerde, D.F.E. (1967) The freshwater fishes of Fernando Poo. Verg. Kon. VI. Akad. Wet. Let. Sch. Kunst. 29, 1–167.
Thys van den Audenaerde, D.F.E. (1968) Addendum to the ‘Freshwater fishes of Fernando Poo’. On some fishes collected by J.J. Scheel. Rev. Zool. Bot. afr. 78, 123–8.
Travers, R.A. (1984a) A review of the Mastacembeloidei, a suborder of synbranchiform teleost fishes. Part I: Anatomical descriptions. Bull. Br. Mus. nat. Hist. (Zool.) 46, 1–133.
Travers, R.A. (1984b) A review of the Mastacebeloidei, a suborder of synbranchiform teleost fishes. Part II: Phylogenetic analysis. Bull. Br. Mus. nat. Hist. (Zool.) 47, 83–150.
Trewavas, E. (1974) The freshwater fishes of Rivers Mungo and Meme and Lakes Kotto, Mboandong and Soden, west Cameroon. Bull. Br. Mus. nat. Hist. (Zool.) 26, 331–419.
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Castelo, R. Biogeographical considerations of fish diversity in Bioko. Biodivers Conserv 3, 808–827 (1994). https://doi.org/10.1007/BF00129660
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DOI: https://doi.org/10.1007/BF00129660