When sourcing Atlantic Mackerel, buyers must prioritize sensory evaluation and technical specifications. High-quality mackerel should have firm flesh, clear bulging eyes, and bright red gills. From a technical standpoint, ensure the fat content is between 15% and 25% for the best flavor profile, especially if intended for canning or smoking. Verify that the histamine levels are below 50 ppm to ensure food safety and prevent scombroid poisoning. Additionally, check for uniform sizing (e.g., 300-500g or 400-600g) to ensure consistency in processing lines.