Empirical Analysis of Stock-Recruitment Relationships for Atlantic Bumper (Chloroscombrus chrysurus) in the Gulf of Guinea

Understanding stock-recruitment dynamics is fundamental to sustainable fisheries management, yet robust empirical data for small pelagic species in the Gulf of Guinea remain critically limited. This study developed and evaluated stock-recruitment models for Atlantic bumper (Chloroscombrus chrysurus) using time series catch and effort data from the Nigerian industrial trawl survey database spanning 2015 to 2024. Age-structured stock assessment was conducted using the FiSAT II software package incorporating catch curve analysis, virtual population analysis, and length-based cohort analysis. Beverton-Holt and Ricker stock-recruitment models were fitted using maximum likelihood estimation, and model selection was conducted using Akaike Information Criterion. Standardised indices of abundance were derived through generalised linear model analysis of trawl survey data. The best-fit model was Beverton-Holt with steepness parameter h = 0.74, indicating moderate resilience. Estimates of fishing mortality (F = 0.81 per year) exceeded the reference point of Fmsy (0.52 per year) by 56 percent, confirming significant overfishing. Recruitment showed significant interannual variability explained by sea surface temperature anomalies (r squared = 0.61) and North Atlantic Oscillation indices. The spawning stock biomass per recruit analysis indicated that current exploitation has reduced the spawning stock to approximately 28 percent of its unfished level. The study provides the first empirically calibrated stock-recruitment framework for C. chrysurus in Nigerian waters and recommends immediate reductions in directed fishing effort to achieve recovery. Keywords: stock-recruitment, Chloroscombrus chrysurus, Gulf of Guinea, virtual population analysis, overfishing.