Empirical Assessment of the Impact of Artisanal Fishing on Macrobenthos Diversity in Creeks of Bayelsa State

Artisanal fishing activities in the creek systems of Bayelsa State, South South Nigeria, involve the widespread use of drag nets and seine nets that physically disturb benthic substrates, yet the cumulative ecological impact of these practices on macrobenthic invertebrate communities has not been empirically quantified. This study empirically assesses the relationship between artisanal fishing intensity and macrobenthic diversity and abundance in eight creek sections in Sagbama and Ekeremor Local Government Areas. Fishing effort at each creek section was quantified over six months through daily observer counts of net deployments. Macrobenthos were sampled using a Van Veen grab sampler at four stations per creek section at the start, midpoint, and end of the monitoring period. Sediment texture, organic carbon content, total petroleum hydrocarbon, and pH were measured concurrently. Results showed that macrobenthic species richness was significantly negatively correlated with fishing effort intensity (r = negative 0.74, p less than 0.01). Polychaete abundance declined markedly in high-effort creek sections, while oligochaetes, which tolerate physical disturbance, increased in relative proportion. Shannon diversity indices were lowest in the highest-effort creek sections. Sediment petroleum hydrocarbon contamination independently contributed to diversity reduction at two creek sections. The study provides empirical evidence that artisanal seine and drag netting significantly impairs macrobenthic communities in Bayelsa State creeks and recommends restrictions on seine net use in ecologically sensitive creek zones, supported by community-based patrol systems.

Keywords: macrobenthos, artisanal fishing, benthic diversity, creek system, Bayelsa State