Polycyclic aromatic hydrocarbon (PAHs) and amino acid profile in <i>Oreochromis niloticus</i> along four fishing villages of Sokoto State, Nigeria

This study aims to examine the amino acid profile and concentration of polycyclic aromatic hydrocarbons (PAHs) in fresh and smoked Oreochromis niloticus from four fishing communities (Wurno, River Rima, Romo Lake, and Shagari Reservoir) in Sokoto State, Nigeria. The amino acid profiles and PAHs of the samples were determined using Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Data collected were subjected to analysis of variance. There were significant differences (p<0.05) in both essential and nonessential amino acids of both fresh and Smoked O. niloticus caught from four distinct aquatic environments. Proline (5.483±0.05g/100g protein and 5.024±0.05g/100g protein) recorded the highest mean value in fresh fish caught from Romo and Wurno respectively, likewise leucine composition (5.320±0.05 and 5.19±0.058g/100g protein) from fresh fish of Shagari reservoir and Wurno water body respectively. Wurno smoked fish have the highest levels of Arginine, Lysine, Alanine, Glycine and Aspartic acid which are crucial for growth, protein synthesis, energy metabolism and collagen structure. While all four locations provide a good source of protein, Wurno and River Rima appear to offer a more balanced and higher concentration of essential amino acids. The most abundant PAHs in fresh fish samples is Chrysene (CHRY), consistently showing the highest concentration across all four landing sites, with high mean concentration at the River Rima, Romo, and Shagari sites (>21 μg/kg). Consequently, the results show an enormous increase in PAHs concentrations in smoked fish compared to the fresh O. niloticus samples. For example, Naphthalene concentrations, which were around 2 µg/kg in fresh fish, skyrocketed to a maximum of 48.743 µg/kg in smoked O. niloticus. There were also high levels of Dibenzo [a, h] anthracene (9.434±0.80 µg/kg) and Anthracene (22.946±0.410 µg/kg). The findings strongly suggests that the traditional smoking methods used in these locations are a major source of PAHs contamination and require attention from public health and regulatory bodies.