Gas flaring remains one of the most persistent environmental hazards associated with crude oil exploration and production in the Niger Delta region of Nigeria, with Delta State hosting a dense concentration of flow stations and flare stacks within riverine, fishery-dependent communities. This study examined the effect of gas flaring on aquatic life in Delta State, disaggregating gas flaring into three explanatory dimensions, namely flare intensity, emission of toxic pollutants, and thermal pollution, and their effect on aquatic life, operationalised through fish population abundance, aquatic biodiversity, and fish reproductive success. The study adopted a cross-sectional survey design. The population comprised 1,200 artisanal fisherfolk, fisheries/environmental agency personnel, and community residents across seven flare-impacted local government areas of Delta State. A sample of 300 respondents was drawn using the Taro Yamane formula and a multi-stage sampling technique. A structured, validated twenty-item questionnaire measured on a five-point Likert scale was administered, yielding a 100 per cent response rate. Data were analysed using descriptive statistics, Cronbach’s alpha reliability analysis, Pearson correlation, and multiple linear regression. All constructs returned Cronbach’s alpha coefficients above 0.70. The regression model was statistically significant, R-squared = 0.400, F(3, 296) = 65.881, p < 0.001. Flare intensity (β = 0.245, p < 0.001), emission of toxic pollutants (β = 0.298, p < 0.001), and thermal pollution (β = 0.243, p < 0.001) each exerted a positive and statistically significant effect on aquatic life deterioration, with emission of toxic pollutants emerging as the strongest predictor. The study concludes that gas flaring, through the combined pathways of combustion intensity, toxic pollutant emission, and thermal loading, significantly and adversely affects aquatic life in the oil-producing communities of Delta State, and recommends strengthened enforcement of gas flare-down obligations, improved pollutant monitoring, and thermal discharge management by regulatory agencies and oil-producing companies operating in the state.

Keywords: Gas Flaring; Flare Intensity; Toxic Pollutants; Thermal Pollution; Aquatic Life; Delta State; Niger Delta.