Abundance, Species Diversity, Length-Weight Relationship and Conditon Factor of Family Mormyridae in Lower River Niger, Lokoja, Kogi State

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@article{1714369,
      author = {Omede H, Onimisi M. M., Kehinde, F. O., Onoja, A. E.},
      title = {Abundance, Species Diversity, Length-Weight Relationship and Conditon Factor of Family Mormyridae in Lower River Niger, Lokoja, Kogi State},
      journal = {Iconic Research And Engineering Journals},
      year = {2026},
      volume = {9},
      number = {8},
      pages = {2676-2688},
      issn = {2456-8880},
      url = {https://www.irejournals.com/formatedpaper/1714369.pdf},
      abstract = {This study investigated the species composition, diversity, and length-weight relationships of Family Mormyridae assemblages in the lower River Niger at Lokoja, Kogi State, Nigeria, to provide insight into their ecological status and population structure. A total of 208 individuals representing 11 species and six genera were collected between June and December 2024 and were identified. Mormyrus rume (19.7%) and Hippopotamyrus psittacus (13.9%) were the most abundant species, reflecting their adaptive success in the habitat. Diversity indices revealed moderate to high heterogeneity (Simpson’s index = 0.90; Shannon–Wiener index H′ = 2.3; Margalef’s richness = 1.8; Evenness = 0.9), indicating a relatively balanced fish community. The length–weight relationship exhibited interspecific variation, with regression coefficients (b) ranging from 1.29 to 3.36. Most species displayed negative allometric growth (b < 3), suggesting that increase in weight was disproportionate to length increment, possibly due to environmental stress or food limitation. The condition factor (K) ranged between 0.72 and 1.44, implying variable well-being among species. Length and weight frequency distributions were skewed toward smaller size classes, which may reflect recruitment dominance or selective fishing pressure. These findings demonstrate that the Family Mormyridae assemblage in the lower River Niger is under moderate ecological stability but exhibits signs of anthropogenic stress. Continuous monitoring, enforcement of size-limit regulations, and habitat conservation are recommended to sustain population balance and biodiversity integrity within the system.},
      keywords = {abundance; diversity index; length–weight relationship; condition factor; Mormyridae},
      month = {February},
      doi = {https://doi.org/10.64388/IREV9I8-1714369}
  }