Informality in the maritime food sector spans a spectrum of unregistered vessels, undocumented labor and unregulated processing, all of which undermine food safety, community livelihoods and environmental stewardship. This paper first reviews the distinctive features of informal food production in primary sectors, focusing on small-scale fisheries. We then identify the economic (poverty, limited credit), regulatory (weak enforcement, high compliance costs), and social (limited training, cultural norms) drivers of informality, showing how each factor jeopardizes handling, hygiene, traceability, and hazard exposure. In contexts lacking primary data, we propose a mixed-methods toolkit, comprising Delphi panels, participatory rural appraisal, remote sensing, proxy indicators, and system dynamics modelling, to estimate risk. A focused discussion of marine poaching highlights food-health hazards, from microbial contamination to chemical misuse, exacerbated by supply-chain opacity. We conclude with a human-centered narrative that re-frames policy interventions (e.g., tiered licensing, community monitoring, subsidized training) as collaborative efforts rather than top-down mandates. Finally, we outline future research directions -spanning rapid field diagnostics, gender-sensitive training, digital traceability pilots, and hybrid governance models- aimed at co-creating safe, inclusive, and sustainable maritime food systems.