Abstract
This study provides the first national, species disaggregated quantitative assessment of structural changes in Portuguese marine fisheries over three decades (1995 – 2024), coinciding with major reforms of the European Union’s Common Fisheries Policy (CFP). Using annual landings data for 47 species, Spearman rank correlation was applied to detect long term monotonic trends between year and landing volume, a non parametric approach robust to non normality, zeros, and outliers. Results reveal a pervasive decline: 26 species (55.3%) exhibited significant negative trends (ρ as low as −0.953, P < 0.001), including commercially important demersals such as European hake and gurnards. Conversely, 9 species (19.1%) showed significant positive trends (e.g. Atlantic mackerel, European sea bass; ρ up to +0.778, P < 0.001), while 12 species (25.5%) remained statistically non significant. These patterns are directionally consistent with CFP objectives to reduce fishing mortality and promote selective exploitation, while acknowledging alternative drivers such as climate variability and reporting changes. The findings indicate systemic restructuring of Portuguese fisheries, with widespread reductions in demersal landings and selective increases among pelagic species, reflecting adaptive responses to regulatory and ecological pressures. This work contributes novel species level evidence of long term structural transformation, offering a baseline for future causal analyses using interrupted time series or multivariate approaches. By quantifying monotonic trends across 47 species, the study enhances understanding of policy aligned shifts in fleet behavior and ecosystem exploitation, informing adaptive governance and sustainability strategies under evolving EU fisheries frameworks.