Demographic parameters and exploitation rate of five key fishes of Okpara Stream, Oueme River, Benin, West Africa

Growth parameters Exploitation rate Length at first capture Management Recruitment.

Authors

  • Rachad Sidi Imorou Laboratory of Ecology and Management of Aquatic Ecosystems, Department of Zoology, Faculty of Science and Technology, University of Abomey-Calavi, Cotonou, Benin.
  • Alphonse Adite Laboratory of Ecology and Management of Aquatic Ecosystems, Department of Zoology, Faculty of Science and Technology, University of Abomey-Calavi, Cotonou, Benin.
  • Edmond Sossoukpe Research Laboratory on Wetlands (LRZH), Department of Zoology, Faculty of Science and Technology, University of Abomey-Calavi, Cotonou, Benin.
  • Kayode Nambil Adjibade Laboratory of Ecology and Management of Aquatic Ecosystems, Department of Zoology, Faculty of Science and Technology, University of Abomey-Calavi, Cotonou, Benin.
  • Hamidou Arame Laboratory of Ecology and Management of Aquatic Ecosystems, Department of Zoology, Faculty of Science and Technology, University of Abomey-Calavi, Cotonou, Benin.
  • Stanislas Pejanos Sonon Laboratory of Ecology and Management of Aquatic Ecosystems, Department of Zoology, Faculty of Science and Technology, University of Abomey-Calavi, Cotonou, Benin.
December 25, 2019

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The current study was carried out on Okpara Stream in Northern Benin to evaluate the demographic factors with inferences on fisheries status of five dominant fish species, which were sampled monthly intervals for 18 months. Asymptotic length (L∞) ranged from 36.23 cm (Brycinus macrolepidotus) to 18.8 cm (Hemichromis fasciatus). Growth rates (K) varied between 1.6 yr-1 and 0.66 yr-1 with growth performance index (Φ') ranging from 2.4 to 3.1. Theoretical age at length zero (t0) varied -0.95 year for Marcusenius senegalensis to -0.59 year for Shilbe intermedius. Except for B. macolepidotus, total mortalities were higher than 2 year-1 and length at first capture (L50) ranged 7.72-12.09 cm. Marcusenius senegalensis and S. intermedius showed one annual peak of recruitment, whereas H. fasciatus, Oreochromis niloticus and B. macrolepidotus displayed two peaks. The results indicated that the stocks of these five species were underexploited. However, the low length at first capture (L50) recorded for some species, requires the implementation of early fisheries management scheme to assure a sustainable exploitation of these fishes.