<p>Fishers possess valuable experiential knowledge of marine environments, yet local ecological knowledge (LEK) remains underutilized in formal stock assessments. This study compares LEK from 26 fishing ports in Poland and Germany with ICES (International Council for the Exploration of the Sea)-derived relative spawning stock biomass (SSB) and fisheries-independent catch-per-unit-effort (CPUE) data to examine spatial variation in perceived fish stock abundance across the southern Baltic Sea. Structured Likert-scale surveys captured fishers’ assessments of six key commercial stocks—Western and Eastern Baltic cod, Western and Central Baltic herring, sprat, and flounder—across ICES subdivisions (SDs) 24–26. A cumulative link mixed modelling approach was applied to assess the effects of species, region, and fishing activity type on perceived stock abundance while accounting for clustering at the level of fishers and ports. CPUE data derived from the Baltic International Trawl Survey were incorporated as an empirical indicator of stock abundance at comparable spatial scales. Statistical analysis revealed strong alignment between LEK, SSB, and CPUE for severely depleted stocks such as Western and Eastern cod, where fishers consistently reported stock collapse. In contrast, perceptions diverged for herring, sprat, and flounder, reflecting spatial variability in stock availability. Comparison with CPUE indicates that many localized perceptions correspond to survey-based patterns, particularly for sprat concentrations in SD 25 and variable flounder abundance across subdivisions. These results underscore that LEK provides spatially resolved insight into stock dynamics, complementing stock-wide scientific assessments. Integrating LEK with CPUE and ICES indicators can improve the spatial resolution of stock evaluations and support the assessment of data-limited species in the Baltic Sea.</p> Graphical abstract <p></p>