Ecological observations on juvenile flatfish in a tropical estuary: Arquipélago dos bijagós, Guinea-Bissau

Abstract

Juvenile flatfish were studied in a tropical estuary, Arquipélago dos Bijagós in Guinea-Bissau from October 1992 until April 1993. A total of eight flatfish species, belonging to the families Bothidae, Cynoglossidae, Psettodidae and Soleidae, were found. In comparison with other fish groups, flatfishes abundance was low with densities of less than 13 ind·100 m⁻². One species, Citharichthys stampflii, occurred in densities high enough to permit an analysis of distribution, growth and mortality. During the period of study, settlement of C. stampflii was observed in the estuary. Its distribution suggested a preference for offshore areas, densities decreasing towards the river systems. Repeated sampling in the intertidal area of Ilheu de Flamingos permitted a preliminary estimate of mortality and growth. Instantaneous mortality rates were about 0.03·d⁻¹, which is similar to estimates in temperate estuaries. Growth rates were slightly above 1 mm·d⁻¹, about the same as those measured in subtropical estuaries.