A study of ecological traits in two Chrysichthys species (Chrysichtys auratus and Chrysichtys nigrodigitatus; Pisces, Siluriformes, Claroteidae) in the Lake Nokoue, Porto-Novo Lagoon complex in South Benin
1995
Laleye, P.A. (Universite Nationale du Benin, Cotonou (Benin). Faculte des Sciences Agronomiques)
The ecology traits have been studied in 2.738 Chrysichthys nigrodigitatus and 990 Chrysichtys auratus caught in 1990-1991 by artisanal fishing in Nokoue Lake and Porto-Novo Lagoon in Benin. The study evidences important differences between the two species. Indeed, the sexual maturity length is much smaller in C. auratus (8-19 cm) than in Chrysichtys nigrodigitatus (23.5-34.5 cm). C. nigrodigitatus grows faster than C. auratus (total length at 5 years of age 40 cm and 30 cm, respectively) and reaches larger size (maximum total lengths expected from von Bertalanffy models 93 cm and 40 cm, respectively). About feeding ecology, C. auratus emerges as generalist feeder (Regularity index Rv = 0.84); on the contrary, size and age related shifts were evidenced in C. nigrodigitatus (Regularity index Rv from 0.82 to 0.59). The eventuality for the two species to belong to two different types of life history and the effect of fishing on the populations are discussed.
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